https://orcid.org/0000-0002-3045-9475
Abstract
The incidence of postoperative complications is relatively high in smokers. Although 4-week smoking cessation before surgery is generally recommended, it has not been sufficiently studied in lung cancer surgery. This study investigated whether smoking cessation for a short period of time significantly reduced complications after lung cancer surgery.
This was a retrospective, observational study that investigated the relationship between the smoking cessation period and the incidence of complications in lung cancer surgery. Patients who underwent curative-intent surgery for lung cancer at our institution between January 2014 and December 2017 were included. The smokers were classified into the following 4 categories of smoking cessation period before surgery: current (<4 weeks), recent (4 weeks to 12 months), distant (12 months to 5 years) and ex-smokers (>5 years).
A total of 911 patients were included in this study. The incidence of pulmonary complications was 5 times higher in the smoker group than in the never smoker group (12.9% vs 2.5%, P < 0.001). On multivariable analysis in both models, the odds ratio for complications was significantly higher in distant smokers than in recent smokers and never smokers. Across all models, low lung function significantly predicted the development of postoperative complications.
The evidence-based smoking cessation duration that reduces the incidence of complications after thoracic surgery remains unclear. The incidence of postoperative complications was more strongly affected by low pulmonary function than by the duration of preoperative smoking cessation. For patients with marginal indications for surgery, postponing surgery to accommodate a smoking cessation period seemed unnecessary.
INTRODUCTION
Smoking is the leading cause of lung cancer and low pulmonary function [1, 2]. The standard treatment for resectable lung cancer is surgery, but postoperative complications occur in ∼20% of cases [3]. Smoking is associated with postoperative complications and can affect the rate of survival after surgery [4, 5]. Previous meta-analyses reported that smoking cessation for 2–4 weeks before various types of surgery was effective in reducing postoperative complications, and the World Health Organization recommends stopping smoking at least 4 weeks before surgery [6]. The effect of short smoking cessation on thoracic surgery should be specifically examined, but only few thoracic surgery studies had been included in these meta-analyses [7, 8]. Although 1 single-centre retrospective study [9] has reported that smoking cessation for about 2 months before thoracic surgery had an effect on postoperative complications, a prospective trial and a large database study have failed to reveal the most effective preoperative smoking cessation period [10, 11].
For lung cancer, which is a progressive disease, surgery should be ideally performed as early as possible. However, the most effective duration of smoking cessation to reduce postoperative complications had been controversial. In this study, we classified the duration of preoperative smoking cessation into 4 categories and examined the association between the duration of preoperative smoking cessation and postoperative complications.
PATIENTS AND METHODS
Ethical statement
This was a retrospective study on all patients who underwent curative-intent surgery for lung cancer between January 2014 and December 2017 at a single hospital. The study protocol was approved by the institutional review board of Nagoya University School of Medicine (2018-0258, 11 January 2018), and the requirement for informed consent was waived because of the retrospective design of the study.
The records of all the eligible patients were reviewed using our prospectively collected database, which was filled in by the medical clerk and confirmed by the attending physician. Data on patient characteristics, patient self-reported smoking history, comorbidities, Charlson comorbidity index (CCI) [12], preoperative respiratory function, type of surgery, clinical and pathologic stage, length of hospital stay and postoperative complications were collected. This study complied with the STROBE guidelines [13].
Variable definition
The patients were categorized as follows according to the preoperative smoking status: current (<4 weeks), recent (4 weeks to 12 months), distant (12 months to 5 years), ex-smokers (>5 years) and never smokers. The clinical and pathological staging was confirmed based on the tumour–node–metastasis classification, 7th edition [14]. Comorbidities and complications within 30 days of surgery were recorded under the previously reported National Clinical Database criteria [15]. Major complications were defined as follows: air leak that lasted >7 days or required treatment, including chemical pleurodesis and repeat drainage; pneumonia with elevated inflammation, as confirmed on radiologic imaging; and arrhythmias requiring treatment.
Statistical methods
Descriptive results were presented as counts and percentages for categorical variables. Continuous data were summarized as mean and standard deviation; those with skewed distributions were presented as median and interquartile range. Pearson’s chi-square or Fisher’s exact test was performed for categorical variables, and the Mann–Whitney U-test, Kruskal–Wallis test, Student’s t-test or analysis of variance for continuous variables was performed after the assessment of normality of data. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the development of postoperative complications based on smoking status. Trend analyses of the OR were performed by contrasts of regression coefficients from each logistic regression. In model 1, we assessed the impact of both the smoking cessation period and pack-years in the smokers-only cohort and adjusted for possible confounders, such as age, sex, CCI, respiratory function and clinical stage, as described in previous studies [5, 10]. In models 2 and 3, we examined the impact of smoking cessation period and pack-years, respectively, on the development of postoperative complications in the entire cohort using the same confounders in model 1. Missing data were not imputed, and listwise deletion was applied because of few missing data. Because this study was an exploratory observational study, no adjustment for multiplicity was made. Statistical analyses were performed using Stata (version 15.1; Stata Corporation, College Station, TX, USA) and SPSS version 27.0 (IBM, Chicago, IL, USA). All P-values were two-sided, and P-values <0.05 were considered significant.
RESULTS
In the overall cohort of 911 cases, 276 (30.2%) were never smokers and 88 (9.6%) were current smokers. The patient characteristics in terms of preoperative smoking cessation periods are summarized in Table 1. Compared with never smokers, the smoker groups had more men, higher CCI, more comorbidities and more advanced stages. Lung function was lowest in the current smoker group, whereas most comorbidities tended to be most frequent in the distant smoker and ex-smoker groups. The type and approach of surgery did not differ significantly among the groups.
Baseline characteristics and results stratified by smoking status
| Variable | Current smokers, | Recent smokers, | Distant smokers, | Ex-smokers, | Never smokers, | P-Value |
|---|---|---|---|---|---|---|
| (n = 88) | (n = 156) | (n = 122) | (n = 269) | (n = 276) | ||
| Age, mean ± SD | 66.3 ± 8.9 | 65.0 ± 9.4 | 69.2 ± 6.2 | 71.1 ± 7.8 | 67.5 ± 10.2 | <0.001a |
| Gender, men, % (n) | 87.5% | 85.3% | 87.7% | 84.0% | 18.1% | <0.001b |
| (n = 77) | (n = 133) | (n = 107) | (n = 226) | (n = 50) | ||
| BMI, mean ± SD | 22.2 ± 3.3 | 22.3 ± 3.5 | 22.2 ± 3.3 | 22.9 ± 3.2 | 22.3 ± 3.5 | 0.162a |
| Pack-years, median (IQR) | 54 (41, 72) | 50 (37, 63) | 55 (46, 89) | 41 (23, 64) | 0 | <0.001c |
| Charlson comorbidity index, ≧1, % (n) | 59.1 (52) | 54.5 (85) | 67.2 (82) | 58.0 (156) | 38.4 (106) | <0.001b |
| Medical history, % (n) | ||||||
| Interstitial pneumonia | 4.5 (4) | 6.4 (10) | 10.7 (13) | 4.8 (13) | 1.4 (4) | 0.001d |
| Ischaemic heart disease | 3.4 (3) | 5.8 (9) | 10.7 (13) | 14.1 (38) | 1.4 (4) | 0.001d |
| Malignant disease | 21.6 (19) | 12.2 (19) | 27.0 (33) | 14.5 (39) | 18.5 (51) | 0.009b |
| Cerebrovascular disease | 9.1 (8) | 4.5 (7) | 9.0 (11) | 10.0 (27) | 9.1 (18) | 0.254b |
| Diabetes mellitus | 25.0 (22) | 21.2 (33) | 25.4 (31) | 25.7 (69) | 15.2 (42) | 0.028b |
| Hypertension | 33.0 (29) | 24.4 (38) | 26.2 (32) | 26.0 (70) | 17.0 (47) | 0.016b |
| Dialysis | 0.0 (0) | 1.3 (2) | 0.8 (1) | 2.6 (7) | 0.0 (0) | 0.037d |
| Respiratory function | ||||||
| %VC, mean ± SD | 99.1 ± 12.6 | 101.7 ± 13.4 | 97.5 ± 16.3 | 102.5 ± 15.7 | 105.2 ± 16.6 | <0.001a |
| %FEV1.0, mean ± SD | 69.1 ± 9.2 | 69.3 ± 14.9 | 70.7 ± 10.6 | 70.5 ± 11.1 | 75.3 ± 8.9 | <0.001a |
| Type of surgery, % (n) | 0.517b | |||||
| Wedge | 1.1 (1) | 3.8 (6) | 5.7 (7) | 4.5 (12) | 4.3 (12) | |
| Segmentectomy | 4.5 (4) | 10.3 (16) | 10.7 (13) | 8.9 (24) | 12.3 (34) | |
| Lobectomy | 92.0 (81) | 82.7 (129) | 81.1 (99) | 85.1 (229) | 82.2 (227) | |
| Pneumonectomy | 2.3 (2) | 3.2 (5) | 2.5 (3) | 1.5 (4) | 1.1 (3) | |
| Approach, VATS/RATS, % (n) | 44.9 (40) | 39.9 (63) | 41.5 (51) | 45.6 (124) | 57.4 (159) | 0.002b |
| Clinical stage, % (n) | ||||||
| l | 63.6 (56) | 60.3 (94) | 69.7 (85) | 71.0 (191) | 86.2 (238) | <0.001b |
| ll | 22.7 (20) | 23.7 (37) | 17.2 (21) | 20.4 (55) | 10.9 (30) | |
| lll | 13.6 (12) | 16.0 (25) | 13.1 (16) | 8.6 (23) | 2.9 (8) | |
| Histologic type, % (n) | ||||||
| Adenocarcinoma | 53.9 (48) | 50.0 (79) | 48.0 (59) | 60.3 (164) | 86.6 (240) | <0.001b |
| Squamous cell carcinoma | 28.1 (25) | 32.9 (52) | 35.0 (43) | 27.9 (76) | 1.8 (5) | |
| Variable | Current smokers, | Recent smokers, | Distant smokers, | Ex-smokers, | Never smokers, | P-Value |
|---|---|---|---|---|---|---|
| (n = 88) | (n = 156) | (n = 122) | (n = 269) | (n = 276) | ||
| Age, mean ± SD | 66.3 ± 8.9 | 65.0 ± 9.4 | 69.2 ± 6.2 | 71.1 ± 7.8 | 67.5 ± 10.2 | <0.001a |
| Gender, men, % (n) | 87.5% | 85.3% | 87.7% | 84.0% | 18.1% | <0.001b |
| (n = 77) | (n = 133) | (n = 107) | (n = 226) | (n = 50) | ||
| BMI, mean ± SD | 22.2 ± 3.3 | 22.3 ± 3.5 | 22.2 ± 3.3 | 22.9 ± 3.2 | 22.3 ± 3.5 | 0.162a |
| Pack-years, median (IQR) | 54 (41, 72) | 50 (37, 63) | 55 (46, 89) | 41 (23, 64) | 0 | <0.001c |
| Charlson comorbidity index, ≧1, % (n) | 59.1 (52) | 54.5 (85) | 67.2 (82) | 58.0 (156) | 38.4 (106) | <0.001b |
| Medical history, % (n) | ||||||
| Interstitial pneumonia | 4.5 (4) | 6.4 (10) | 10.7 (13) | 4.8 (13) | 1.4 (4) | 0.001d |
| Ischaemic heart disease | 3.4 (3) | 5.8 (9) | 10.7 (13) | 14.1 (38) | 1.4 (4) | 0.001d |
| Malignant disease | 21.6 (19) | 12.2 (19) | 27.0 (33) | 14.5 (39) | 18.5 (51) | 0.009b |
| Cerebrovascular disease | 9.1 (8) | 4.5 (7) | 9.0 (11) | 10.0 (27) | 9.1 (18) | 0.254b |
| Diabetes mellitus | 25.0 (22) | 21.2 (33) | 25.4 (31) | 25.7 (69) | 15.2 (42) | 0.028b |
| Hypertension | 33.0 (29) | 24.4 (38) | 26.2 (32) | 26.0 (70) | 17.0 (47) | 0.016b |
| Dialysis | 0.0 (0) | 1.3 (2) | 0.8 (1) | 2.6 (7) | 0.0 (0) | 0.037d |
| Respiratory function | ||||||
| %VC, mean ± SD | 99.1 ± 12.6 | 101.7 ± 13.4 | 97.5 ± 16.3 | 102.5 ± 15.7 | 105.2 ± 16.6 | <0.001a |
| %FEV1.0, mean ± SD | 69.1 ± 9.2 | 69.3 ± 14.9 | 70.7 ± 10.6 | 70.5 ± 11.1 | 75.3 ± 8.9 | <0.001a |
| Type of surgery, % (n) | 0.517b | |||||
| Wedge | 1.1 (1) | 3.8 (6) | 5.7 (7) | 4.5 (12) | 4.3 (12) | |
| Segmentectomy | 4.5 (4) | 10.3 (16) | 10.7 (13) | 8.9 (24) | 12.3 (34) | |
| Lobectomy | 92.0 (81) | 82.7 (129) | 81.1 (99) | 85.1 (229) | 82.2 (227) | |
| Pneumonectomy | 2.3 (2) | 3.2 (5) | 2.5 (3) | 1.5 (4) | 1.1 (3) | |
| Approach, VATS/RATS, % (n) | 44.9 (40) | 39.9 (63) | 41.5 (51) | 45.6 (124) | 57.4 (159) | 0.002b |
| Clinical stage, % (n) | ||||||
| l | 63.6 (56) | 60.3 (94) | 69.7 (85) | 71.0 (191) | 86.2 (238) | <0.001b |
| ll | 22.7 (20) | 23.7 (37) | 17.2 (21) | 20.4 (55) | 10.9 (30) | |
| lll | 13.6 (12) | 16.0 (25) | 13.1 (16) | 8.6 (23) | 2.9 (8) | |
| Histologic type, % (n) | ||||||
| Adenocarcinoma | 53.9 (48) | 50.0 (79) | 48.0 (59) | 60.3 (164) | 86.6 (240) | <0.001b |
| Squamous cell carcinoma | 28.1 (25) | 32.9 (52) | 35.0 (43) | 27.9 (76) | 1.8 (5) | |
Current smokers, <4 weeks; recent smokers, 4 weeks to 12 months; distant smokers, 12 months to 5 years; ex-smokers, >5 years.
ANOVA.
Chi-square test.
Kruskal–Wallis test.
Fisher’s exact test.
%FEV1.0: % forced expiratory volume in 1 s; BMI: body mass index; IQR: interquartile range; RATS: robot-assisted thoracic surgery; SD: standard deviation; VATS: Video-assisted thoracoscopic surgery; %VC: % vital capacity.
Baseline characteristics and results stratified by smoking status
| Variable | Current smokers, | Recent smokers, | Distant smokers, | Ex-smokers, | Never smokers, | P-Value |
|---|---|---|---|---|---|---|
| (n = 88) | (n = 156) | (n = 122) | (n = 269) | (n = 276) | ||
| Age, mean ± SD | 66.3 ± 8.9 | 65.0 ± 9.4 | 69.2 ± 6.2 | 71.1 ± 7.8 | 67.5 ± 10.2 | <0.001a |
| Gender, men, % (n) | 87.5% | 85.3% | 87.7% | 84.0% | 18.1% | <0.001b |
| (n = 77) | (n = 133) | (n = 107) | (n = 226) | (n = 50) | ||
| BMI, mean ± SD | 22.2 ± 3.3 | 22.3 ± 3.5 | 22.2 ± 3.3 | 22.9 ± 3.2 | 22.3 ± 3.5 | 0.162a |
| Pack-years, median (IQR) | 54 (41, 72) | 50 (37, 63) | 55 (46, 89) | 41 (23, 64) | 0 | <0.001c |
| Charlson comorbidity index, ≧1, % (n) | 59.1 (52) | 54.5 (85) | 67.2 (82) | 58.0 (156) | 38.4 (106) | <0.001b |
| Medical history, % (n) | ||||||
| Interstitial pneumonia | 4.5 (4) | 6.4 (10) | 10.7 (13) | 4.8 (13) | 1.4 (4) | 0.001d |
| Ischaemic heart disease | 3.4 (3) | 5.8 (9) | 10.7 (13) | 14.1 (38) | 1.4 (4) | 0.001d |
| Malignant disease | 21.6 (19) | 12.2 (19) | 27.0 (33) | 14.5 (39) | 18.5 (51) | 0.009b |
| Cerebrovascular disease | 9.1 (8) | 4.5 (7) | 9.0 (11) | 10.0 (27) | 9.1 (18) | 0.254b |
| Diabetes mellitus | 25.0 (22) | 21.2 (33) | 25.4 (31) | 25.7 (69) | 15.2 (42) | 0.028b |
| Hypertension | 33.0 (29) | 24.4 (38) | 26.2 (32) | 26.0 (70) | 17.0 (47) | 0.016b |
| Dialysis | 0.0 (0) | 1.3 (2) | 0.8 (1) | 2.6 (7) | 0.0 (0) | 0.037d |
| Respiratory function | ||||||
| %VC, mean ± SD | 99.1 ± 12.6 | 101.7 ± 13.4 | 97.5 ± 16.3 | 102.5 ± 15.7 | 105.2 ± 16.6 | <0.001a |
| %FEV1.0, mean ± SD | 69.1 ± 9.2 | 69.3 ± 14.9 | 70.7 ± 10.6 | 70.5 ± 11.1 | 75.3 ± 8.9 | <0.001a |
| Type of surgery, % (n) | 0.517b | |||||
| Wedge | 1.1 (1) | 3.8 (6) | 5.7 (7) | 4.5 (12) | 4.3 (12) | |
| Segmentectomy | 4.5 (4) | 10.3 (16) | 10.7 (13) | 8.9 (24) | 12.3 (34) | |
| Lobectomy | 92.0 (81) | 82.7 (129) | 81.1 (99) | 85.1 (229) | 82.2 (227) | |
| Pneumonectomy | 2.3 (2) | 3.2 (5) | 2.5 (3) | 1.5 (4) | 1.1 (3) | |
| Approach, VATS/RATS, % (n) | 44.9 (40) | 39.9 (63) | 41.5 (51) | 45.6 (124) | 57.4 (159) | 0.002b |
| Clinical stage, % (n) | ||||||
| l | 63.6 (56) | 60.3 (94) | 69.7 (85) | 71.0 (191) | 86.2 (238) | <0.001b |
| ll | 22.7 (20) | 23.7 (37) | 17.2 (21) | 20.4 (55) | 10.9 (30) | |
| lll | 13.6 (12) | 16.0 (25) | 13.1 (16) | 8.6 (23) | 2.9 (8) | |
| Histologic type, % (n) | ||||||
| Adenocarcinoma | 53.9 (48) | 50.0 (79) | 48.0 (59) | 60.3 (164) | 86.6 (240) | <0.001b |
| Squamous cell carcinoma | 28.1 (25) | 32.9 (52) | 35.0 (43) | 27.9 (76) | 1.8 (5) | |
| Variable | Current smokers, | Recent smokers, | Distant smokers, | Ex-smokers, | Never smokers, | P-Value |
|---|---|---|---|---|---|---|
| (n = 88) | (n = 156) | (n = 122) | (n = 269) | (n = 276) | ||
| Age, mean ± SD | 66.3 ± 8.9 | 65.0 ± 9.4 | 69.2 ± 6.2 | 71.1 ± 7.8 | 67.5 ± 10.2 | <0.001a |
| Gender, men, % (n) | 87.5% | 85.3% | 87.7% | 84.0% | 18.1% | <0.001b |
| (n = 77) | (n = 133) | (n = 107) | (n = 226) | (n = 50) | ||
| BMI, mean ± SD | 22.2 ± 3.3 | 22.3 ± 3.5 | 22.2 ± 3.3 | 22.9 ± 3.2 | 22.3 ± 3.5 | 0.162a |
| Pack-years, median (IQR) | 54 (41, 72) | 50 (37, 63) | 55 (46, 89) | 41 (23, 64) | 0 | <0.001c |
| Charlson comorbidity index, ≧1, % (n) | 59.1 (52) | 54.5 (85) | 67.2 (82) | 58.0 (156) | 38.4 (106) | <0.001b |
| Medical history, % (n) | ||||||
| Interstitial pneumonia | 4.5 (4) | 6.4 (10) | 10.7 (13) | 4.8 (13) | 1.4 (4) | 0.001d |
| Ischaemic heart disease | 3.4 (3) | 5.8 (9) | 10.7 (13) | 14.1 (38) | 1.4 (4) | 0.001d |
| Malignant disease | 21.6 (19) | 12.2 (19) | 27.0 (33) | 14.5 (39) | 18.5 (51) | 0.009b |
| Cerebrovascular disease | 9.1 (8) | 4.5 (7) | 9.0 (11) | 10.0 (27) | 9.1 (18) | 0.254b |
| Diabetes mellitus | 25.0 (22) | 21.2 (33) | 25.4 (31) | 25.7 (69) | 15.2 (42) | 0.028b |
| Hypertension | 33.0 (29) | 24.4 (38) | 26.2 (32) | 26.0 (70) | 17.0 (47) | 0.016b |
| Dialysis | 0.0 (0) | 1.3 (2) | 0.8 (1) | 2.6 (7) | 0.0 (0) | 0.037d |
| Respiratory function | ||||||
| %VC, mean ± SD | 99.1 ± 12.6 | 101.7 ± 13.4 | 97.5 ± 16.3 | 102.5 ± 15.7 | 105.2 ± 16.6 | <0.001a |
| %FEV1.0, mean ± SD | 69.1 ± 9.2 | 69.3 ± 14.9 | 70.7 ± 10.6 | 70.5 ± 11.1 | 75.3 ± 8.9 | <0.001a |
| Type of surgery, % (n) | 0.517b | |||||
| Wedge | 1.1 (1) | 3.8 (6) | 5.7 (7) | 4.5 (12) | 4.3 (12) | |
| Segmentectomy | 4.5 (4) | 10.3 (16) | 10.7 (13) | 8.9 (24) | 12.3 (34) | |
| Lobectomy | 92.0 (81) | 82.7 (129) | 81.1 (99) | 85.1 (229) | 82.2 (227) | |
| Pneumonectomy | 2.3 (2) | 3.2 (5) | 2.5 (3) | 1.5 (4) | 1.1 (3) | |
| Approach, VATS/RATS, % (n) | 44.9 (40) | 39.9 (63) | 41.5 (51) | 45.6 (124) | 57.4 (159) | 0.002b |
| Clinical stage, % (n) | ||||||
| l | 63.6 (56) | 60.3 (94) | 69.7 (85) | 71.0 (191) | 86.2 (238) | <0.001b |
| ll | 22.7 (20) | 23.7 (37) | 17.2 (21) | 20.4 (55) | 10.9 (30) | |
| lll | 13.6 (12) | 16.0 (25) | 13.1 (16) | 8.6 (23) | 2.9 (8) | |
| Histologic type, % (n) | ||||||
| Adenocarcinoma | 53.9 (48) | 50.0 (79) | 48.0 (59) | 60.3 (164) | 86.6 (240) | <0.001b |
| Squamous cell carcinoma | 28.1 (25) | 32.9 (52) | 35.0 (43) | 27.9 (76) | 1.8 (5) | |
Current smokers, <4 weeks; recent smokers, 4 weeks to 12 months; distant smokers, 12 months to 5 years; ex-smokers, >5 years.
ANOVA.
Chi-square test.
Kruskal–Wallis test.
Fisher’s exact test.
%FEV1.0: % forced expiratory volume in 1 s; BMI: body mass index; IQR: interquartile range; RATS: robot-assisted thoracic surgery; SD: standard deviation; VATS: Video-assisted thoracoscopic surgery; %VC: % vital capacity.
The postoperative complications are described in Table 2. Complications within 1 month of surgery occurred in 181 patients (19.8%) and were almost twice as many in the smoker group (23.6%) than in the never smoker group (11.2%). The incidence of pulmonary-related complications was 5 times higher in the smoker group than in the never smoker group (12.9% vs 2.5%, P < 0.001). The results of the univariate analysis of the risk factors for postoperative complications are described in Table 3. Although the ORs in the smoking cessation groups compared to the never smoker group were significantly higher than 1, the trend analysis of the incidence showed a significant trend but not a linear one (P for linear and deviation from linearity; 0.0104 and 0.0003, respectively). ORs in groups of pack-years of 20–60 and >60 compared to the never smoker group were significantly higher than 1 (P for linear trend <0.001). Multivariable analysis revealed a tendency for a higher OR in the current smoker group than in the recent smoker group (OR = 1.32, 95% CI: 0.68–2.56, P = 0.409) (Table 4, model 1). In model 2, the odds for postoperative complications remained significantly higher in the distant smoker group than in the never smoker group (OR = 2.12, 95% CI: 1.11–4.04, P = 0.023). On the other hand, model 3 showed no statistically significant ORs in pack-years in the incidence of postoperative complications. Across all the models, low lung function was a significant predictor of the development of postoperative complications.
Postoperative complication rate within 30 days and surgery-related characteristics
| Variable | Smokers | Never smokers | P-Value |
|---|---|---|---|
| (n = 635) | (n = 276) | ||
| Length of stay (days), mean ± SD | 11.6 ± 11.0 | 8.5 ± 5.0 | <0.001a |
| Operation time (min), mean ± SD | 171.1 ± 88.9 | 138.9 ± 48.6 | <0.001a |
| Blood loss (g), median (IQR) | 65 (21, 153) | 29 (2, 65) | <0.001b |
| Total complications, % (n) | 23.6 (150) | 11.2 (31) | <0.001c |
| Pulmonary complications, % (n) | 12.9 (82) | 2.5 (7) | <0.001c |
| Prolonged air leak | 6.1 (39) | 1.8 (5) | 0.006c |
| Pneumonia | 3.9 (25) | 0.0 (0) | 0.001c |
| Empyema | 2.7 (17) | 0.4 (1) | 0.034c |
| Bronchial fistula | 1.4 (9) | 0.0 (0) | 0.064d |
| Acute interstitial pneumonia | 0.9 (6) | 0.0 (0) | 0.186d |
| Atelectasis | 0.5 (3) | 0.4 (1) | 1.000d |
| Miscellaneous, % (n) | |||
| Arrhythmia | 3.3 (21) | 1.8 (5) | 0.280c |
| Brain infarction | 1.1 (7) | 0.0 (0) | 0.109d |
| Wound infection | 0.3 (2) | 0.4 (1) | 1.000d |
| Reoperation | 3.0 (19) | 3.3 (9) | 0.836c |
| Variable | Smokers | Never smokers | P-Value |
|---|---|---|---|
| (n = 635) | (n = 276) | ||
| Length of stay (days), mean ± SD | 11.6 ± 11.0 | 8.5 ± 5.0 | <0.001a |
| Operation time (min), mean ± SD | 171.1 ± 88.9 | 138.9 ± 48.6 | <0.001a |
| Blood loss (g), median (IQR) | 65 (21, 153) | 29 (2, 65) | <0.001b |
| Total complications, % (n) | 23.6 (150) | 11.2 (31) | <0.001c |
| Pulmonary complications, % (n) | 12.9 (82) | 2.5 (7) | <0.001c |
| Prolonged air leak | 6.1 (39) | 1.8 (5) | 0.006c |
| Pneumonia | 3.9 (25) | 0.0 (0) | 0.001c |
| Empyema | 2.7 (17) | 0.4 (1) | 0.034c |
| Bronchial fistula | 1.4 (9) | 0.0 (0) | 0.064d |
| Acute interstitial pneumonia | 0.9 (6) | 0.0 (0) | 0.186d |
| Atelectasis | 0.5 (3) | 0.4 (1) | 1.000d |
| Miscellaneous, % (n) | |||
| Arrhythmia | 3.3 (21) | 1.8 (5) | 0.280c |
| Brain infarction | 1.1 (7) | 0.0 (0) | 0.109d |
| Wound infection | 0.3 (2) | 0.4 (1) | 1.000d |
| Reoperation | 3.0 (19) | 3.3 (9) | 0.836c |
Student’s t-test.
Mann–Whitney.
Chi-squared test.
Fisher’s exact test.
IQR: interquartile range; SD: standard deviation.
Postoperative complication rate within 30 days and surgery-related characteristics
| Variable | Smokers | Never smokers | P-Value |
|---|---|---|---|
| (n = 635) | (n = 276) | ||
| Length of stay (days), mean ± SD | 11.6 ± 11.0 | 8.5 ± 5.0 | <0.001a |
| Operation time (min), mean ± SD | 171.1 ± 88.9 | 138.9 ± 48.6 | <0.001a |
| Blood loss (g), median (IQR) | 65 (21, 153) | 29 (2, 65) | <0.001b |
| Total complications, % (n) | 23.6 (150) | 11.2 (31) | <0.001c |
| Pulmonary complications, % (n) | 12.9 (82) | 2.5 (7) | <0.001c |
| Prolonged air leak | 6.1 (39) | 1.8 (5) | 0.006c |
| Pneumonia | 3.9 (25) | 0.0 (0) | 0.001c |
| Empyema | 2.7 (17) | 0.4 (1) | 0.034c |
| Bronchial fistula | 1.4 (9) | 0.0 (0) | 0.064d |
| Acute interstitial pneumonia | 0.9 (6) | 0.0 (0) | 0.186d |
| Atelectasis | 0.5 (3) | 0.4 (1) | 1.000d |
| Miscellaneous, % (n) | |||
| Arrhythmia | 3.3 (21) | 1.8 (5) | 0.280c |
| Brain infarction | 1.1 (7) | 0.0 (0) | 0.109d |
| Wound infection | 0.3 (2) | 0.4 (1) | 1.000d |
| Reoperation | 3.0 (19) | 3.3 (9) | 0.836c |
| Variable | Smokers | Never smokers | P-Value |
|---|---|---|---|
| (n = 635) | (n = 276) | ||
| Length of stay (days), mean ± SD | 11.6 ± 11.0 | 8.5 ± 5.0 | <0.001a |
| Operation time (min), mean ± SD | 171.1 ± 88.9 | 138.9 ± 48.6 | <0.001a |
| Blood loss (g), median (IQR) | 65 (21, 153) | 29 (2, 65) | <0.001b |
| Total complications, % (n) | 23.6 (150) | 11.2 (31) | <0.001c |
| Pulmonary complications, % (n) | 12.9 (82) | 2.5 (7) | <0.001c |
| Prolonged air leak | 6.1 (39) | 1.8 (5) | 0.006c |
| Pneumonia | 3.9 (25) | 0.0 (0) | 0.001c |
| Empyema | 2.7 (17) | 0.4 (1) | 0.034c |
| Bronchial fistula | 1.4 (9) | 0.0 (0) | 0.064d |
| Acute interstitial pneumonia | 0.9 (6) | 0.0 (0) | 0.186d |
| Atelectasis | 0.5 (3) | 0.4 (1) | 1.000d |
| Miscellaneous, % (n) | |||
| Arrhythmia | 3.3 (21) | 1.8 (5) | 0.280c |
| Brain infarction | 1.1 (7) | 0.0 (0) | 0.109d |
| Wound infection | 0.3 (2) | 0.4 (1) | 1.000d |
| Reoperation | 3.0 (19) | 3.3 (9) | 0.836c |
Student’s t-test.
Mann–Whitney.
Chi-squared test.
Fisher’s exact test.
IQR: interquartile range; SD: standard deviation.
Univariate analysis for postoperative complication in 911 patients
| Variable | Reference | OR | 95% CI | P-Value | |
|---|---|---|---|---|---|
| Smoking cessation duration | Never smoker | Ex-smoker | 2.42 | 1.51–3.86 | <0.001 |
| Distant smoker | 3.58 | 2.09–6.11 | <0.001 | ||
| Recent smoker | 1.81 | 1.04–3.13 | 0.035 | ||
| Current smoker | 2.32 | 1.25–4.33 | 0.008 | ||
| Pack-years | Never smoker | <20 | 1.47 | 0.70–3.10 | 0.307 |
| 20–60 | 2.45 | 1.60–3.90 | <0.001 | ||
| >60 | 2.79 | 1.72–4.53 | <0.001 |
| Variable | Reference | OR | 95% CI | P-Value | |
|---|---|---|---|---|---|
| Smoking cessation duration | Never smoker | Ex-smoker | 2.42 | 1.51–3.86 | <0.001 |
| Distant smoker | 3.58 | 2.09–6.11 | <0.001 | ||
| Recent smoker | 1.81 | 1.04–3.13 | 0.035 | ||
| Current smoker | 2.32 | 1.25–4.33 | 0.008 | ||
| Pack-years | Never smoker | <20 | 1.47 | 0.70–3.10 | 0.307 |
| 20–60 | 2.45 | 1.60–3.90 | <0.001 | ||
| >60 | 2.79 | 1.72–4.53 | <0.001 |
Current smokers, <4 weeks; recent smokers, 4 weeks to 12 months; distant smokers, 12 months to 5 years; ex-smokers, >5 years.
CI: confidence interval; OR: odds ratio.
Univariate analysis for postoperative complication in 911 patients
| Variable | Reference | OR | 95% CI | P-Value | |
|---|---|---|---|---|---|
| Smoking cessation duration | Never smoker | Ex-smoker | 2.42 | 1.51–3.86 | <0.001 |
| Distant smoker | 3.58 | 2.09–6.11 | <0.001 | ||
| Recent smoker | 1.81 | 1.04–3.13 | 0.035 | ||
| Current smoker | 2.32 | 1.25–4.33 | 0.008 | ||
| Pack-years | Never smoker | <20 | 1.47 | 0.70–3.10 | 0.307 |
| 20–60 | 2.45 | 1.60–3.90 | <0.001 | ||
| >60 | 2.79 | 1.72–4.53 | <0.001 |
| Variable | Reference | OR | 95% CI | P-Value | |
|---|---|---|---|---|---|
| Smoking cessation duration | Never smoker | Ex-smoker | 2.42 | 1.51–3.86 | <0.001 |
| Distant smoker | 3.58 | 2.09–6.11 | <0.001 | ||
| Recent smoker | 1.81 | 1.04–3.13 | 0.035 | ||
| Current smoker | 2.32 | 1.25–4.33 | 0.008 | ||
| Pack-years | Never smoker | <20 | 1.47 | 0.70–3.10 | 0.307 |
| 20–60 | 2.45 | 1.60–3.90 | <0.001 | ||
| >60 | 2.79 | 1.72–4.53 | <0.001 |
Current smokers, <4 weeks; recent smokers, 4 weeks to 12 months; distant smokers, 12 months to 5 years; ex-smokers, >5 years.
CI: confidence interval; OR: odds ratio.
Multivariable analysis for postoperative complications
| Variable | Reference | Smokers-only cohort | Entire cohort | Entire cohort | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Model 1 (n = 635) | Model 2 (n = 907) | Model 3 (n = 903) | |||||||||
| OR | 95% CI | P-Value | OR | 95% CI | P-Value | OR | 95% CI | P-Value | |||
| Age | <60 | 60–75 | 1.45 | 0.75–2.80 | 0.275 | 1.84 | 1.02–3.31 | 0.043 | 2.01 | 1.13–3.59 | 0.018 |
| >75 | 1.69 | 0.79–3.61 | 0.177 | 2.05 | 1.06–3.99 | 0.036 | 2.25 | 1.18–4.29 | 0.014 | ||
| Gender | Male | Female | 0.50 | 0.25–1.01 | 0.055 | 0.58 | 0.35–0.97 | 0.039 | 0.61 | 0.36–1.04 | 0.071 |
| Charlson comorbidity index | ≦1 | >2 | 0.83 | 0.56–1.24 | 0.373 | 0.83 | 0.58–1.18 | 0.303 | 0.83 | 0.58–1.18 | 0.295 |
| Respiratory function | %VC ≧80 and %FEV1.0 ≧70 | %VC <80 or %FEV1.0 <70 | 1.81 | 1.13–2.88 | 0.013 | 1.81 | 1.17–2.81 | 0.009 | 1.76 | 1.14–2.71 | 0.011 |
| Clinical stage | l | ll | 1.81 | 1.15–2.87 | 0.011 | 1.64 | 1.10–2.50 | 0.017 | 1.58 | 1.04–2.41 | 0.033 |
| lll | 1.78 | 1.14–2.87 | 0.048 | 1.76 | 1.02–3.03 | 0.041 | 1.71 | 0.99–2.95 | 0.054 | ||
| Surgical procedure | Lobectomy | Others | 0.97 | 0.57–1.66 | 0.909 | 0.85 | 0.52–1.37 | 0.496 | 0.85 | 0.53–1.38 | 0.507 |
| Smoking status | Recent smoker | Current smoker | 1.32 | 0.68–2.56 | 0.409 | ||||||
| Distant smoker | 2.08 | 1.16–3.75 | 0.015 | ||||||||
| Ex-smoker | 1.50 | 0.87–2.59 | 0.142 | ||||||||
| Pack-years | <20 | 20–60 | 1.30 | 0.61–2.77 | 0.498 | ||||||
| >60 | 1.28 | 0.58–2.85 | 0.541 | ||||||||
| Smoking status | Never smoker | Current smoker | 1.36 | 0.65–2.82 | 0.416 | ||||||
| Recent smoker | 1.06 | 0.55–2.06 | 0.866 | ||||||||
| Distant smoker | 2.12 | 1.11–4.04 | 0.023 | ||||||||
| Ex-smoker | 1.44 | 0.80–2.57 | 0.221 | ||||||||
| Pack-years | 0 | <20 | 1.18 | 0.54–2.57 | 0.686 | ||||||
| 20–60 | 1.54 | 0.86–2.76 | 0.145 | ||||||||
| >60 | 1.63 | 0.87–3.08 | 0.130 | ||||||||
| Variable | Reference | Smokers-only cohort | Entire cohort | Entire cohort | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Model 1 (n = 635) | Model 2 (n = 907) | Model 3 (n = 903) | |||||||||
| OR | 95% CI | P-Value | OR | 95% CI | P-Value | OR | 95% CI | P-Value | |||
| Age | <60 | 60–75 | 1.45 | 0.75–2.80 | 0.275 | 1.84 | 1.02–3.31 | 0.043 | 2.01 | 1.13–3.59 | 0.018 |
| >75 | 1.69 | 0.79–3.61 | 0.177 | 2.05 | 1.06–3.99 | 0.036 | 2.25 | 1.18–4.29 | 0.014 | ||
| Gender | Male | Female | 0.50 | 0.25–1.01 | 0.055 | 0.58 | 0.35–0.97 | 0.039 | 0.61 | 0.36–1.04 | 0.071 |
| Charlson comorbidity index | ≦1 | >2 | 0.83 | 0.56–1.24 | 0.373 | 0.83 | 0.58–1.18 | 0.303 | 0.83 | 0.58–1.18 | 0.295 |
| Respiratory function | %VC ≧80 and %FEV1.0 ≧70 | %VC <80 or %FEV1.0 <70 | 1.81 | 1.13–2.88 | 0.013 | 1.81 | 1.17–2.81 | 0.009 | 1.76 | 1.14–2.71 | 0.011 |
| Clinical stage | l | ll | 1.81 | 1.15–2.87 | 0.011 | 1.64 | 1.10–2.50 | 0.017 | 1.58 | 1.04–2.41 | 0.033 |
| lll | 1.78 | 1.14–2.87 | 0.048 | 1.76 | 1.02–3.03 | 0.041 | 1.71 | 0.99–2.95 | 0.054 | ||
| Surgical procedure | Lobectomy | Others | 0.97 | 0.57–1.66 | 0.909 | 0.85 | 0.52–1.37 | 0.496 | 0.85 | 0.53–1.38 | 0.507 |
| Smoking status | Recent smoker | Current smoker | 1.32 | 0.68–2.56 | 0.409 | ||||||
| Distant smoker | 2.08 | 1.16–3.75 | 0.015 | ||||||||
| Ex-smoker | 1.50 | 0.87–2.59 | 0.142 | ||||||||
| Pack-years | <20 | 20–60 | 1.30 | 0.61–2.77 | 0.498 | ||||||
| >60 | 1.28 | 0.58–2.85 | 0.541 | ||||||||
| Smoking status | Never smoker | Current smoker | 1.36 | 0.65–2.82 | 0.416 | ||||||
| Recent smoker | 1.06 | 0.55–2.06 | 0.866 | ||||||||
| Distant smoker | 2.12 | 1.11–4.04 | 0.023 | ||||||||
| Ex-smoker | 1.44 | 0.80–2.57 | 0.221 | ||||||||
| Pack-years | 0 | <20 | 1.18 | 0.54–2.57 | 0.686 | ||||||
| 20–60 | 1.54 | 0.86–2.76 | 0.145 | ||||||||
| >60 | 1.63 | 0.87–3.08 | 0.130 | ||||||||
Current smokers, <4 weeks; recent smokers, 4 weeks to 12 months; distant smokers, 12 months to 5 years; ex-smokers, >5 years.
CI: confidence interval; %FEV1.0: % forced expiratory volume in 1 s; OR: odds ratio; %VC: % vital capacity.
Multivariable analysis for postoperative complications
| Variable | Reference | Smokers-only cohort | Entire cohort | Entire cohort | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Model 1 (n = 635) | Model 2 (n = 907) | Model 3 (n = 903) | |||||||||
| OR | 95% CI | P-Value | OR | 95% CI | P-Value | OR | 95% CI | P-Value | |||
| Age | <60 | 60–75 | 1.45 | 0.75–2.80 | 0.275 | 1.84 | 1.02–3.31 | 0.043 | 2.01 | 1.13–3.59 | 0.018 |
| >75 | 1.69 | 0.79–3.61 | 0.177 | 2.05 | 1.06–3.99 | 0.036 | 2.25 | 1.18–4.29 | 0.014 | ||
| Gender | Male | Female | 0.50 | 0.25–1.01 | 0.055 | 0.58 | 0.35–0.97 | 0.039 | 0.61 | 0.36–1.04 | 0.071 |
| Charlson comorbidity index | ≦1 | >2 | 0.83 | 0.56–1.24 | 0.373 | 0.83 | 0.58–1.18 | 0.303 | 0.83 | 0.58–1.18 | 0.295 |
| Respiratory function | %VC ≧80 and %FEV1.0 ≧70 | %VC <80 or %FEV1.0 <70 | 1.81 | 1.13–2.88 | 0.013 | 1.81 | 1.17–2.81 | 0.009 | 1.76 | 1.14–2.71 | 0.011 |
| Clinical stage | l | ll | 1.81 | 1.15–2.87 | 0.011 | 1.64 | 1.10–2.50 | 0.017 | 1.58 | 1.04–2.41 | 0.033 |
| lll | 1.78 | 1.14–2.87 | 0.048 | 1.76 | 1.02–3.03 | 0.041 | 1.71 | 0.99–2.95 | 0.054 | ||
| Surgical procedure | Lobectomy | Others | 0.97 | 0.57–1.66 | 0.909 | 0.85 | 0.52–1.37 | 0.496 | 0.85 | 0.53–1.38 | 0.507 |
| Smoking status | Recent smoker | Current smoker | 1.32 | 0.68–2.56 | 0.409 | ||||||
| Distant smoker | 2.08 | 1.16–3.75 | 0.015 | ||||||||
| Ex-smoker | 1.50 | 0.87–2.59 | 0.142 | ||||||||
| Pack-years | <20 | 20–60 | 1.30 | 0.61–2.77 | 0.498 | ||||||
| >60 | 1.28 | 0.58–2.85 | 0.541 | ||||||||
| Smoking status | Never smoker | Current smoker | 1.36 | 0.65–2.82 | 0.416 | ||||||
| Recent smoker | 1.06 | 0.55–2.06 | 0.866 | ||||||||
| Distant smoker | 2.12 | 1.11–4.04 | 0.023 | ||||||||
| Ex-smoker | 1.44 | 0.80–2.57 | 0.221 | ||||||||
| Pack-years | 0 | <20 | 1.18 | 0.54–2.57 | 0.686 | ||||||
| 20–60 | 1.54 | 0.86–2.76 | 0.145 | ||||||||
| >60 | 1.63 | 0.87–3.08 | 0.130 | ||||||||
| Variable | Reference | Smokers-only cohort | Entire cohort | Entire cohort | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Model 1 (n = 635) | Model 2 (n = 907) | Model 3 (n = 903) | |||||||||
| OR | 95% CI | P-Value | OR | 95% CI | P-Value | OR | 95% CI | P-Value | |||
| Age | <60 | 60–75 | 1.45 | 0.75–2.80 | 0.275 | 1.84 | 1.02–3.31 | 0.043 | 2.01 | 1.13–3.59 | 0.018 |
| >75 | 1.69 | 0.79–3.61 | 0.177 | 2.05 | 1.06–3.99 | 0.036 | 2.25 | 1.18–4.29 | 0.014 | ||
| Gender | Male | Female | 0.50 | 0.25–1.01 | 0.055 | 0.58 | 0.35–0.97 | 0.039 | 0.61 | 0.36–1.04 | 0.071 |
| Charlson comorbidity index | ≦1 | >2 | 0.83 | 0.56–1.24 | 0.373 | 0.83 | 0.58–1.18 | 0.303 | 0.83 | 0.58–1.18 | 0.295 |
| Respiratory function | %VC ≧80 and %FEV1.0 ≧70 | %VC <80 or %FEV1.0 <70 | 1.81 | 1.13–2.88 | 0.013 | 1.81 | 1.17–2.81 | 0.009 | 1.76 | 1.14–2.71 | 0.011 |
| Clinical stage | l | ll | 1.81 | 1.15–2.87 | 0.011 | 1.64 | 1.10–2.50 | 0.017 | 1.58 | 1.04–2.41 | 0.033 |
| lll | 1.78 | 1.14–2.87 | 0.048 | 1.76 | 1.02–3.03 | 0.041 | 1.71 | 0.99–2.95 | 0.054 | ||
| Surgical procedure | Lobectomy | Others | 0.97 | 0.57–1.66 | 0.909 | 0.85 | 0.52–1.37 | 0.496 | 0.85 | 0.53–1.38 | 0.507 |
| Smoking status | Recent smoker | Current smoker | 1.32 | 0.68–2.56 | 0.409 | ||||||
| Distant smoker | 2.08 | 1.16–3.75 | 0.015 | ||||||||
| Ex-smoker | 1.50 | 0.87–2.59 | 0.142 | ||||||||
| Pack-years | <20 | 20–60 | 1.30 | 0.61–2.77 | 0.498 | ||||||
| >60 | 1.28 | 0.58–2.85 | 0.541 | ||||||||
| Smoking status | Never smoker | Current smoker | 1.36 | 0.65–2.82 | 0.416 | ||||||
| Recent smoker | 1.06 | 0.55–2.06 | 0.866 | ||||||||
| Distant smoker | 2.12 | 1.11–4.04 | 0.023 | ||||||||
| Ex-smoker | 1.44 | 0.80–2.57 | 0.221 | ||||||||
| Pack-years | 0 | <20 | 1.18 | 0.54–2.57 | 0.686 | ||||||
| 20–60 | 1.54 | 0.86–2.76 | 0.145 | ||||||||
| >60 | 1.63 | 0.87–3.08 | 0.130 | ||||||||
Current smokers, <4 weeks; recent smokers, 4 weeks to 12 months; distant smokers, 12 months to 5 years; ex-smokers, >5 years.
CI: confidence interval; %FEV1.0: % forced expiratory volume in 1 s; OR: odds ratio; %VC: % vital capacity.
DISCUSSION
This study aimed to analyse the effect of smoking cessation period on the incidence of complications after lung cancer surgery. We found that compared with never smokers, smoker had about 5 times higher rate of pulmonary complications. The smokers were classified into 4 groups according to the duration of smoking cessation. The distant smokers had the highest number of comorbidities and had more postoperative complications. The risk for postoperative complications tended to be higher in current smokers than in recent smokers. Although there was a smoking volume-dependent relationship with the risk for postoperative complications, this was not significant.
In this study, the percentage of current smokers (9.6%) was lower than that reported in previous studies [16, 17]. However, surprisingly, as many as 20% of the current smokers continued to smoke despite the history of malignant disease. Similarly, a previous anonymous cross-sectional study reported that a significant proportion of cancer survivors continued to smoke [18], suggesting the need for persistent smoking cessation encouragement after treatment.
In 2020, the World Health Organization published a summary of smoking knowledge and concluded that prolonged smoking abstinence period, ideally >4 weeks, was consistently associated with improved postoperative outcomes [6]. That recommendation was based on a synthesis of the findings of several meta-analyses. However, only few thoracic surgery studies were included in those meta-analyses. The study by Zaki et al. [19] that included only randomized controlled trials did not include a thoracic surgery study, and the study by Grønkjær et al. [7], which combined >100 observational studies, included only 1.8% lung surgeries. An evidence-based study that reviewed thoracic procedures concluded that although preoperative smoking cessation was beneficial, the effective duration of cessation remained controversial [20]. Previous studies have shown that compared with never smokers, smokers had two- to ten-fold higher complication rates [11, 21]; this result was consistent with those of this study. Several single-centre retrospective studies reported that compared with never smokers, patients with longer smoking cessation periods had lower complication rates; however, the analyses did not adjust for respiratory function tests and other factors [5, 21, 22].
The favourable changes after smoking cessation are thought to be secondary to reduced sputum production or decreased level of inflammatory cytokines [11, 12]. We hypothesized that if these positive physical changes after short-term smoking cessation contributed to a reduction in complications, the OR should be lower with a longer duration of preoperative smoking cessation. However, our results could not find that smoking cessation duration did not affect the risk for postoperative complications in a time-dependent manner. Notably, the highest risk was in the distant smoker group, which included those who had stopped smoking for >1 year. In this study population, interstitial pneumonia, cardiovascular disease and diabetes were observed most frequently in distant smokers and ex-smokers, who may have stopped smoking after being diagnosed with these diseases or having physical symptoms. In contrast, we presumed that current smokers and recent smokers have fewer comorbidities and have a strong enough physical condition to continue smoking. This suggests that risk factors, including patients’ underlying conditions, might not have been fully adjusted; this might have contributed to the lack of clarity in terms of the relationship between preoperative smoking cessation duration and postoperative complications.
The unique point of thoracic surgery is based on the fact that the lungs are one of the most susceptible organs to the effects of smoking. A previous prospective study examining pulmonary function tests at 1 year postoperative as well as complications reported no positive effect of a short period of smoking cessation before surgery [23]. Preoperative respiratory function may be more contributory and negate the positive effects of a short smoking cessation period. Some previous studies did not include respiratory function in their multivariable analyses; therefore, differences in background factors may not have been fully accounted for. In a study on >2000 patients from a database from the Society of Thoracic Surgeons General Thoracic Surgery, amount of smoking not the duration of preoperative smoking cessation was associated with the occurrence of postoperative complications [10]. The results of the present study showed that the occurrence of complications was related more to the amount of smoking than to the duration of preoperative smoking cessation and that low lung function was the major risk factor for postoperative complications after thoracic surgery. Although this study was a single-center retrospective study, we included a wide range of patients with lung cancer who underwent curative-intent surgery, which may ensure a certain degree of external validity.
Limitations
This study had several limitations. First, the single-centre retrospective design had an inherent risk of selection bias. Second, smoking status was based on self-reported information from patients. Self-reported smoking status has a tendency to be lower than the actual and may have resulted in over reporting of smoking cessation period and under reporting of pack-years [24]. Third, the number of cigarettes smoked widely changes over the smoker’s lifetime, but we could not factor this effect due to a lack of data. Fourth, during the initial interview at the time of surgical referral, we asked all patients about their smoking status. However, even smokers were not asked about their smoking cessation date and for an update of their smoking cessation status at the time of admission for surgery. Therefore, we could not show a detailed classification of smoking cessation before surgery. Finally, the effects of smoking on the lungs are related not only to the years of smoking and number of pack-years [25] but also to the smoking method (i.e. whether or not the smoke is inhale); this factor could not be examined in this study.
CONCLUSION
In conclusion, healthcare providers should encourage patients to stop smoking at any point in time in the clinical setting. However, the evidence-based smoking cessation duration that can reduce the incidence of complications after thoracic surgery remains unclear. Therefore, postponing the date of surgery to allow time for smoking cessation should be carefully considered in patients with advanced lung cancer and critical indications for surgery.
ACKNOWLEDGEMENTS
The authors thank all the staff members of the Department of Thoracic Surgery, Nagoya Graduate School of Medicine, and Dr. Kota Ono (https://ono-biostat-consulting.com/), who is an employee at AbbVie GK.
Conflict of interest: none declared.
Data Availability Statement
The data underlying this article cannot be shared publicly to maintain the privacy of individuals who participated in the study. The data will be shared upon reasonable request to the corresponding author.
Author contributions
Yuka Kadomatsu: Conceptualization; Data curation; Formal analysis; Writing—original draft; Writing—review & editing. Tomoshi Sugiyama: Conceptualization; Data curation. Keiyu Sato: Data curation. Keita Nakanishi: Data curation. Harushi Ueno: Data curation. Masaki Goto: Data curation. Naoki Ozeki: Data curation; Writing—review & editing. Shota Nakamura: Data curation. Koichi Fukumoto: Data curation; Writing—review & editing. Toyofumi Fengshi Chen-Yoshikawa: Conceptualization; Investigation; Resources; Supervision; Validation; Writing—review & editing.
Reviewer information
European Journal of Cardio-Thoracic Surgery thanks Frank A. Baciewicz Jr, René Horsleben Petersen and the other, anonymous reviewer(s) for their contribution to the peer review process of this article.
