Letter to the Editor Free

The paper “Adjuvant Radioactive Iodine Therapy Is Associated With Improved Survival for Patients With Intermediate-Risk Papillary Thyroid Cancer” by Ruel et al reports that patients with intermediate-risk papillary thyroid cancer (PTC) are more likely to improve their survival if they had postsurgical radioablative iodine therapy (1). The authors attribute this survival to the possible effect of radioiodine (RAI) and recommend that this group of patients should be considered for RAI therapy. The following points need to be addressed when interpreting the results of the study.

First, the paper did not take into account the physician's bias and preferences when dealing with patients with intermediate risk. Chances are the cases that doctors deemed to be more invasive among the intermediate group would end up with RAI. As a result, those patients whom the treating doctors deemed as having poorer prognosis end up having RAI.

Secondly, the authors reported overall survival and not mortality or morbidity for PTC. The modified Charlson/Deyo scoring system 1992 (2) assessed only the survival outcome in both the RAI and non-RAI groups. With the relatively good prognosis of intermediate PTC, the survival data alone in both the RAI and non-RAI groups do not provide any information on the quality of life and morbidities, especially in the older patients. Similarly, the absence of data on specific causes of mortality among the patients who had RAI as well as those not receiving RAI did not allow the examination of factors associated with mortality. Stroup et al (3) suggested that age at diagnosis remains one of the strongest prognostic factors for thyroid cancer survival in women with differentiated thyroid cancer. These women by virtue of their increased age are also likely to die from other causes, including cardiovascular diseases and other cancers. Therefore, in-depth quality of life and morbidity assessments as well as an understanding of the disease-specific causes of mortality would be more beneficial. Such data would facilitate effective care for other comorbid conditions to reduce mortality from these causes.

Thirdly, this study captured data ranging from 1998–2008 with follow-up time of about 6 years. There has been a shift in the paradigm of management of intermediate PTC after the publication of the Revised American Thyroid Association Management Guideline for Patients With Thyroid Nodules and Differentiated Thyroid Cancer (4). During follow-up, patients who entered the study toward the end of data collection were subjected to treatment bias. Because clinical decisions are subjected to physician preferences, the presence of such details further mitigates the risk of biasness in the selection of treatment modalities.

RAI ablation is usually recommended for patients with more aggressive histological variants of PTC and for those with primary tumors larger than 2 cm (5). In more than half (51%) of the patients analyzed, tumor size was 2 cm or less. This represents “lower risk” rather than the so-called “intermediate risk” that had been assigned to these patients.

Finally, the evidence provided by the authors is more consistent with the overuse of adjunct RAI in this population of patients with intermediate risk. Given the good prognosis of intermediate PTC, the risk of overuse of postsurgical adjunct RAI outweighed the benefits.

Disclosure Summary: The authors have nothing to disclose.

Abbreviations

 
• PTC

  papillary thyroid cancer

 
• RAI

  radioiodine.

References