(a) Spaghetti plot: size of NF-pNETs <2 cm over time. (b) Modeled growth of NF-pNETs <2 cm. Growth curve NF-pNETs <2 cm. Coefficients derived from linear mixed models analysis. Mathematic representation of the model: tumor size in mm = 9.7 + (0.37 * time in years). (c) Spaghetti plot: size of progressive NF-pNETs <2 cm over time. (d) Modeled growth of progressive NF-pNETs <2 cm. Growth curve of progressive vs stable NF-pNETs <20 mm. Coefficients derived from mixed models analysis. Mathematic representation of the model: Progressive: tumor size in mm = 9.1 + (1.55 * time in years). Stable: tumor size in mm = 9.9 + (−0.01 * time in years). (e) Modeled growth of progressive NF-pNETs <20 mm stratified by genotype. Growth curve of progressive NF-pNETs <2 cm stratified by genotype. Coefficients derived from mixed models analysis. P-value for interaction 0.09. Mathematical representation of the model: Missense: tumor size in mm = 9.6 + (2.02 * time in years). Nonsense/frameshift: tumor size in mm = 8.3 + (1.14 * time in years).