Risk for second primary cancers among pediatric and young adult melanoma survivors

Background/Objectives: Second primary cancers (SPCs) are a leading cause of morbidity and mortality among cancer survivors. In this study, we aimed to characterize the incidence of SPCs among pediatric and young adult survivors of CM. Methods: Using the Surveillance, Epidemiology, and End Results Program data spanning 2000–2018, we calculated standardized incidence ratios (SIR) to assess SPC risk in all pediatric (0–18 years) and young adult (19–29 years) patients with a first primary cancer diagnosis of CM. Results: Of 7,169 total CM survivors, 632 (8.82%) developed a SPC, corresponding to a 5-fold increased risk (standardized incidence ratio [SIR] 4.98; 95% confidence interval [CI] 4.60–5.38) compared to the general population. There was a highly elevated risk for second primary melanoma across all age groups (SIR 32.5; 95% CI 29.7–35.6), constituting the majority of SPC diagnoses (N = 485). Infants diagnosed with CM before 1 year of age had the highest risk for any SPC (SIR 164; 95% CI 19.8–592) and young adults diagnosed at 25–29 years had the lowest risk (SIR 4.64; 95% CI 4.19–5.13). SPC incidence was highest within the first year of CM diagnosis (SIR 27.5; 95% CI 23.7–31.6) and progressively decreased with time. Conclusions: Variation exists in the incidence and type of SPC according to age among pediatric and young adult survivors of CM.