Risk of second primary malignancies of adolescent and young adult patients with germ cell cancer: A US population-based analysis.

PURPOSE: Germ cell cancer (GCC) is a group of neoplasms with heterogeneity. Predominant in young adults, GCC potentially mitigates a high number of productive years of life lost. Indeed, long-term side effects have arisen as a problem in GCC survivors, especially in adolescent and young adult (AYA) subgroup. The objective of this study is to delineate survival and second primary malignancies (SPMs) in AYA patients with GCC.

METHODS

We used US population-based Surveillance, Epidemiology and End Results (SEER) 18 Regs Custom Data (1976-2016 varying) and SEER 9 Regs Research Data, November 2019 Sub (1975-2017) for survival analysis and SPM analysis, respectively.

RESULTS

Overall, 5-, 10- and 20-year overall survival rates for AYA patients with GCC were 93%, 91.3%, and 86.9%, respectively. Compared with the general population, a significantly higher risk of SPMs was observed in multiple sites, especially stomach, (standardized incidence ratio [SIR] = 2.94), pancreas (SIR = 3.72), intrahepatic bile duct (SIR = 3.12), soft tissue including heart (SIR = 4.65), leukemia (SIR = 3.70), and testis (SIR = 562.18). The excess risks to develop leukemia were even higher in those with primary mediastinal GCC (SIR = 69.50, P < 0.05, 95% confidence interval = 30.00-136.94). Multivariate analysis indicated age of diagnosis, primary site, race, receipt of radiotherapy, and histological subtype independently correlated with risk of SPMs.

CONCLUSION

The present study provides risk factors of SPM in AYA patients with GCC, which could facilitate the individualization of long-term surveillance in this population.