Epidemiological analysis of second primary malignant neoplasms in cancer survivors aged 85 years and older: a SEER data analysis (1975–2016)

Cancer burden in patients aged 85 years and older has rapidly increased accompanying the decrease in mortality, which is raising the concern of developing second primary malignant neoplasms (SPM). This study aimed to investigate the epidemiology of the SPM in this population in the US by using the surveillance, epidemiology, and end results database (1975–2016). The cumulative incidence of developing a SPM was calculated by the Fine and Gray model. Standardized incidence ratios (SIR) were calculated via Poisson regression. The relative post-SPM survival rate was calculated by the Kaplan–Meier method. Male patients with skin melanoma, kidney and renal pelvis and urinary bladder cancers had high cumulative incidences (15.32%, 13.55%, and 12.26%, respectively) and increased SIRs (1.47, 1.44, and 1.16, respectively) for developing SPMs. Female patients with skin melanoma and urinary bladder cancers had high cumulative incidences (10.18% and 7.87%, respectively) and increased SIRs (1.34 and 1.18, respectively). In general, the incidence of SPM cases increased over time. The median latency ranged from 17 to 37 months. A less than 50% of patients had 1-year post-SPM survival. In conclusion, some of these patients had an increased risk of the SPM, with poor survival.