Subsequent primary cancers among survivors of adolescent and young adult onset cancers in the United States.

10604 Background: Adolescent and young adult (AYA) cancer survivors are at increased risk of subsequent primary cancer (SPC); however, a comprehensive examination of risk patterns across cancer types is lacking in the U.S. Methods: SPC incidence and mortality was calculated among >1-year cancer survivors aged 15 to 39 years at first primary cancer (FPC) diagnosis during 1992-2016 in 12 Surveillance, Epidemiology, and End Results registries. Rates were expressed as number of cases/deaths per 10,000 person-years and compared with those expected in the general population using standardized incidence (SIR) and standardized mortality ratios (SMR). Results: Among 202,440 survivors of AYA-onset cancers (mean age at FPC diagnosis, 31.8 years; 60.7% women), 6,675 SPC cases (34.3 per 10,000) and 3,786 SPC deaths (19.4 per 10,000) occurred during 1,955,119 person-years of follow-up (mean, 9.7 years), corresponding to an SIR of 1.58 (95%CI = 1.54-1.62) and SMR of 4.19 (95%CI = 4.06-4.33. In men, overall incidence and mortality SPC rates were statistically significantly higher for each of 21 FPC types compared with risks in the general population, except for thyroid cancer mortality. In women, risk was statistically significantly higher for 14/23 FPC types for incidence and 19/23 FPC types for mortality. SIRs were highest in survivors of pancreatic cancer (SIR = 5.68, 95% CI = 2.94-9.93; 84 per 10,000), Kaposi sarcoma (SIR = 5.15, 95%CI = 4.62-5.73; 116 per 10,000) and liver cancer (SIR = 4.97, 95%CI = 2.57-8.68; 68.4 per 10,000) in men, and acute lymphoid leukemia (SIR, 3.27, 95% CI = 2.22-4.64; 49.5 per 10,000), Hodgkin lymphoma (SIR = 2.47, 95% CI = 2.22-2.73; 51.6 per 10,000), and bone sarcoma (SIR = 2.41, 95%CI = 1.80-3.16; 47.6 per 10,000) in women. SMRs were highest in survivors of pancreatic cancer, acute lymphoid leukemia, and stomach cancer in men, and liver cancer, acute lymphoid leukemia, and soft tissue sarcoma in women. Conclusions: Overall and type-specific risk patterns of SPCs among AYA cancer survivors differ considerably across FPC type, highlighting the need for targeted approaches for cancer prevention and surveillance in survivorship care planning.