Risk of Late Mortality and Second Malignant Neoplasms among 5-Year Survivors of Young Adult Cancer: A Report of the Childhood, Adolescent, and Young Adult Cancer Survivors Research Program

We conducted a population-based retrospective study to assess the long-term risks of overall and cause-specific mortality and second malignant neoplasm (SMN) among survivors of young adult cancer compared to the risk in British Columbia (BC) population and to evaluate the effects of demographic and clinical factors on risk. 1248 5-year survivors of young adult cancer diagnosed 1970–1995 between 20 and 24 years of age were identified from the BC Cancer Registry and followed to the end of 2007. Standardized mortality ratios (SMRs) and standardized incidence ratios (SIRs) were calculated. The Cox proportional hazards model was used to estimate the effects of different demographic and disease-related characteristics on the risk of death and SMN. A total of 138 deaths and 62 SMNs were observed during follow-up. The overall SMR was 5.9 (95% CI 4.9–6.9) and the absolute excess risk was 5.3 per 1,000 person-years. The overall SIR was 3.0 (95% CI 2.3–3.8). Treatment with radiation resulted in increased risks of death and SMN. These observed increased risks emphasize the importance of prevention, surveillance, and treatment of late effects in survivors of young adult cancers. 1. Introduction Advances in therapy for young adult cancers have led to an increase in the relative 5-year survival rate from 71% in 1975 to 87% in 2007 [1]. This has created a growing population of young adult cancer survivors. In Canada, presently more than 150,000 Canadians are survivors of a young adult cancer diagnosed since 1980 [2]. Long-term survivors of young adult cancer may face serious health risks including an increased risk of a second malignant neoplasm (SMN), excess late mortality, and functional impairment of multiple organ systems [3, 4]. Previous studies have shown that survivors of childhood and adolescent cancer have increased mortality risks, compared with the general population [5–10]. Death in these survivors is mainly due to the original cancer, followed by deaths due to second malignant neoplasm (SMN) and noncancer causes [5, 7, 8, 11, 12]. Long-term survivors of childhood and adolescent cancer are also at risk for the development of an SMN. This risk is likely to be the consequence of multiple factors, including environment factors and genetic susceptibility related to the original diagnosis, the treatment used, immunosuppression, and hormonal factors [3]. Previous studies have reported that the relative risk of developing SMN varies between 2.4 and 6.1 in this group [13], depending on characteristics of the study population, the types of SMN considered, the