Abstract 3713: Second malignant neoplasms after non-CNS embryonal tumors in North America

Abstract

Abstract Background: Childhood cancer survivors are known to face an increased risk of adverse medical conditions related to the initial disease or cancer treatment; however, few studies have quantified the risk of second malignant neoplasms (SMNs) among survivors of childhood non-CNS embryonal cancer due to its rarity. In this study, we combined data from the U.S. and Canada to investigate the risk of SMNs. Methods: Data from 13,107 survivors of childhood non-CNS embryonal tumors reported to the Surveillance Epidemiology and End Results (SEER) program in the U.S. and 8 population-based cancer registries in Canada (between 1973 to 2010) were analyzed. We calculated standardized incidence ratios (SIRs) for all types of second primaries by type of first primary, age at first cancer diagnosis, and follow-up duration. Expected numbers of SMNs were obtained by applying age-, sex-, calendar year-, and registry-specific cancer incidence rates to person-years contributed by these cancer survivors. Results: One hundred and ninety SMNs were reported over 134,548 person-years of follow-up, with bone and joint cancer and leukemia being the most common SMNs (19% and 16% respectively). The SIR for all SMNs combined was 6.4 (95% CI: 5.53-7.35). Most site-specific SIRs were significantly increased, ranging from 36.4 (95% CI: 25.5-49.2) for bone and joint cancer, to 3.1 (95% CI: 1.54-5.2) for brain tumor. Among all the survivors, those who survived rhabdomyosarcoma carried the greatest risk of SMN development with SIR of 11.5 (95% CI: 8.7-14.6). Bone and joint tumors were mostly seen among retinoblastoma survivors, reflecting a markedly risk of 139.3 (95% CI: 85-207). When stratified by follow-up period, we observed that the risk patterns varied by SMN site. For example, the risk for a second malignancy in the thyroid remained significantly increased even after 20 years of follow-up, whereas the elevated risk of secondary leukemia persisted for 10 years but decreased rapidly afterwards. Details of stratified analyses by first primary tumor site, age at first diagnosis, and follow-up duration will be presented. Conclusion: Survivors of childhood non-CNS embryonal tumors have increased risks of developing SMNs compared to the general population. Increased surveillance may explain the elevated risks within the first few years of the initial diagnosis, but treatment effects and shared etiology most likely account for the excess risk later in life. Citation Format: Xuchen Zong, Jason D. Pole, Paul Grundy, Salaheddin M. Mahmud, Louise Parker, Rayjean J. Hung. Second malignant neoplasms after non-CNS embryonal tumors in North America. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3713. doi:10.1158/1538-7445.AM2015-3713