Conditional relative survival among long-term survivors of adolescent and young adult cancers.

BACKGROUND: Many studies have examined long-term outcomes after childhood cancer, but few address outcomes for adolescent and young adult (AYA; those aged 15-39 years) cancer survivors. Conditional survival reflects changing mortality risk with time since cancer diagnosis and is a useful measure for planning long-term follow-up care.
METHODS: Using the Surveillance, Epidemiology, and End Results registry 9 database, the authors identified a cohort of AYA patients diagnosed with a first malignant cancer between 1973 and 2009 and followed through 2014. They estimated 5-year relative survival at the time of diagnosis and at each additional year survived up to 25 years after diagnosis, conditional on the individual being alive at the beginning of that year.
RESULTS: A total of 205,954 AYA patients with cancer were identified. Thyroid cancer, melanoma, testicular cancer, breast cancer, lymphoma, leukemia, and central nervous system (CNS) tumors comprised 67% of all cancers. For all cancers combined, 5-year relative survival was 84.5% (95% confidence interval, 84.3%-84.7%) at 1 year after diagnosis and 94.0% (95% CI, 93.9%-94.2%) at 5 years. The relative survival first exceeded 95%, reflecting minimal excess mortality compared with the general population, at 7 years. Patients with thyroid cancer, testicular cancer, melanoma, and breast cancer reached a relative survival of >95% at the time of diagnosis and at 1, 3, and 18 years after diagnosis, respectively. Estimates for those with Hodgkin lymphoma and leukemia were >95% at 6 and 13 years, respectively, but declined to <95% at 20 years. AYA individuals with CNS tumors did not reach 95% by 25 years after diagnosis.
CONCLUSIONS: For AYA survivors of breast cancer, CNS tumors, and hematologic malignancies, long-term excess mortality should be considered when planning follow-up care. Cancer 2018;124:3037-43.