Is the increased risk of subsequent neoplasm lessening among survivors of childhood cancer?

The risk of subsequent malignancies among 5-year survivors of childhood cancer remains increased among those who had an initial cancer diagnosis in the 1990s. However, their risk is lower than the risk in survivors who were given an initial diagnosis in the 1970s and 1980s. The difference corresponds to reductions in the therapeutic radiation dose and the cumulative chemotherapy dose. (LOE = 2b)

Turcotte LM, Liu Q, Yasui Y, et al. Temporal trends in treatment and subsequent neoplasm risk among 5-year survivors of childhood cancer, 1970-2015. JAMA 2017;317(8):814-824.  [PMID:28245323]

Cohort (retrospective)

Government

Population-based

Cancer treatments increase the risk of subsequent malignancies in adult survivors of childhood cancer. These investigators evaluated data obtained from a large retrospective cohort study with long-term follow-up of 5-year survivors of childhood cancer that was diagnosed in both the United States and Canada between January 1, 1970, and December 31, 1999. Patients were younger than 21 years at initial diagnosis of cancer. Subsequent malignancies were identified by self-report or next-of-kin report or death certificates and confirmed by pathology reports and medical records. Cancer therapies were also determined by review of original medical records. Of the original cohort of 35,923 survivors, 24,362 (68%) consented to follow-up. Follow-up ranged from 15.7 years for those with cancer diagnosed in the 1990s to 27.6 years for the 1970s group. After 15 years of follow-up, the cumulative incidence of subsequent malignancies was 2.9% (95% CI 2.5% - 3.3%) among patients with cancer diagnosed in the 1970s, 2.4% (95% CI, 2.1%-2.7%) among those with cancer diagnosed in the 1980s, and 1.5% (1.3% - 1.8%) among those with cancer diagnosed in the 1990s. The most frequently observed subsequent malignancies were breast and thyroid cancer. Radiation therapy as a component of treatment decreased from 77% of survivors in the 1970s to 54% in the 1980s and to 33% in the 1990s. The median cumulative doses of chemotherapy for most agents, except platinum, also similarly decreased.