Rate of second primary tumors following diagnosed choriocarcinoma: A SEER analysis (1973-2010)

Objective Approximately 1 in 6 of new cancers has been reported to represent a second primary tumor (SPT). Choriocarcinomas (CCs) are of interest in regard to the rate of SPTs because of the potential exposure to carcinogenic therapy and reports of the benefits of its high human gonadotropin (hCG) levels on cancer incidence. Methods We used the Surveillance, Epidemiology, and End Results (SEER) database to identify patients with gestational CC who subsequently developed a SPT. This is a retrospective study, following a cohort of patients during the period 1973-2010. Results We found 818 patients with primary gestational CC. Nineteen patients had a SPT after the CC. Occurrence of several types of cancer resulted significantly higher when compared to the incidence rate in the general population. In particular the highest incidence rate ratios (IRRs) were registered for acute myeloid leukemia (AML) (6.3) and thyroid cancer (2.6). The expected rate of lung, breast, colorectal and uterine corpus cancers instead resulted lower than the rate in the general population. Regarding the IRR in the population under 50 years of age, the higher IRRs were related to AML (20) and non-Hodgkin lymphoma (NHL) (5). Conclusion The association of thyroid cancer and CC has not been described previously. Increases in hematological cancer following CC lend further support to the established data. The decrease in breast and colon cancers in all age groups supports past data and decreases in uterine and lung cancers are new observations meriting further study.