Risk of second primary cancers among survivors of gynecological cancers.

OBJECTIVE

Survivors of gynecologic cancers have an increased risk of developing second primary cancers (SPC); however it is unclear which sites have higher risks. We aimed to ascertain risk of SPC among survivors of gynecological cancer, and identify anatomic sites at risk of SPC.

METHODS

We queried the Surveillance, Epidemiology and End Results database (2000-2016) for confirmed cases of index gynecological (cervix uteri [cervical], corpus and uterus [endometrial], ovarian, vaginal, and vulvar) cancers. Risk of SPC was estimated using standardized incidence ratios (SIRs: observed/expected cases) and excess absolute risks (EARs: observed - expected cases) per 10,000 person-years at risk (PYR). SIRs and EARs were stratified by index anatomic site and latency interval.

RESULTS

Among the cohort of 301,210 gynecological cancer survivors, 19,005 (6.31%) developed an SPC (SIR = 1.16; 95% CI, 1.15-1.18 and EAR = 17.2 cases per 10,000 PYR) compared with the general population. All gynecological cancer survivors (except survivors of ovarian) had a significant risk of developing SPC (SIR range 1.06-2.16), with survivors of vulvar cancer having the highest risk (SIR = 2.16; 95% CI, 2.06-2.27; EAR = 139.5 per 10,000 PYR). Risk of SPC was highest within the first 5 years post-diagnosis for survivors of cervical, vulvar and vaginal cancers.

CONCLUSIONS

While most index gynecological cancer sites are associated with increased risk of SPC, risk is highest among survivors of vulvar cancer. These findings have the potential to inform lifelong surveillance recommendations for gynecological cancer survivors.