Risk and survival of third primary cancers in a population-based cohort of patients with a cervical, endometrial, or ovarian cancer

Purpose

Multiple primary cancers are relevant outcomes among survivors of gynecological cancers, contributing to the overall cancer burden and having a potential impact on the management of each primary cancer. This study aimed to estimate the risk and survival of third primary cancers (TPCs) among females with a cervical, endometrial, or ovarian first primary cancer (FPC).

Methods

Patients with a cervical, endometrial, or ovarian FPC from the Portuguese North Region Cancer Registry, diagnosed between 2000 and 2010 (n = 5846), were followed for a TPC (December 31, 2015) and death from any cause (December 31, 2023). The cumulative incidence of TPCs and mortality was estimated. Patients with a TPC were matched (1:1) to patients without a TPC (FPC + second primary cancer [SPC] only) to compare survival.

Results

Overall, 29 (0.5% of FPCs and 5.4% of SPCs) TPCs were diagnosed. The most common sites were digestive organs (n = 9) followed by breast and urinary tract cancers (n = 4 each). Among all FPCs, the 10-year cumulative incidence (95% confidence interval [CI]) of a TPC was 0.5% (0.3%–0.7%) and among SPCs, it was 5.8% (3.3%–8.2%). For TPCs, compared to matched patients, the age-adjusted hazard ratio (95% CI) for death was 3.0 (1.39–6.50). The 10-year cumulative mortality of TPCs and matched patients was 75.7% and 42.0%, respectively.

Conclusions

In Northern Portugal, TPCs occurred mainly in digestive organs, followed by the breast and urinary tract, with a 10-year cumulative incidence of 0.5% among all FPCs. TPCs had a worse long-term survival compared to patients with an SPC only.