Incidence and predictors of peritoneal metastases of gynecological origin: a population-based study in the Netherlands

Objective: Peritoneal metastases (PM) are a challenge in gynecological cancers, but its appearance has never been described in a population-based study. Therefore, we describe the incidence of PM and identify predictors that increase the probability of peritoneal spread. Methods: All ovarian, endometrial and cervical cancer patients diagnosed in the Netherlands between 1989 and 2015 were identified from the Netherlands Cancer Registry and stratified for PM. Crude and age-adjusted incidence over time was calculated. Independent predictors for PM were identified using uni- and multivariable analyses. Results: The 94,981 patients were diagnosed with ovarian, endometrial or cervical cancer and respectively 61%, 2% and 1% presented with PM. Predictors for PM in ovarian cancer were: age between 50 and 74 years (odds ratio [OR]=1.19; 95% confidence interval [CI]=1.08-1.32), other distant metastases (OR=1.25; 95% CI=1.10-1.41), poor differentiation grade (OR=2.00; 95% CI=1.73-2.32) and serous histology. Predictors in endometrial cancer were lymph node metastases (OR=2.32; 95% CI=1.65-3.26), other distant metastases (OR=1.38; 95% CI=1.08-1.77), high-grade tumors (OR=1.95; 95% CI=1.38-2.76) and clear cell (OR=1.49; 95% CI=1.04-2.13) or serous histology (OR=2.71; 95% CI=2.15-3.42). In cervical cancer, the risk is higher in adenocarcinoma than in squamous cell carcinoma (OR=4.92; 95% CI=3.11-7.79). Conclusion: PM are frequently seen in patients with ovarian cancer. In endometrial and cervical cancer PM are rare. Histological subtype was the strongest predictive factor for PM in all 3 cancers. Better understanding of predictive factors for PM and thus the biological behavior is of paramount importance.