A nationwide study of ovarian serous borderline tumors in Denmark 1978–2002. Risk of recurrence, and development of ovarian serous carcinoma

Objective Absolute risk and risk factors for recurrence and ovarian serous carcinoma following ovarian serous borderline tumors (SBTs) is not well-established. Methods We included all women with SBTs in Denmark, 1978–2002. Diagnoses were confirmed by centralized pathology review and classified as atypical proliferative serous tumor (APST) or noninvasive low-grade serous carcinoma (LGSC). Implants were classified as noninvasive or invasive. Medical records were collected and reviewed, and follow-up was obtained. Subsequent diagnoses were also confirmed by centralized pathology review. We examined absolute risk and risk factors for recurrent APST and serous carcinoma using Cox regression. Results The absolute serous carcinoma risk after, respectively, 5 and 20 years was 5.0% and 13.9% for noninvasive LGSC, and 0.9% and 3.7% for APST. Serous carcinoma risk was significantly higher following noninvasive LGSC compared with APST among stage I patients/patients without implants (HR = 5.3; 95% CI: 1.7–16.3), whereas no significant association with tumor type was found in advanced stage patients/patients with implants. Advanced stage – notably invasive implants – bilaterality, surface involvement, and residual disease increased serous carcinoma risk. However, women with stage I APST also had a higher risk than the general population. Conclusions This largest population-based cohort of verified SBTs revealed that women with noninvasive LGSC are significantly more likely to develop serous carcinoma than women with APST, which could not entirely be explained by invasive implants. Although invasive implants was a strong risk factor for serous carcinoma, even women with stage I APST were at increased risk compared with the general population.