Background: Secondary malignant involvement of the ovaries, designated here as secondary ovarian malignancy (SOM), arises from a wide array of extraovarian tumour sources, and both its frequency and the distribution of primary sites differ substantially across geographic regions and institutional types. This report characterizes the pathological findings and oncological outcomes of consecutive patients with histologically confirmed SOM who were managed surgically at a high-volume gynaecologic oncology unit.

Methods: Records of 806 women who underwent surgery for a suspected pelvic mass or ovarian neoplasm (2012-2016) were retrospectively analysed; 488 met the inclusion criteria for a definitive ovarian cancer diagnosis. Actuarial survival estimates were generated using the Kaplan-Meier method, and intergroup comparisons were performed using the log-rank test.

Results: Secondary ovarian tumours were identified in 79 women (16.2%), ranking second in frequency, only behind primary epithelial ovarian cancer. Non-gynecological primary sites accounted for 65.8% (n=52) of cases; endometrial (34.2%), colorectal (22.7%), and gastric (20.2%) carcinomas were the three most prevalent sources. Concurrent bilateral adnexal involvement was documented in 62% of cases, with a mean tumour diameter of 6.47 cm. Patients whose primary tumour was of a gynaecological origin were considerably older (62.3 vs. 52.8 years; p=0.007), suffered higher disease-related mortality (59.3% vs. 34.6%; p=0.036), and had a markedly abbreviated median survival (10.0 vs. 32.6 months; p=0.05) relative to those with non-gynaecological sources. Colorectal (46.4 months) and breast (45.0 months) primaries yielded the most favourable survival durations. Surgical extent and adjuvant treatment modality had no statistically significant bearing on outcomes.

Conclusions: Secondary ovarian malignancy is a clinically significant entity, accounting for nearly one in six of all ovarian cancers in this cohort. Prognosis is generally poor but varies considerably depending on the originating tumour. Determining the primary site with precision is foundational to appropriately selecting a surgical strategy and individualised systemic therapy.