Introduction Current literature suggests that in patients with radiologic findings of a pelvic mass and possible carcinomatosis, a preoperative serum CA-125/carcinoembryonic antigen (CEA) ratio ≥25 is strongly suggestive of primary epithelial ovarian carcinoma vs benign disease and other primary malignancies. However, no recent study has specifically addressed the accuracy of this ratio. Our study aimed to examine the utility of this ratio in patients who undergo primary debulking surgery (PDS).

Methods We performed a retrospective review of patients who underwent surgery for presumed advanced ovarian cancer between 1/2015 and 11/2022. Tumor marker levels obtained closest to the day of PDS were analyzed. Preoperative CA-125/CEA ratios were calculated and compared to surgical pathology results. Patients with normal marker levels were excluded.

Results Of the 443 patients who had preoperative CA-125 and CEA results available, 381 (86%) had a ratio ≥25. Of these 381 patients, 380 (99.7%) had epithelial ovarian cancer and 1 (0.3%) had colon cancer. Sixty-two (14%) of the 443 patients had a ratio <25, of whom 55 (89%) had ovarian cancer (1 with small cell ovarian cancer) and 7 (11%) did not have final surgical pathology consistent with ovarian cancer.

Conclusion/Implications A CA-125/CEA ratio ≥25 is highly predictive of epithelial ovarian carcinoma, with our study showing a positive predictive value of 99.7%. A ratio <25 in patients with presumed ovarian cancer was associated with a non-gynecologic malignancy in 1 of 10 patients. The CA-125/CEA ratio provides useful preoperative information in the diagnosis and management of patients with possible advanced ovarian cancer.