Histology-specific long-term oncologic outcomes in patients with epithelial ovarian cancer who underwent complete tumor resection: The implication of occult seeds after initial surgery.

Objective: Assessing the histology-specific prognosis of epithelial ovarian cancer (OvCa) is clinically challenging, especially in a patient population with a favorable prognosis. This study investigated the histology-specific long-term oncologic outcomes in OvCa patients who underwent complete tumor resection using a large-scale patient cohort form multiple institutions under a central pathological review system.

Methods: A regional multi-institutional study was conducted from 1986 to 2019. Of the 4,898 patients with ovarian tumors enrolled, 1,175 patients who underwent complete tumor resection were classified into three classes based on clinically important prognostic factors: stage, cytology, ascites volume. For each class category, the effect of histology types on recurrence-free survival, the site of recurrence, and post-recurrence survival was evaluated.

Results: Recurrence-free survival varied significantly across different histologies (P < 0.001). The risk of recurrence was higher in serous carcinoma compare to other histologies (P < 0.001). The site of tumor recurrence varied by the histology type. Multinominal logistic regression analysis revealed that mucinous histology had a significantly higher likelihood of developing recurrent tumors at distant sites from the peritoneum compared to other histologies (P = 0.002). Conversely, serous histology was associated with better post-recurrence survival (Log-rank P < 0.001).

Conclusions: Long-term oncologic outcomes significantly differ by histology type in OvCa patients who have undergone complete tumor resection at the initial surgery. A careful evaluation of the clinical background is necessary for these patients, and further clinical research into individualized treatment approaches is essential.