Ovarian squamous cell carcinoma: clinicopathological features, prognosis and immunotherapy outcomes.

Objective: To explore the characteristics and survival outcomes of ovarian squamous cell carcinoma (SCC) and the treatment effectiveness of immune checkpoint inhibitors (ICIs).

Methods: Patients diagnosed with ovarian SCC at Peking Union Medical College Hospital between January 2000 and September 2023 were included. Overall survival (OS) and progression-free survival (PFS) were analyzed using the Kaplan-Meier method. Univariate and multivariate analysis of OS were performed using the Cox proportional hazards model.

Results: A total of 42 patients were included, with a median age of 51.5 years (range, 23-74). The majority had SCC arising from teratomas (54.8%), followed by endometriosis (14.3%) and Brenner's tumor (2.4%). Patients undergoing molecular testing exhibited a median tumor mutation burden (TMB) of 10.00 mutations/Mb (range, 7.28-46.86), predominantly featuring mutations. Thirty-eight patients (90.5%) received adjuvant chemotherapy. The median OS was 42.0 months, with the 1- and 5-year OS rates were 73.7% and 48.7%, respectively. And the median PFS was 26.9 months, with the 1- and 5-year PFS rates were 57.5% and 43.8%, respectively. Five patients underwent first-line postoperative adjuvant therapy combining ICIs with chemotherapy. During the 9.5 to 25.1 months follow-up, 4 patients showed no evidence of disease, while 1 relapsed and received treatment. Late-stage disease and younger age at diagnosis were associated with worse survival outcomes.

Conclusion: The prognosis for ovarian SCC remains unfavorable. The stage and age were prognostic predictors for survival. ICIs may be beneficial for patients with ovarian SCC, particularly those with a high TMB.