Frequency of serous tubal intraepithelial carcinoma (STIC) in patients with high grade serous ovarian cancer.

OBJECTIVE: Serous tubal intraepithelial carcinoma (STIC) is a known precursor of high-grade serous ovarian cancer (HGSOC). This study aimed to evaluate the proportion of STIC in patients with HGSOC and analyze the STIC-related prognosis in patients with HGSOC.

MATERIALS AND METHODS: All pathology reports at our institution that included bilateral salpingectomies of patients with HGSOC from January 2013 to December 2018 were reviewed by two experienced pathologists. The specimens from the ovaries and the salpinx including fimbria were examined. We analyzed the correlation between STIC and HGSOC and compared the clinical characteristics and STIC-related prognostic outcomes in patients with HGSOC.

RESULTS: Eleven of the 76 cases were STIC. BRCA mutations were found in 16.9% of patients with HGSOC. STIC was observed in 30.0% of patients with BRCA mutations and in 14.3% of patients without BRCA mutations. The incidence of STIC in patients with BRCA mutations was approximately twice that in patients without BRCA mutations; however, the difference was not statistically significant (P = 0.231). Further, the 5-year survival rate of patients without STIC appeared to be high; nevertheless, the difference was not statistically significant (59.7% vs. 47.4%, P = 0.633). Moreover, there was no significant difference in disease-free survival rate according to STIC (36.4% vs. 33.1%, P = 0.956).

CONCLUSION: STIC was identified in patients with HGSOC, and STIC incidence was prominent in HGSOC related to BRCA mutation. Although low frequency, STIC was detected in patients without BRCA mutation. Therefore, prophylactic salpingectomy may be useful for prevention of HGSOC.