Incidental Serous Tubal Intraepithelial Carcinoma Finding in a Nepalese Patient Undergoing Opportunistic Salpingectomy and the Discovery of a BRCA1 Pathogenic Variant.

Abstract

Background: Serous tubal intraepithelial carcinoma (STIC) lesions are the precursor to high grade serous ovarian carcinomas (HGSC) which have the highest mortality rate among gynecologic malignancies. Among women diagnosed with HGSC, 20% are found to be secondary to hereditary causes with the majority being associated with germline pathogenic variants (PVs) in BRCA1 and BRCA2 genes. Patients with a PV are high risk for developing HGSC, so it is recommended that they undergo risk reducing salpingo-oophorectomies in their 30s-40s. Opportunistic salpingectomy is the only ovarian cancer prevention method available for average risk patients. While STIC lesions are rare in average risk women, studies quote incidental STIC lesion findings in 1-7% of patients undergoing opportunistic salpingectomy.

Case: A 38-year-old woman (gravida 2, para 2) of Nepalese ethnicity had an incidental finding of a STIC lesion at the time of opportunistic salpingectomy for permanent sterilization at cesarean delivery. The STIC lesion was found using representative sampling of the fallopian tubes since the patient was considered average risk for ovarian cancer. This method is much less sensitive than SEE-FIM protocol which is used with known high-risk women. This ultimately led to discovery of a BRCA1 mutation in the patient.

Conclusion: SEE-FIM protocol is used to identify STIC lesions, but it is not routinely used on average risk patients' fallopian tubes. Using SEE-FIM protocol would lead to less missed STICs, but it is unclear how much extra cost and effort would be required to implement this. There are knowledge gaps when it comes to understudied populations and hereditary breast and ovarian cancer (HBOC) gene prevalence. Studies show that current BRCA prediction models underestimate HBOC gene prevalence in Asian populations. Diagnosing STICs in understudied populations could lead to the discovery of an HBOC PV which the patient may not have discovered until after a cancer diagnosis. Identification of a STIC in an average risk patient should lead to a referral for genetic counseling and screening.