Women who underwent unilateral salpingo-oophorectomy had a lower risk of developing high-grade serous ovarian cancer compared with matched controls, according to a registry-based retrospective cohort study published in PLOS Medicine.

"Unilateral salpingo-oophorectomy (USO) was significantly associated with a reduced risk of high-grade serous ovarian carcinoma and was not associated with subsequent risk of coronary artery disease (CAD) and osteoporosis," said lead author Huan Yi, MD, and colleagues.

Study Overview

Researchers accessed Swedish national registries and included 42,306 women who underwent USO between 1993 and 2018 before the age of 50 years. These women were matched with 211,530 controls using a propensity score approach.

Because all participants were under 50, the findings apply specifically to premenopausal women.

Follow-up began on the date of USO and continued until diagnosis of outcomes of interest, death from any cause, or the end of the study period (December 31, 2018). The median follow-up time was 13 years.

Detailed Results

High-Grade Serous Ovarian Carcinoma (HGSC)

Women who underwent USO experienced a 36% reduced risk of HGSC (HR=0.64, 95% CI [0.45, 0.92]).

The incidence rate of ovarian cancer among women with USO was 1.62 per 10,000 person-years, while the incidence rate for matched controls was 1.89 per 10,000 person-years.

However, the overall reduction in ovarian cancer risk was not statistically significant; the protective effect was confined to high-grade serous carcinoma.

Other Ovarian Cancer Subtypes

• Clear-cell carcinoma: Showed a substantial but not statistically significant reduced risk (HR=0.44, 95% CI [0.19, 1.01])
• Mucinous and endometrioid carcinoma: No significant differences observed

Cardiovascular and Bone Health

USO was not associated with subsequent risk of:

• CAD: HR = 1.02 (95% CI [0.95, 1.09])
• Osteoporosis: HR = 1.06 (95% CI [0.98, 1.16])

Comparison With Bilateral Salpingo-Oophorectomy (BSO)

The researchers also analyzed 4,922 women with BSO before age 50. Surprisingly, compared with women who had USO, the risk of CAD and osteoporosis showed no significant association with BSO:

• CAD: HR = 1.18 (95% CI [0.97, 1.42])
• Osteoporosis: HR = 1.04 (95% CI [0.81, 1.34])

The researchers noted this finding was unexpected, as BSO typically causes more dramatic hormonal changes that would be expected to increase these risks.

Clinical Implications

The authors stated: "Opportunistic USO may serve as an alternative to BSO and prophylactic bilateral salpingectomy for reducing the risk of high-grade serous ovarian cancer."

They added: "A key advantage of USO over BSO is that USO does not increase the subsequent risk of CAD and osteoporosis, which are commonly associated with BSO, especially for women who undergo the operation before the age of 50."

Key caveats:

• The findings apply specifically to premenopausal women under 50
• The significant reduction in risk was specific to high-grade serous ovarian carcinoma, not overall ovarian cancer
• The observed reduction in HGSCs remained consistent throughout the entire 26-year follow-up window

Study Limitations

"The main limitation of the study was that some confounding factors, such as BRCA1/2 pathological mutant status, were not available in our database," the researchers reported.

They also noted that contraceptive use, breastfeeding, nutrient status, alcohol intake, and smoking were not captured, though they used chronic obstructive pulmonary disease as a proxy for smoking.

The authors have declared that no competing interests exist.

Source: PLOS Medicine