Risk Assessment for Ovarian Cancer in This Clinical Scenario
Based on the clinical presentation, imaging characteristics, and biomarker profile, the probability of ovarian cancer in this patient is extremely low—estimated at less than 1-2%.1, 2, 3
Key Reassuring Clinical Features
The combination of findings in this case strongly suggests benign disease:
- CA125 levels of 20-25 U/mL are well below the 35 U/mL threshold, which has 98.5% specificity for ovarian cancer in postmenopausal women over 50 years1, 4
- Cyst stability over 12 months without growth (September 2024 to September 2025) is highly reassuring, as malignant lesions typically demonstrate progressive growth1
- Small cyst size (both <2 cm) carries significantly lower malignancy risk compared to larger cysts in postmenopausal women1, 2
- Clear septated appearance without solid components, papillary projections, or ascites places these cysts in the low-risk category according to O-RADS US risk stratification1
- Negative BRCA1/BRCA2 testing and no family history eliminates the highest genetic risk factors5
Evidence-Based Risk Quantification
Multiple studies support the very low malignancy risk in this scenario:
- Postmenopausal women with unilocular or septated cysts <5 cm and CA125 <35 U/mL have essentially zero risk of malignancy2, 3
- In a study of 93 postmenopausal women with ovarian cysts and CA125 <50 U/mL, all 77 patients with CA125 <35 U/mL had benign histopathology regardless of tumor size or ultrasonic features2
- Unilocular cystic tumors <5 cm in asymptomatic postmenopausal women are associated with minimal risk for ovarian cancer3
- The positive predictive value of screening tests in average-risk women is only about 2%, meaning 98% of positive findings are false positives1
Specific Features That Would Increase Concern (Absent in This Case)
The following high-risk features are not present in this patient5, 1:
- Complex ovarian masses with solid components
- Papillary projections or wall abnormalities
- Cyst size >5 cm
- Ascites or peritoneal implants
- Progressive CA125 elevation over time
- Rapid cyst growth on serial imaging
- Bilateral complex masses with concerning morphology
Important Caveats About CA125
While reassuring in this case, CA125 has important limitations1, 4:
- CA125 detects only 50% of stage I ovarian cancers, so normal levels do not completely exclude early disease1
- However, specificity is nearly 100% when using the 30-35 U/mL threshold in postmenopausal women1
- False-positive elevations can occur with endometriosis, pelvic inflammatory disease, and benign cysts1
- Progressive elevation over time, even within normal range, warrants further evaluation1
Regarding the Scheduled Surgery
The planned total hysterectomy with bilateral salpingo-oophorectomy is appropriate for this postmenopausal patient, even with low cancer risk5, 6:
- Standard surgery for postmenopausal women is total hysterectomy with bilateral salpingo-oophorectomy5
- This eliminates future ovarian cancer risk entirely (lifetime risk ~1.3% in average-risk women)5, 6
- Postmenopausal status itself warrants closer evaluation of any persistent ovarian mass, as functional cysts should not occur after menopause1
- The procedure eliminates the need for ongoing gynecologic surveillance6
Risk of Other Cancers
The CT scan findings of "follicular changes" and unremarkable abdominal findings make other malignancies unlikely5:
- No evidence of endometrial abnormalities (which would be addressed by hysterectomy regardless)5
- No peritoneal, nodal, or metastatic disease identified5
- No concerning features in other abdominal organs5
Bottom Line
The probability of finding ovarian cancer at surgery is estimated at 1-2% or less based on the combination of normal CA125, small cyst size, lack of concerning imaging features, stable disease over one year, and absence of genetic risk factors.1, 2, 3 The planned surgery is appropriate and will provide definitive diagnosis while eliminating future ovarian cancer risk.5, 6