What is the likelihood that a thickened endometrium (endometrial lining) post-menopause is endometrial cancer?

Risk of Endometrial Cancer in Postmenopausal Women with Thickened Endometrium

The risk of endometrial cancer in postmenopausal women with thickened endometrium varies from 3.17% to 9.1%, with higher risk when endometrial thickness exceeds 10-11mm. 1, 2

Diagnostic Approach for Postmenopausal Women with Thickened Endometrium

Endometrial Thickness Cutoffs

• An endometrial thickness ≤4mm has a negative predictive value for endometrial cancer of nearly 100% in postmenopausal women 3
• Endometrial thickness >4mm requires further evaluation with endometrial sampling 3
• Risk of malignancy increases significantly with endometrial thickness ≥10mm:
  • 6.3% prevalence of endometrial malignancy with ET ≥10mm 2
  • 9.1% risk estimate for endometrial cancer with ET >11mm 1

Diagnostic Algorithm

1. Initial Assessment with Transvaginal Ultrasound (TVUS):

   • TVUS should be combined with transabdominal ultrasound for anatomic overview
   • Color and spectral Doppler should be used to assess vascularity 3
   • Note: Absence of vascularity on Doppler does not rule out pathology 3

2. Tissue Sampling Based on Endometrial Thickness:

   • ET ≤4mm: No further evaluation needed if asymptomatic 4, 3
   • ET >4mm to <10mm: Consider endometrial sampling, especially with risk factors 3
   • ET ≥10mm: Histopathological testing strongly recommended 2

3. Tissue Sampling Methods:

   • Office endometrial biopsy as first-line sampling (note: 10% false-negative rate) 3
   • Hysteroscopy with directed biopsy for ET ≥8mm 3
   • If initial biopsy shows limited benign surface endometrium, consider repeat sampling as this may indicate insufficient sampling 5
   • Negative endometrial biopsy in a symptomatic patient must be followed by fractional D&C under anesthesia 3

Risk Factors That Increase Concern with Thickened Endometrium

• Postmenopausal bleeding (present in 90% of endometrial cancer cases) 3
• Obesity (higher BMI associated with increased risk of atypia or malignancy) 5
• Diabetes mellitus
• Hypertension
• History of unopposed estrogen exposure
• Tamoxifen therapy 3
• Lynch syndrome (particularly MLH1 gene mutation) 3

Diagnostic Performance of Hysteroscopy

• For normal findings: Sensitivity 100%, Specificity 98.6%, PPV 95.2%, NPV 100% 6
• For endometrial cancer: Sensitivity 100%, Specificity 99.6%, PPV 75%, NPV 100% 6
• For endometrial hyperplasia: Sensitivity 66.7%, Specificity 100%, PPV 100%, NPV 98.1% 6

Common Pitfalls and Caveats

• Initial limited benign surface endometrial sample may represent insufficient sampling and should not be considered definitive 5
• Sonohysterography cannot reliably distinguish between benign pathology and endometrial cancer 3
• Among postmenopausal women with thickened endometrium but no bleeding, the incidence of endometrial cancer is relatively low (3.17%) but still warrants evaluation 1
• Asymptomatic women with risk factors for endometrial cancer who have endometrial thickening and other positive findings on ultrasound (increased vascularity, inhomogeneity, particulate fluid, thickness >11mm) should be managed on a case-by-case basis 4

By following this systematic approach to evaluating postmenopausal women with thickened endometrium, clinicians can appropriately identify those at higher risk of endometrial cancer and ensure timely diagnosis and treatment.