Surveillance for endometrial cancer with transvaginal ultrasonography of breast cancer patients under tamoxifen treatment

The association of endometrial thickness with the risk of developing endometrial cancer (EC) within 2 years was investigated in a consecutive cohort of 1205 breast cancer patients under tamoxifen treatment, undergoing transvaginal ultrasonography (TVUS) for follow-up purpose (asymptomatic, 1068) or for abnormal uterine bleeding (AUB, 137). Linkage with tumour registry allowed for the follow-up of 3184.3 person-years. According to underlying incidence, 1.85 EC cases were expected in the study cohort while 12 were observed (observed/expected ratio=6.49, 95% CI 3.35–11.33; asymptomatic=4.09, 95% CI 1.65–8.43, symptomatic=35.71, 95% CI 11.59–83.34). No EC was observed with thickness (half layer) <3 mm. Raising this threshold increased specificity with a substantial loss of sensitivity (⩾3, ⩾4, ⩾6, ⩾9 mm; spec.=25.8, 44.5, 76.1, 91.5%, sens.=100, 91.6, 75.0, 66.6%). The presence of AUB was rather specific (88.94%) but poorly sensitive (41.67%). A combination of AUB presence/absence and thickness allowed the best accuracy (AUB + thickness ⩾3, ⩾4 or ⩾5; sens.=100, 81.6 or 91.6%; spec.=22.8, 40.4, or 56.7%). Breast cancer patients under tamoxifen might be selected for further invasive assessment on the basis of AUB and endometrial thickness assessed at TVUS.