Large cohort supports ultrasound for endometrial cancer scans

Transvaginal ultrasound demonstrates good sensitivity and specificity for detecting endometrial cancer, a study from the University College, London. finds. But that doesn’t mean it’s suited for use in the general population just yet. The researchers found transvaginal ultrasound is better for high-risk groups prone to endometrial cancer, and especially in the management of postmenopausal women undergoing pelvic scans for reasons other than vaginal bleeding.

Endometrial cancer is the most common gynecological cancer in Europe, and has an increasing incidence in postmenopausal women in many northern and western European countries. In the U.K., overall incidence of endometrial cancer jumped from 13.5 per 100,000 in 1993 to 17.9 per 100,000 in 2005. The increase in obesity and the fall in fertility rates, two risk factors for endometrial cancer, suggest the incidence of endometrial cancer will continue to rise in postmenopausal women and will become a substantial public health problem worldwide, the authors said.

For asymptomatic women, there is currently no screening test to detect early stage endometrial cancer. For symptomatic women, transvaginal ultrasound (TVS) and endometrial sampling are used to assess the endometrium. Thicker endometria are associated with endometrial cancer.

Ian Jacobs, from the Gynecological Oncology department at University College London, and colleagues conducted a nested case-control study of postmenopausal women who underwent TVS in the Collaborative Trial of Ovarian Cancer Screening, which included 37,038 women.

Using an endometrial thickness cutoff of 5.15mm, TVS has an 80.5% sensitivity and an 86.2% specificity. Using this threshold, if the entire population was screened, one case of endometrial cancer would be detected for every 47.7 women screened (Lancet doi:10.1016/S1470-2045(10)70268-0 ).

Using an endometrial thickness cutoff of 10 mm or greater, TVS has a 54.1% sensitivity and a 97.2% specificity.

When the analysis was restricted to the 96 asymptomatic women who developed endometrial cancer, or atypical endometrial hyperplasia, during the follow-up period, an endometrial thickness cutoff of 5 mm achieved a sensitivity of 77.1% and specificity of 85.8%. In the high-risk population, an endometrial thickness cutoff 6.75 mm achieved sensitivity of 84.3% and specificity of 89.9%.

“Although the role of population screening for endometrial cancer remains uncertain, the findings are of immediate value in the management of increased endometrial thickness in postmenopausal women undergoing pelvic scans for reasons other than vaginal bleeding,” the researchers said.

A study like this lets physicians use TVS to triage the incidental findings in asymptomatic patients as opposed to using it as a pure screening mechanism, said Dr. Michael Blumenfeld, an associate professor in the ob/gyn department at Ohio State University Medical Center and the clinical director of the center for women’s health.

“To be a screening test TVS has to affect and improve survival,” he said. “There is no evidence from a prospective study that it’s going to change the long-term outcome.”

There’s a concern if physicians performed TVS on every single patient, including those at low risk, more harm than good would be done due to unnecessary procedures, he said.

For radiologists, the study will provide more information on what they find, he said. In all likelihood, TVS will end up being a part of the pelvic exam, Blumenfeld said.

“If a doctor scans for reasons such as an ovarian mass, and then finds an endometrial thickness, he or she needs to know how to triage the patient,” he said. “This study helps with that.”

This study forms the basis for further research, Jacobs said. In particular, issues of early detection, morbidity, acceptability, and health economics of intervening on the basis of endometrial thickness will need to be the subject of future studies.