Transvaginal ultrasound screening can pick up most cases of endometrial cancer in postmenopausal women before symptoms appear, researchers reported.
Such testing could identify more than 80% of cases but would have a false-positive rate of nearly 15%, according to Ian Jacobs, MD, of University College London, and colleagues.
The sensitivity and specificity could be improved if the ultrasound screening was restricted to a high-risk population, Jacobs and colleagues reported online in The Lancet Oncology.
On the other hand, many experts argued that the method is unlikely to be cost-effective.
"It's still a very crude screening test and nonspecific," said William Cliby, MD, of the Mayo Clinic in Rochester, Minn. He noted in an e-mail to MedPage Today and ABC News that even a 3% false-positive rate would translate into 3,000 unnecessary tests if 100,000 women were screened.
And "it's highly unlikely to be cost-effective," argued Jonathan Berek, MD, of Stanford University School of Medicine in Stanford, Calif.
Almost all women with endometrial cancer will develop symptoms -- typically vaginal bleeding -- before the cancer begins to spread, he said in an e-mail. At that point, an endometrial biopsy will be used to make the diagnosis, he said.
Endometrial cancer, Jacobs and colleagues wrote, is the most common gynecological cancer, and it usually has a good prognosis. But for that reason, there is little information on the role of screening in women without symptoms, the researchers noted.
The issue needs to be revisited, they argued, because increasing obesity and falling fertility "suggest that incidence of endometrial cancer will continue to rise in postmenopausal women and will become a substantial public health problem worldwide."
To examine the topic, Jacobs and colleagues conducted a nested case-control study within the United Kingdom Collaborative Trial of Ovarian Cancer Screening. As part of the trial, transvaginal ultrasound was performed on 48,230 women, but more than 11,000 were ineligible for this analysis either because they had had a hysterectomy or they did not have endometrial thickness recorded, leaving a cohort of 37,038 women.
Of those, the researchers found, 136 women developed endometrial cancer or atypical endometrial hyperplasia within a year of their ultrasound. The median follow-up was 5.11 years.
Of those women, Jacobs and colleagues found, 81% had an endometrial thickness of at least five millimeters, while 83% of those without disease had a thickness of less than five millimeters.
At the optimum cutoff for endometrial thickness of 5.15 millimeters, the transvaginal ultrasound would detect 80.5% of cancer cases and would falsely indicate that a healthy woman had cancer 13.8% of the time, Jacobs and colleagues found.
The false-positive rate could be lowered by increasing the thickness cutoff, they found, but in that case fewer cancers would be detected.
A logistic regression model -- including factors such as weight, age, cancer history and use of contraceptive pills -- found that 39.5% of the cases would fall in the 25% of the population that was identified as being at high risk.
If screening were restricted to those women, Jacobs and colleagues reported, the sensitivity and specificity were 84.3% and 89.9%, respectively, if the thickness cutoff were set at 6.75 millimeters.
"A targeted screening approach might help reduce the overall number of false-positive findings while maintaining a high sensitivity," they argued.
The study "provides very important information" on screening for endometrial cancer and is probably the largest such study to date, commented Ignace Vergote, MD, PhD, and colleagues from University Hospitals Leuven in Leuven, Belgium.
On the other hand, it falls short of proving "a benefit for screening for endometrial cancer because of an absence of survival data," Vergote and colleagues argued in an accompanying comment article.
According to Diane Harper, MD, of the University of Missouri, "The test characteristics are not good enough" and the ultrasound process may be less acceptable to many women than a biopsy, which is more accurate in the first place.
"Having a transvaginal probe inserted and moved around is quite invasive for the patient," Harper said in an e-mail. On the other hand, while an endometrial biopsy can cause painful cramping, it's relatively quick and involves only the woman and her doctor, she argued.
"This investigation will not change clinical practice," said Sean Dowdy, MD, also of the Mayo Clinic in Rochester. The procedure has been used for many years in patients with postmenopausal bleeding, he noted in an e-mail, "but both sensitivity and specificity are far too low" for it to be used as a screening method.
Endometrial cancer is usually diagnosed early because of the vaginal bleeding experienced by most patients, so "there is far less to gain" from a screening test for this disease, Dowdy wrote, adding that a more effective intervention would be reducing obesity among women.
This article was developed in collaboration with ABC News.
The study had support from Cancer Research UK, the Medical Research Council, NHS Research and Development, and The Eve Appeal. Jacobs reported financial links with Becton Dickinson and Abcodia.
The comment authors said they had no potential conflicts.
Zalman S. Agus, MD Emeritus Professor
University of Pennsylvania School of Medicine and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
The Lancet OncologySource Reference: Jacobs I, et al "Sensitivity of transvaginal ultrasound screening for endometrial cancer in postmenopausal women: a case-control study within the UKCTOCS cohort" Lancet Oncol 2010; DOI: 10.1016/S1470-2045(10)70268-0.
The Lancet OncologySource Reference: Vergote I, et al "Should we screen for endometrial cancer?" Lancet Oncol 2010; DOI: 10.1016/S1470-2045(10)70280-1.