Lancet: US finds link between endometrial thickness & cancer
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| Transvaginal ultrasound uses high-frequency sound waves to provide images of structures in the body, such as the uterus, fibroids, ovaries and other organs. Image source: University of North Carolina at Chapel Hill School of Medicine |
With an incidence of approximately 18 cases per 100,000 women in the U.K., endometrial cancer is the most common gynecological cancer in Europe, with rates increasing by more than 30 percent between 1993 and 2005. Nevertheless, "[i]n the general population, there has been limited enthusiasm to explore the usefulness of screening for endometrial cancer because patients have a good prognosis relative to other cancers," according to Ian Jacobs, MD, of the department of gynecological oncology at University College, London's EGA Institute for Women's Health in London, and colleagues.
Currently, only women diagnosed with Lynch Syndrome undergo routine screening for endometrial cancer. "However, in view of the rising incidence of endometrial cancer, coupled with increasing life expectancy, there is now a need to revisit screening. Additional factors are mortality greater than 30 percent within 10 years of diagnosis and a proven link between stage and survival raising the possibility of a mortality benefit from earlier detection," Jacobs and co-authors argued.
Jacobs and colleagues pulled information from the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS), which originally screened 48,230 post-menopausal women for ovarian cancer at 13 institutions across the U.K. Jacobs and colleagues primarily examined the relationship between endometrial thickness and the incidence of endometrial cancer, while also considering other demographic and physiological risk factors among 37,038 eligible, post-menopausal women from the UKCTOCS study.
One hundred thirty-six women were diagnosed with endometrial cancer or atypical endometrial hyperplasia (AEH) within one year of a transvaginal ultrasound (TVS) screening. Of these 136 cases, 96 were asymptomatic (with the primary symptom being vaginal bleeding) and had available endometrial measurements.
The authors found a significant difference in endometrial thickness between patients diagnosed with endometrial cancer and the controls, with median caliper measurements of endometrial thickness at 11.0 mm in cancer patients and 2.9 mm in cancer-free women.
Jacobs and co-authors also found that increasing weight and older age were associated with higher risks of endometrial cancer, while use of the oral contraceptive pill, age at menarche and pregnancies of longer than six months were associated with decreased risk. A history of breast cancer was also correlated with endometrial cancer, although the authors hypothesized that this was the result of those women taking tamoxifen.
Running a logistic regression of these risk factors in relation to area under the receiver operator curve (ROC) for endometrial thickness, Jacobs and colleagues computed an optimal cutoff value of 5.15 mm for symptomatic women (4.5 for asymptomatic individuals). This value produced a sensitivity of 80.5 percent and a specificity of 86.2 percent for endometrial cancer or AEH.
The authors constructed several other cutoff values, noting that the "burden of diagnostic procedures and false-positive results can be reduced by limiting screening to a higher-risk group." For instance, limiting screening to the 25 percent of the sample with the highest risks, meaning women with associated characteristics and endometrial thicknesses greater than 6.75 mm, yielded a sensitivity of 84.3 percent and a specificity of 89.9 percent.
"Our findings confirm the strong correlation between TVS findings and subsequent diagnosis of endometrial cancer," the authors explained. Jacobs and colleagues did acknowledge that bias in measuring symptoms may have been introduced by some sonographers that more consistently documented vaginal bleeding only in women with greater endometrial thickness.
The authors did not advocate outright TVS screening of women for endometrial cancer. Given the disease's low incidence, Jacobs and colleagues considered it "extremely difficult" to establish clear statistical effects of TVS screening on reducing endometrial mortality, with studies requiring hundreds of thousands of individuals.
"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 authors concluded.