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Tamoxifen, an anti-estrogen drug, is taken by a great number of women as treatment for breast cancer, or as a preventative measure against the development of breast cancer. Although Tamoxifen is attributed to improving survival in a large percentage of breast cancer patients, its long-term use has shown to have an increased risk (two tenths of one percent) in the development of uterine cancer.

Since uterine cancer has a high cure rate when caught in its early stages, researchers have been trying to develop an accurate and effective screening method for early detection. Abnormal vaginal bleeding is the most common symptom of uterine cancer and occurs in most women who develop this disease.

Endometrial biopsies, the removal of a small piece of tissue from the lining of the uterus, and transvaginal ultrasonography, an ultrasound of the uterus, are two procedures that have been evaluated in the screening for uterine cancer. However, these procedures are associated with many false positive results. A false positive test result occurs when the diagnostic procedure suggests cancer is present when it actually does not exist. A false positive reading leads to unnecessary invasive procedures that carry risks such as uterine perforation, pain, infection, anxiety, cost, unnecessary hysterectomies and inconvenience. In order to prevent these negative effects that can be associated with invasive procedures, it is important to develop reliable and accurate screening methods.

In the Journal of Clinical Oncology, results from two clinical trials evaluating the accurateness of endometrial biopsies and vaginal ultrasonographies in screening for uterine cancer were recently published. The first study involved a group of over 110 women who were largely asymptomatic (no abnormal vaginal bleeding). These women received endometrial biopsies over a 5-year period. Over 12% of these women underwent unnecessary surgical procedures due to false positive results from their biopsies. None of these women were found to have uterine cancer.

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The second study involved a group of almost 250 women taking Tamoxifen who were largely asymptomatic for uterine cancer. These women received routine transvaginal ultrasonographies, totaling over 1,260 procedures, as a screening method for early detection of uterine cancer. Over one fifth of these women underwent further invasive procedures, including a hysterectomy, due to false positive results from ultrasonography. Out of 1,260 procedures, only one woman was found to have uterine cancer. This is a detection rate of less than one tenth of one percent.

It is extremely important for women who are taking Tamoxifen to have annual gynecological check-ups, and to report any abnormal vaginal bleeding to their physician immediately. However, results from these two studies, which are consistent with previous clinical studies, indicate that routine screening with endometrial biopsies and transvaginal ultrasonography for the detection of uterine cancer in asymptomatic women may lead to unnecessary invasive procedures. The researchers conducting these studies agree that these screening procedures should only be performed in women who have experienced any abnormal vaginal bleeding.

Women who are taking Tamoxifen may wish to speak with their physician about the risks and benefits of undergoing routine screening methods or about the participation in a clinical trial further evaluating appropriate screening methods.

(Journal of Clinical Oncology, Vol 18, Number 20, pp3457-3458, 3459-3463, 3464-3470, 2000).