Patients with breast cancer treated with tamoxifen worry the drug may induce development of a second cancer, endometrial cancer or cancer of the uterine lining. In an attempt to detect these cancers earlier, clinicians typically screen tamoxifen users on a regular basis.
But two new studies now report that the most common screening techniques – tissue biopsies and transvaginal ultrasound – are ineffective in detecting endometrial cancer at its earliest stage.
Study 1:
Screening endometrial biopsies, commonly used in the U.S., are no better than careful observation
Women with breast cancer who are taking Tamoxifen should be told that regular uterine biopsies are no more effective at detecting early endometrial cancer than waiting for the development of abnormal bleeding, researchers from Memorial Sloan-Kettering Cancer Center said.
The study of 111 patients using tamoxifen who underwent 635 uterine biopsies – a biopsy of the uterine tissue lining – found the test picks up very few abnormalities and often leads to unnecessary procedures. Test results from fourteen patients (12.6 percent) indicated an abnormality (none of which were cancer) and three patients underwent a hysterectomy. But in the end, there were no patients who had a cancer detected by endometrial biopsy.
“This is good news for the hundreds of thousands of women now on the drug, as well as the 80,000 women who annually start using it,” said the study’s leader, Richard Bakarat, M.D. “It means these patients don’t have to be subjected to a battery of tests which we now know of are limited value.”
The annual risk of endometrial cancer is two per 1,000 women in this population, and approximately 15% of these cancers result in the patient’s death. Thus, annual screening could potentially decrease mortality in only .03% of all tamoxifen-treated patients, the researchers said.
“The bottom line is that the risk of developing endometrial cancer due to tamoxifen is outweighed by its potential benefits for breast cancer treatment. Patients should be reassured by their physicians and instructed to report any episode of abnormal vaginal bleeding so that they can undergo an endometrial biopsy,” says Dr. Barakat. “And if endometrial cancer is detected, it is usually at an early stage when it is highly curable.”
“Effect of Adjuvant Tamoxifen on the Endometrium in Women With Breast Cancer: A Prospective Study Using Office Endometrial Biopsy;” R.R. Bakarat, M.D., et al.; Memorial Sloan-Kettering Cancer Center, New York, NY. Vol. 18, No. 20, (October) 2000, ppxxxx-xxxx.
Study 2:
German study finds ultrasound test results in unnecessary surgery
German researchers reported that a popular ultrasound screening test used in Europe to detect endometrial cancer in breast cancer patients who use tamoxifen is ineffective, and should no longer be used. Patients should instead monitor themselves for abnormal bleeding, a telltale symptom of the cancer.
The test, called TVS (transvaginal ultrasound), detected only one case of endometrial cancer from 1,265 screenings in 345 postmenopausal German women who were tested twice a year for five years. Conversely, two others cases of cancer were detected between screenings, because of bleeding.
Even worse, the test produced “false positive” results that led to the over-interpretation of risk and unnecessary surgery. All 52 patients with thick or suspicious-looking endometrial tissue had uterine tissue removed for examination by hysterectomy and a D&C procedure, resulting in perforation of the uterus in four patients. This was the group in which only one cancer was found without the telltale sign of bleeding.
The misdiagnosis is due to a tamoxifen-induced thickening of the endothelial lining, which can appear as early cancerous growth on a sonographic image, says the study’s lead author, Bernd Gerber, M.D., of the University of Rostock.
But development of endometrial cancer due to tamoxifen is much less rare than once believed, and the first symptom is usually vaginal bleeding, said Gerber.
“Unfortunately, this warning sign is very often ignored,” he said. “In Germany and in most European countries, TVS is the most important tool for endometrial screening.”
If discovered due to bleeding, treatment typically offers a good prognosis, Gerber says.
“Effects of Adjuvant Tamoxifen on the Endometrium in Postmenopausal Women With Breast Cancer: A Prospective Long-Term Study Using Transvaginal Ultrasound;” Bernd Gerber, M.D., et al.; University of Rostock, Germany. Vol. 18, No. 20, (October) 2000, pp. xxxx-xxxx.
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