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Brachytherapy after surgery for stage I endometrial cancer appears to be an effective alternative to external beam radiation therapy, according to a study published in the International Journal of Radiation, Oncology, Biology, Physics.

Endometrial cancer refers to cancer that begins in the lining of the uterus (endometrium), or womb. With approximately 36,100 new cases each year, endometrial cancer is one of the most common gynecologic cancers in women. Patients diagnosed with Stage I uterine cancer have cancer that has not spread outside the uterus. Stage IA is cancer confined to the inner layer of cells of the uterus (endometrium). Stage IB is cancer that invades less than one half of the muscle wall of the uterus. Stage IC is cancer that invades more than one half of the muscle wall of the uterus.

The standard treatment for stage I uterine cancer is a total abdominal hysterectomy (removal of the uterus) and bilateral salpingo-oophorectomy (removal of the fallopian tubes and ovaries). In some cases, lymph nodes are also removed. Despite complete surgical removal of all detectable cancer, 5 to 20% of patients will experience recurrence of their cancer. This is because some patients with stage I cancer have microscopic cancer cells, called micrometastases, that have spread outside the uterus and therefore were not removed by surgery. These cancer cells cannot be detected with any of the currently available tests. Micrometastases can cause relapses that follow treatment with surgery alone. Following surgery, some patients may benefit from additional treatment (adjuvant therapy) to decrease the risk of cancer recurrence. Many women are treated with adjuvant radiation therapy.

There are currently two types of radiation therapy in common use; external beam radiation therapy (EBRT) and brachytherapy. External beam radiation therapy is given via machines called linear accelerators, which produce high-energy radiation beams outside of the body that penetrate the tissues and deliver the radiation dose deep into the areas where the cancer resides. With brachytherapy, radiation is given through radioactive pellets or “seeds” that are placed near the site of the cancer. Brachytherapy is commonly used to treat prostate cancer in men. In the case of endometrial cancer, the radioactive pellets are placed in the vagina, after hysterectomy, to prevent cancer recurrence in the vaginal cuff. The vaginal cuff is the upper part of the vagina, and a common site of cancer recurrence. A benefit of brachytherapy is that it doesn’t require frequent visits to the doctor in order to deliver the radiation. It may also be associated with fewer side effects than EBRT.

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To evaluate the frequency of cancer recurrence after surgery and brachytherapy, researchers at the Mayo Clinic evaluated 100 women with stage I endometrial cancer. All had received adjuvant vaginal brachytherapy. With over half of the women now followed for more than 23 months since treatment, there has not been a single case of cancer recurrence in the pelvis or vagina. Side effects of brachytherapy were generally mild and include changes to the lining of the vagina, temporary urinary irritation, and temporary diarrhea.

Because this study did not directly compare brachytherapy to EBRT, and patients have not been followed for several years, it is not possible to unequivocally conclude that brachytherapy is equal or superior to EBRT. Nevertheless, vaginal brachytherapy appears to be a safe and effective alternative to EBRT for women with stage I endometrial cancer. Patients may wish to inquire about the results of ongoing studies and the role vaginal bracytherapy may play in the management early-stage endometrial cancer.

Reference: Solhjem MC, Petersen IA, Haddock MG. Vaginal brachytherapy alone is sufficient adjuvant treatment of surgical stage I endometrial cancer. International Journal of Radiation, Oncology, Biology, Physics. 2005;62:1379-1384.