Study Finds Radiation Therapy May be Better Than Tamoxifen for Early-Stage Breast Cancer (dateline October 25, 2002)
A newly published study by British researchers finds that women who are diagnosed with an early form of breast cancer called ductal carcinoma in situ (DCIS) may be less likely to experience a recurrence of their disease if they are treated with radiation after breast cancer surgery, rather than with the drug tamoxifen. In the study, women who were treated with radiation were 60% less likely to have their cancer return after treatment, versus a reduction in risk of only 10% for the women who were treated with tamoxifen. Though there has been controversy as to whether women with early-stage breast cancer need more aggressive treatments, such as radiation, the results of this study suggest that women who receive radiation after surgery fare better than those who receive drug therapy alone.
DCIS is the most common type of non-invasive breast cancer, in which the cancer cells are confined to milk ducts in the breast and have not spread into the fatty breast tissue or to any other part of the body (such as the lymph nodes). When treated properly with surgery, either lumpectomy or mastectomy, the chances of surviving DCIS are nearly 100%. However, many women with DCIS do experience a recurrence of the disease at a later point.
Tamoxifen is a drug used to help treat or prevent breast cancer and to help reduce the risk that breast cancer will return after treatment. Many women with DCIS are treated with tamoxifen. Radiation therapy is also commonly used after a lumpectomy to also help reduce the risk of a cancer recurrence.
To compare the effectiveness of tamoxifen and radiation therapy in women diagnosed with DCIS, Professor Jack Cuzick and researchers from the British charity Cancer Research UK analyzed results from an ongoing study of 1,700 women from the United Kingdom, Australia and New Zealand who have been studied since 1990.
The results of the study found that the risk of developing breast cancer in the same breast after treatment was significantly lower among the DCIS patients treated with radiation therapy alone (after surgery), compared with those who were treated with tamoxifen. Radiation therapy also reduced the risk of a cancer recurrence in women with invasive breast cancercancer which has spread beyond the breast ducts.
"It is clear that radiotherapy is needed for the majority of women with DCIS. Tamoxifen should be limited to women who have estrogen sensitive cancers," said Professor Jack Cuzick, in a Cancer Research UK news release. "Treatment is given after complete local excision, which is also known as lumpectomy. The main difference for women is that radiotherapy involves an intensive course of treatment for five weeks whereas tamoxifen is given as a pill for five years."
Both radiation therapy and tamoxifen are associated with some side effects. The most common side effects of radiation include fatigue, breast swelling, and a temporary sunburn-like appearance of the breast. Side effects of tamoxifen include hot flashes and vaginal dryness. Tamoxifen is also associated with some rare but potentially serious problems, including an increased risk of endometrial cancer (cancer of the uterine lining), stroke, and blood clots.
The researchers did emphasize that tamoxifen may still be needed for women with estrogen-sensitive breast cancers. Tamoxifen works by blocking estrogen from reaching breast cancer cells, thereby starving these cells. The drug is effective only in women whose cancers have estrogen receptors (approximately 80% of breast cancers). In addition, most physicians recommend radiation therapy for the majority of women who are treated with lumpectomy.