Additional Radiation Reduces Local Recurrences in Early Stage Breast Cancer
A study recently published in the New England Journal of Medicine suggests that an additional dose of radiation following a lumpectomy in women with early stage breast cancer reduces the rate of local cancer recurrences, particularly in women under 50 years old.
Breast cancer is a common malignancy among women in the United States with almost 200,000 new cases diagnosed each year. Breast cancer develops from cells in the breast and is defined according to various stages of progression. Patients diagnosed with stage I invasive breast cancer have a single location of cancer less than 2 cm (3/4 inch) in size that has not spread to the axillary (armpit) lymph nodes or sites distant from the breast. Patients diagnosed with stage II breast cancer have a primary cancer that either involves axillary lymph nodes and is less than 5cm (2 inches) in size, or is greater than 2 centimeters (3/4 inch) in size and does not involve any axillary lymph nodes. Stage I and II breast cancers are commonly referred to as early breast cancer.
Standard treatment of early stage breast cancer consists of a lumpectomy followed by radiation therapy. A lumpectomy, also known as conservation surgery, is surgery that removes only the cancer and surrounding tissue, leaving the majority of the breast intact. The purpose of a lumpectomy is to limit the amount of breast tissue removed, thereby reducing the disfigurement associated with removal of the entire breast. Following a lumpectomy, the most common location of a cancer recurrence is in the breast tissue in the vicinity of the primary cancer (local recurrence). Therefore, radiation therapy is used following a lumpectomy to kill cancer cells that may not have been removed during surgery, thereby reducing chances of a cancer recurrence.
Standard radiation therapy following a lumpectomy consists of a limited dose of radiation (50 Gy) to the entire affected breast. While this treatment leads to long-term outcomes similar to a mastectomy (complete removal of the breast), women under 50 years of age experience higher rates of local recurrences following this treatment regimen compared to their elder counterparts. Researchers theorized that an additional boost of radiation aimed only at the area in which the cancer was removed would reduce the rates of local recurrences, especially in younger patients.
The European Organization for Research and Treatment of Cancer conducted a clinical trial evaluating 5,318 women diagnosed with stage I or II breast cancer who had undergone a lumpectomy followed by the standard dose of radiation. Approximately half of the patients were given an additional small dose of radiation (16 Gy) where the cancer had been located, while the other half received no additional treatment.
The researchers followed the women for an average of 5.2 years. Data indicated that the additional dose of radiation to the site of the removed cancer reduced the overall rate of a local recurrence by nearly 50%. Women 40 years old and younger exhibited the largest benefit, with local recurrences occurring in only 10.2% of patients receiving additional radiation, compared to 19.5% of those receiving standard treatment. However, a reduced rate of local recurrences was demonstrated in all age groups. Overall survival rates and the incidence of distant metastases were similar whether women received an additional boost of radiation or standard therapy. Adjuvant system treatment (e.g., chemotherapy, hormonal therapy, etc.) did not affect the rates of local recurrences in either group. Side effects including cosmetic results and fibrosis (formation of scar tissue) were not affected by the additional radiation.
This study suggests that women receiving additional radiation following standard treatment for early breast cancer have fewer local recurrences of breast cancer, especially if they are under 50 years of age. Longer follow-up is needed to determine if these results translate into survival benefits. Women diagnosed with early breast cancer may wish to speak with their physician regarding the benefits of additional radiation or about participating in clinical trials further evaluating this issue. Two sources of information regarding ongoing clinical trials include comprehensive, easy-to-use listing services provided by the National Cancer Institute (cancer.gov) and www.eCancerTrials.com. eCancerTrials.com also provides personalized clinical trial searches on behalf of patients. (New England Journal of Medicine, Vol 345, No 19, pp 1378-87, 2001)
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