According to results presented at the 44th annual meeting of the American Society of Therapeutic Radiation Oncology (ASTRO), radiation therapy following a mastectomy in patients with positive axillary lymph nodes appears to reduce the rate of local-regional (near the breast) recurrences.
Women with breast cancer whose cancer has spread to several axillary (under the arm) lymph nodes often undergo a mastectomy (surgical removal of the breast) followed by chemotherapy. However, the role of radiation therapy to the breast following a mastectomy in this group of patients has been unclear.
Recently, researchers from the MD Anderson Cancer Center evaluated data involving women with positive axillary lymph nodes who received radiation to the breast following a mastectomy.The data included results from 5 clinical trials involving approximately 1,500 women. Of these women, 469 received radiation therapy following a mastectomy and were compared to 1,031 women who did not receive additional radiation therapy following a mastectomy. All patients were treated with Adriamycin® (doxorubicin)-based chemotherapy.
Researchers compared the results of women treated with radiation or not treated with radiation in four separate groups: 0, 1-3, 4-9 or greater than 10 positive axillary lymph nodes. In addition, the researchers compared the results of radiation therapy versus no radiation therapy in women with 20% or more positive examined lymph nodes and those with less than 20% positive examined lymph nodes. Approximately 10 years following therapy, radiation to the breast following a mastectomy reduced local-regional cancer recurrences from 5% to 0% in women with no positive lymph nodes; from 10% to 1.5% in women with 1-3 positive lymph nodes; from 21% to 2.4% in women with 4-9 lymph nodes and from 22% to 6.1% in women with 10 or more positive lymph nodes. Furthermore, there was a reduction of local-regional recurrences with the use of radiation therapy in patients with 20% or more positive examined lymph nodes from 27% to 4.2%. In women with cancer cells near the edges of the surgically removed cancer (versus a larger area of normal tissue), radiation therapy reduced local-regional recurrences from 45% to 13.3%. Recurrences in the chest wall were also reduced overall from 68% to 6.4%.
These researchers concluded that radiation therapy following a mastectomy in patients with breast cancer appears to drastically reduce the rate of local-regional recurrences, despite chemotherapy-based treatment. Women with increasing lymph node involvement or cancer cells near the edge of the surgically removed tissue appear to benefit most from post-mastectomy radiation. Patients with breast cancer who are to undergo a mastectomy and chemotherapy may wish to speak with their physician about the risks and benefits of post-mastectomy radiation therapy or the participation in a clinical trial evaluating further treatment options.
Reference: Woodward W, Katz A, Buchholz T, et al. Patterns and predictors of locoregional recurrence in 469 patients treated with post-mastectomy radiation.
International Journal of Radiation Oncology, Biology and Physics. 2002;54:91-92. Proceedings from the American Society of Therapeutic Radiation Oncology (ASTRO 2002).