Radiation to Internal Mammary Lymph Nodes Improves Cancer-Free Survival
According to a recent article published in the Journal of Clinical Oncology, radiation to the internal mammary lymph nodes following high-dose chemotherapy and autologous stem cell transplantation may improve cancer-free and overall survival in patients with stages II-III breast cancer.
Stages II and III breast cancer refers to cancer that has spread from the breast to nearby axillary (under the arm) lymph nodes, but not to distant sites in the body. Standard therapy typically consists of surgery to remove the cancer, followed by radiation therapy, chemotherapy and/or hormone therapy if appropriate, to kill any cancer cells remaining in the body following surgery. The concept of high-dose chemotherapy is to kill more cancer cells that may exist in the body, compared to conventional doses. However, the high doses also tend to kill more healthy cells, causing more side effects from treatment. Therefore, some physicians remain reluctant to utilize the approach of high-dose therapy. Although high-dose therapy is standard treatment for some cancers, it has remained controversial in the medical arena for the treatment of breast cancer. Researchers are beginning to sort out different patient or disease characteristics as well as subtle changes in treatment regimens that improve survival and tolerability of high-dose therapy.
One main side effect of high-dose therapy is low blood cell levels. The 3 main types of blood cells are red blood cells which carry oxygen to tissue in the body, white blood cells which fight infection and platelets which aid the blood in clotting. When blood cell levels are reduced to dangerous levels from high-dose treatments, the result may be life-threatening for patients. One approach to reduce or mitigate low blood cells levels from high-dose therapy is to collect immature blood cells, called stem cells, from the patient prior to high-dose therapy and re-infuse the cells directly following therapy. Stem cells can be collected from the bone marrow (spongy material inside large bones) or from peripheral blood. This approach is called an autologous stem cell transplant. Furthermore, research continues to progress, providing additional convenient supportive care therapy that helps to reduce or prevent low blood cells levels, including agents such as Neulasta or Aranesp that stimulate the production and maturation of white and red blood cells, making high-dose therapy safer.
Patients with stages II-III breast cancer undergoing high-dose therapy and a stem cell transplant are routinely given radiation therapy to the site of the breast cancer as well as the axillary (under the arm) and local lymph nodes to help rid the body of cancer cells. However, the role of radiation therapy to internal mammary lymph nodes (behind the breastbone) has remained controversial and is not routinely performed. Recently, researchers from Israel conducted a clinical study to determine if the addition of radiation to internal mammary lymph nodes may affect outcomes of patients with breast cancer undergoing high-dose chemotherapy and an autologous stem cell transplant. In this study, 100 women with stages II or III breast cancer received high-dose chemotherapy with an autologous stem cell transplant, radiation to the breast, axilla and lymph nodes near the neck (supraclavicular) as well as Nolvadex® (tamoxifen) if their cancer was hormone-positive. Sixty-seven of these patients also received radiation to the internal mammary lymph nodes. At approximately 6 ½ years after diagnosis, cancer-free and overall survival was superior in the group of patients treated with radiation to the internal mammary lymph nodes. Cancer-free survival was 73% in the group of patients treated with radiation to the internal mammary lymph nodes, compared to 52% in the group of patients not treated with the additional radiation. Overall survival was 78% in the group of patients treated with radiation to the internal mammary lymph nodes, compared to 64% for those not treated with radiation to the internal mammary lymph nodes. There were no treatment-related deaths.
These researchers concluded that the addition of radiation to internal mammary lymph nodes appears to improve cancer-free and overall survival in patients with stages II-III breast cancer undergoing high-dose chemotherapy and an autologous stem cell transplant. A large ongoing clinical trial in Europe may help provide a definitive conclusion on the role of radiation to internal mammary lymph nodes in patients with different stages of breast cancer. Results from this large trial are expected in a few years. Patients with stages II-III breast cancer may wish to speak with their physician about their individual risks and benefits of radiation therapy to internal mammary lymph nodes.
Reference: Stemmer S, Rizel S, Hardan I, et al. The Role of Irradiation of the Internal Mammary Lymph Nodes in High-Risk Stage II to IIIA Breast Cancer Patients After High-Dose Chemotherapy: A Prospective Sequential Nonrandomized Study.
Journal of Clinical Oncology. 2003;21:2713-2718.