Results from the international randomised trial, carried out by the European Organisation for the Research and Treatment of Cancer (EORTC) and which involved 4004 patients with stage I to III breast cancer from 43 centres, are convincing, he says. "Our results make it clear that irradiating these lymph nodes gives a better patient outcome than giving radiation therapy to the breast/thoracic wall alone. Not only have we shown that such treatment has a beneficial effect on disease control, but it also improves breast-cancer related survival," he will tell the meeting.
Lymphatic drainage from breast cancer to the regional lymph nodes means that the cancer is more likely to spread to other parts of the body. This drainage follows two pathways. The best known is to the axilla (armpit), and these lymph nodes are usually treated by surgery and/or radiation therapy. The second pathway drains to the internal mammary (IM) lymph nodes behind the breast bone, and probably from there to those just above the collar bone, the medial supraclavicular (MS) nodes. Because of uncertainty about the effects of treatment in this area, and particularly concerns about the increased toxicity that might be caused by the irradiation of a larger area, until recently only about half of radiation oncology centres treated the IM-MS lymph nodes.
After a median follow-up of 15.7 years, the researchers found a significant reduction in deaths from breast cancer (16.0% in the treatment group vs. 19.8% in the control group), and in the return of breast cancer in patients who had received radiation to the IM-MS nodes (24.5% vs. 27.1%). A total of 1117 patients had died during the time. Overall survival was 73.2% in the IM-MS group and 70.8% in the control group. There was no increase in non-breast cancer related mortality in the first group and to date there has been no increased level of serious complications related to the treatment. There was no difference in the incidence of second cancers, cancer in the other breast, or deaths from cardiovascular disease between the two groups.