ECC 2013: Radiation to Chest Lymph Nodes Improves Survival in Early Breast Cancer
Extending radiation to the lymph nodes behind the sternal wall and above the collarbone extends overall survival in patients with stage I to III breast cancer and does not increase toxicity compared to conventional locoregional radiation therapy, according to 10-year results of an international randomized trial reported at the European Cancer Congress 2013 in Amsterdam (Abstract 2).
“Our results make it clear that irradiating these lymph nodes gives a better patient outcome than giving radiation to the breast/thoracic wall alone. Not only have we shown that such a treatment has a beneficial effect on locoregional disease control, but it also improves distant metastasis–free survival and overall survival,” said Philip Poortmans, MD, PhD, a radiation oncologist from the Instituut Verbeeten, Tilburg, The Netherlands.
“Based on these results, we advise radiation therapy to the internal mammary and medial supraclavicular lymph nodes for patients with involved axillary lymph nodes and/or a medially located primary tumor.”
Dr. Poortmans said that radiation to the internal mammary and medial supraclavicular lymph nodes is not typically done in the United States and in Europe. His center is the only one in The Netherlands to offer this treatment to high-risk patients. In the study, the low-risk patients had especially good outcomes with this strategy, he noted.
Study Details
The study was conducted to determine the relative contribution of radiation to the internal mammary and medial supraclavicular lymph nodes to the overall survival benefit of locoregional radiation therapy in stage I to III breast cancer. 4,004 patients with involved axillary lymph nodes and/or a medially located primary tumor were randomly assigned at 43 centers in 13 countries between 1996 and 2004 to receive conventional radiation therapy or radiation that included the internal mammary and medial supraclavicular lymph nodes to 50 Gy in 25 fractions.
About 55% of patients had involved axillary lymph nodes at baseline. Following mastectomy, 73.2% of patients in both arms received chest wall radiation; axillary radiation therapy was given to 6.8% of the no internal mammary and medial supraclavicular arm and 7.8% in the internal mammary and medial supraclavicular arm. Adjuvant systemic chemotherapy was given to 99% of the lymph node–positive and 66.3% of the lymph node–negative patients.
Improved Survival Outcomes
At a median follow-up of 10.9 years, actuarial overall survival was 82.3% in the internal mammary and medial supraclavicular group vs 80.7% in the no internal mammary and medial supraclavicular group, representing a nonsignificant 13% relative reduction in risk of death. Treatment effect was independent of the number of involved lymph nodes.
There were 382 deaths in the internal mammary and medial supraclavicular group vs 429 in the no internal mammary and medial supraclavicular group. Except for breast cancer deaths, causes of death were similar (259 vs 310 breast cancer deaths, respectively).
The effect on survival was significant when adjusted for stratification factors. The effect of extended radiation to the internal mammary and medial supraclavicular lymph nodes was especially evident on distant metastases, which occurred in 15.9% of those who had radiation to the internal mammary and medial supraclavicular lymph nodes vs 19.6% for those who did not have internal mammary and medial supraclavicular radiation.
Disease-free survival was 72.1% in those who received internal mammary and medial supraclavicular radiation vs 69.1% in those with no internal mammary and medial supraclavicular radiation (P = .044), and metastasis-free survival was 78% vs 75%, respectively (P = .02).
At follow-up, no increased toxicity was observed in the internal mammary and medial supraclavicular patients.
The investigators plan to follow the patients for an additional 10 years, for a total of 20 years. The next analysis will be presented at 15 years.
At the opening press conference, Cornelis Van de Velde, MD, an oncologic surgeon who is President of ECCO and Congress Chair, said, “This study on breast cancer surprised me a lot. Previous surgical studies showed no difference in survival with internal mammary and medial supraclavicular radiation. We will have to consider how to change strategy and implement these findings in our guidelines.”
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