CHICAGO - Breast cancer patients who receive radiation treatment to the lymph nodes located behind the breast bone do not have better survival outcomes than patients who don't receive radiation in this difficult-to-treat area.
That's the conclusion of a randomized 10-year study presented today at the annual meeting of the American Society for Radiation Oncology (ASTRO).
The phase III trial is the first to compare chest wall, axillary, and supraclavicular irradiation with and without internal mammary chain radiation in newly diagnosed stage I and II breast cancer patients with positive axillary nodes or tumors located in an internal, central location in the breast.
The patient cohort included 1,334 women treated at French radiation oncology centers in Besançon, Dijon, Lyon, Montpellier, Nice, and Paris. They were randomly assigned to receive conventional electron-beam radiation therapy (EBRT) or EBRT with additional internal mammary chain irradiation. All patients had mastectomies prior to treatment, and an unspecified number also received adjuvant chemotherapy and/or hormonal treatment.
The patients who received the internal mammary chain irradiation received a dose of 12.5 Gy photons in five fractions and 32.5 Gy electrons in 13 fractions over a five-week time period to a target area of the first five intercostal spaces, according to lead author Dr. Pascale Romestaing, a radiation oncologist at the Centre de Radiothérapie Mermoz in Lyon.
The patients were followed for a median of 10 years, with 371 patients, or 27.8%, dying of breast cancer. The group that received EBRT and internal mammary chain irradiation had a survival rate of 62.57% as compared to the control group, which had a survival rate of 59.55%, which the researchers said was not statistically significant.
There also were no statistically significant differences in survival rates between patients with positive (75%) or negative (25%) axillary nodes, external versus central or internal tumors, or according to different histological subtypes. In this patient cohort, receipt or nonreceipt of chemotherapy and/or hormonal therapy also did not change survival outcomes.
In spite of the higher risk of toxicities to the heart and lungs, Romestaing reported that patients who received the internal mammary chain irradiation had no increase in cardiac toxicity compared to the other group.
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