Ten-year Results of a Randomized Trial of Internal Mammary Chain Irradiation after Mastectomy

Article Outline

• Purpose/Objective(s)
• Materials/Methods
• Results
• Conclusions
• Copyright

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Purpose/Objective(s) 

To evaluate the impact of internal mammary chain irradiation (IMC-RT) on long-term survival in breast cancer patients treated with mastectomy.

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Materials/Methods 

Multicentric randomized Phase III trial comparing chest wall, axillary, and supra-clavicular irradiation with or without IMC-RT in newly diagnosed Stage I and II breast cancers. Inclusion criteria: patients under 76-years-old with positive axillary nodes or internal/central tumor location whatever pN. Stratification was done by center, nodal status, and tumor location (internal/central vs. external). The IMC-RT consisted in a combination of photons (12.5 Gy in 5 fractions) and electrons (32.5 Gy in 13 fractions) over 5 weeks. The target field included the first five intercostal spaces. Adjuvant chemotherapy or hormonal treatment was at the discretion of the physician. We planned to include 1,200 patients that allowed us to detect 10% difference in 10-year overall survival.

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Results 

A total of 1,334 patients have been randomized. Mean age was 56.5-years-old, 1,003 (75%) patients had positive lymph nodes. With a median follow-up of 10 years, we observed 535 deaths. Ten-year survival was 62.57% in case of IMC-RT and 59.55% without IMC-RT (p = 0.8762 by log–rank test). No difference was obtained in the different subgroups: positive or negative axillary nodes, external vs. central/internal tumors, or according to the different histologic subtypes, adjuvant chemotherapy, or hormonotherapy. Causes of death are known in 422 patients: most of these deaths were due to breast cancer (371); no increase in cardiac toxicity was observed in the IMC-RT group.

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Conclusions 

Using IMC-RT did not improve overall survival in this large randomized study.