Does adequate irradiation of the internal mammary chain and supraclavicular nodes improve survival rates?

Abstract

In all randomized trials of mastectomy alone versus mastectomy and irradiation, the survival rates were not improved with irradiation. In 1977 a randomized trial of patients who were treated with radical mastectomy alone or radical mastectomy followed by irradiation of the peripheral lymphatics with ⁶⁰Co showed these results; among the irradiated patients with histologically positive axillary nodes the proportion of patients free of disease was statistically significant, greater than in the control group. At M. D. Anderson Hospital the 10-year survival rates for patients who had peripheral lymphatic irradiation (65.75% with histologically positive axillary nodes) was 56% versus 54% for patients who were treated with radical mastectomy alone (11.5% with histologically positive axillary nodes). The average number of involved nodes per patient was almost the same in the two groups. Because survival rates correlate strongly with the percentage of patients with histologically positive axillary nodes, the survival rate would be expected to be much lower for the irradiated patients. Although the data is not from a randomized trial, it suggests strongly that the irradiation of peripheral lymphatics has been curative in a significant number of patients. A critical review of all the previous randomized trials shows that actually the internal mammary chain nodes and the nodes at the root of the neck, i.e. the nodes that are a direct route of spread of breast cancer, either have been missed completely by the portal arrangement or have received an uncertain dosage.