Women whose breast cancer has spread to just a few lymph nodes under their arm can benefit from having radiotherapy after mastectomy, according to new research presented at the European Breast Cancer Conference in Glasgow, Scotland, and published online on 19 March in the journal Lancet.
Study lead Dr. Paul McGale of the Early Breast Cancer Trialists' Collaborative Group at the Clinical Trial Service Unit in Oxford, U.K., and colleagues considered results from 3,786 women in 14 randomized trials that were conducted between 1964 and 1982. The women had undergone mastectomies along with the surgical removal of lymph nodes under the arm and were then randomized to receive either radiotherapy to the chest wall and surrounding regions or not to receive radiotherapy (Lancet, 19 March 2014).
Study participants fell into three categories: those with no cancer in the lymph nodes; those with cancer in one, two, or three lymph nodes; and those with cancer in four or more lymph nodes. They were followed up for an average of just over 11 years, and data on the number of recurrences and deaths were available up to 2009, according to McGale's team.
In 700 women in whom the pathologists could find no sign that the nodes were affected, radiotherapy did not reduce the risk of recurrence or of dying from breast cancer. But in the 1,314 women who had between one and three positive nodes, radiotherapy reduced the recurrence rate by nearly a third (32%) and the breast cancer death rate by a fifth (20%), McGale and colleagues discovered. As for the 1,772 women with four or more positive nodes, radiotherapy also reduced the recurrence rate and the breast cancer death rate by 21% and 13%, respectively.
"It is already accepted that women with four or more positive nodes benefit from radiotherapy after mastectomy, and these findings confirm this benefit," McGale said in a statement released by the European CanCer Organisation (ECCO), sponsor of the conference. "However, it is for women with between one and three positive nodes where the previous evidence has been unclear. Our findings show that radiotherapy improves their chances of remaining disease-free and reduces their risk of dying from breast cancer."
