Radiotherapy after mastectomy improves outcomes for patients with up to three positive lymph nodes
Women whose breast cancer has spread to just a few axial lymph nodes are less likely to have their disease recur or to die from it if they have radiotherapy after mastectomy, according to new research. This study was presented at the European Breast Cancer Conference in Glasgow, Scotland, and was published in The Lancet (2014; doi:10.1016/S0140-6736(14)60488-8).
Until now, there has been uncertainty over whether women with early breast cancer that has spread to just one, two, or three lymph nodes under the arm gain any benefit from radiotherapy after surgery, explained Paul McGale, PhD, of the Early Breast Cancer Trialists' Collaborative Group at the Clinical Trial Services Unit in Oxford, United Kingdom.
"Another result from our study is that the proportional benefits of radiotherapy were similar in women regardless of whether or not they had also received chemotherapy or hormonal therapy. This is important because most women today receive these therapies. Our results suggest that women being treated today are likely to also benefit from radiotherapy if they have any positive lymph nodes," said McGale.
The research team analyzed results from 3,786 women in 14 randomized trials starting between 1964 and 1982. The women had underwent mastectomy along with the surgical removal of lymph nodes under the arm (axillary dissection) and were then randomized to either radiotherapy to the chest wall and surrounding regions or no radiotherapy. The women 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. The women were followed for an average of a little more than 11 years, and data on the number of recurrences and deaths were available up to 2009.
"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," said McGale. "However, 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%).” In this group of women, radiotherapy led to nearly 12 fewer recurrences of breast cancer per 100 women after 10 years, and eight fewer deaths per 100 women after 20 years.
Percentage reductions in the recurrence and death rates in the 405 women who had only one positive lymph node were similar to those for the women who had two or three positive lymph nodes. For the 1,772 women with four or more positive nodes, radiotherapy also reduced the recurrence rate (by 21%) and the breast cancer death rate (by 13%).
The benefit occurred regardless of whether or not the women were in trials where chemotherapy or hormonal therapy was given to all women. Chemotherapy was received by 65% of women with one, two, or three positive lymph nodes, and a further 21% with hormone-sensitive tumors received hormonal therapy.