Postmastectomy Radiotherapy Benefits Women With Breast Cancer That Has Spread to One to Three Lymph Nodes

In women with breast cancer who had between one and three positive lymph nodes, radiotherapy reduced the recurrence rate by 32% and the breast cancer death rate by 20%.

Giving radiotherapy to these women 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.

These findings, which were presented at the 2014 European Breast Cancer Conference in Glasgow and published in The Lancet,¹ confirmed the benefit of radiotherapy after mastectomy in women with four or more positive nodes.

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, said Paul McGale, PhD, of the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) at the Clinical Trial Service Unit, Oxford. However, the findings showed that radiotherapy improves their chances of remaining disease-free and reduces their risk of dying from breast cancer.

“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 also to benefit from radiotherapy if they have any positive lymph nodes,” Dr. McGale said at a news briefing.

The benefit occurred regardless of whether the women were in trials where chemotherapy or hormonal therapy was given to all women. Sixty-five percent of women with one, two, or three positive nodes received chemotherapy, and a further 21% with hormone-sensitive tumors received hormonal therapy.

Absolute Benefits Remain to Be Seen

Carolyn Taylor, FRCR, a clinical oncologist in the EBCTCG, noted, “We will have to wait for results from new trials to observe directly the long-term effects of modern radiotherapy in women who are given modern chemotherapy and hormonal therapy. However, it is likely that the percentage reductions in disease recurrence and breast cancer mortality from today’s radiotherapy will be at least as big as the benefits seen here.”

Dr. McGale concluded, “Since the time when the women in these trials were randomized, there have been advances in radiotherapy and also in breast screening, surgery, lymph node staging, and systemic therapy. So the absolute benefits from postmastectomy radiotherapy today may be smaller than those we have reported here. But the proportional benefits from radiotherapy are likely to be at least as big.”

To investigate this and follow up on their findings, Dr. McGale, Dr. Taylor, and their colleagues are inviting investigators of more recent trials comparing different radiotherapy regimens to contribute data to the EBCTCG. ■

Reference

1. Early Breast Cancer Trialists’ Collaborative Group: Effect of radiotherapy after mastectomy and axillary surgery on 10-year recurrence and 20-year breast cancer mortality. Lancet. March 19, 2014 (early release online).