ASCO: Fewer Side Effects With Radiotherapy Alone for Some Node-Positive Breast Cancer Patients

June 5, 2013

A study presented at ASCO shows that axillary radiotherapy results in similar outcomes to axillary lymph node dissection, but halved the incidence of lymphedema.

While thousands of women have axillary lymph node dissection (ALND) to prevent recurrence of their breast cancer, the treatment has significant side effects, including lymphedema. A new European study presented at the annual meeting of the American Society of Clinical Oncology (ASCO) shows that an alternative approach results in similar outcomes but without the lymphedema, a long-term painful swelling in the arm when lymph tissue cannot be drained properly, for which there is no cure. The trial was coordinated by the European Organisation for Research and Treatment of Cancer (EORTC).

“Radiotherapy may be a better alternative to surgery because of the minimization of lymphedema,” said Emiel J. Rutgers, MD, a surgical oncologist at the Netherlands Cancer Institute in Amsterdam, and lead study author and presenter of the findings, in a press conference at the ASCO meeting.

Lymphedema is a serious, debilitating, and common side effect that affects long-term quality of life for patients, noted Rutgers. “I am sure these findings will lead to many doctors rethinking their strategy for treating patients who have a positive sentinel lymph node biopsy,” said Rutgers in a statement.

The phase III AMAROS (After Mapping of the Axilla: Radiotherapy or Surgery?) trial found that axillary radiotherapy was the same as ALND in terms of overall survival at 5 years after therapy for women with sentinel lymph node–positive early breast cancer (92.52% vs 93.27%, respectively). The 5-year axillary recurrence rate was 0.54% (4/744) after ALND compared with 1.03% (7/681) after axillary radiotherapy. The median follow-up was 6.1 years. “This [recurrence rate] was far less than anticipated by us as clinicians and by our statisticians when we designed the trial 12 years ago,” said Rutgers during the press conference. The disease-free survival rate at 5 years was also comparable (86.9% for ALND vs 82.65% for radiotherapy).

The planned noninferiority test was underpowered due to an unexpectedly low number of recurrences and deaths, the study authors noted.

From 2001 to 2010, 4,806 patients with early-stage, invasive, but clinically node-negative breast cancer were enrolled and randomized to study the difference between ALND treatment and axillary radiotherapy. When a sentinel node is found positive for breast tumor cells, surgical removal of the axillary lymph nodes is the standard treatment for patients. Of the patients enrolled who had a positive sentinel node biopsy, 744 were randomly assigned to ALND and 681 to axillary radiotherapy.

A greater incidence of lymphedema occurred after ALND compared with axillary radiotherapy. At 1 year, 40% of ALND patients had lymphedema compared with 22% who had undergone axillary radiotherapy (P < .0001). At 5 years, 28% of patients in the ALND arm had lymphedema compared with 14% of axillary radiotherapy patients (P < .0001). Swelling and arm movement were better in terms of patients’ quality of life in the radiotherapy arm compared with the surgery arm. No other differences in quality of life were detected.

“The results are fascinating,” said Timothy Michael Zagar, MD, associate director of the CyberKnife Radiosurgery Program at the University of North Carolina School of Medicine, who was not involved with the study. “Before any practice decisions are made, these results must be thoroughly analyzed in manuscript form,” Zagar cautioned. Zagar also noted that these results should be compared with the results of the NCIC-CTG MA.20 trial that demonstrated an overall survival benefit with the addition of regional nodal radiation to patients who had sentinel node surgery.

According to Rutgers, the women will continue to be followed for at least another 5 years to assess any latent side effects.

If these results are confirmed, many radiation oncologists will likely opt for radiation treatment rather than surgery to minimize lymphedema, said Zagar.