Radiotherapy to the axilla may replace axillary lymph node dissection for local tumor control in selected patients with sentinel node–positive breast cancer, sparing many patients lymphedema, according to the final results of the European Organisation for Research and Treatment of Cancer (EORTC) AMAROS trial presented at the ASCO Annual Meeting.¹

“If radiation therapy is deemed necessary due to large tumor size and/or positive sentinel lymph nodes, you can radiate the axilla at the same time and achieve similar local control as full lymph node dissection in the axilla. Radiotherapy to the axilla should be the standard of care. We are doing this in the Netherlands as an alternative treatment option. We know that axillary lymph node dissection is associated with high rates of side effects,” said lead author Emiel J. Rutgers, MD, PhD, a surgical oncologist at the Netherlands Cancer Institute in Amsterdam.

Study Rationale

It is important to treat patients with a positive sentinel lymph node early to achieve regional tumor control and improve prognosis, Dr. Rutgers said. In many countries, including the United States, the current standard of care for many patients with positive sentinel lymph nodes is further resection of additional axillary lymph nodes to prevent recurrence of cancer in the axilla (and treatment of the remaining nodes if deemed necessary).

This study was designed to compare axillary dissection with radiotherapy to the axilla 12 years ago, with the goal of lessening toxicity including lymphedema, impairment of shoulder movement, and reduced quality of life, he explained. The study employed radiation techniques in use at the time the study was designed, but researchers are now studying ways to deploy modern techniques, so as to reduce side effects further.

AMAROS included 4,806 patients, with tumors up to 5 cm and no palpable lymph nodes; 1,425 (29.7%) had a positive axillary node on sentinel node dissection. In an intent-to-treat analysis, 744 patients were randomly assigned to lymph node dissection and 681, to axillary radiotherapy. About 85% of both groups received treatment as assigned.

Key Data

At a median follow-up of 6.1 years, the risk of axillary relapse was low in both groups: 0.54% (4 patients) in the surgery group and 1.03% (7 patients) in the radiotherapy group. Disease-free survival rates were similar. No difference was seen in overall survival. Breast cancer-related deaths were reported in 53 patients (7.1%) in the surgery group vs 54 patients (7.9%) in the radiotherapy group.

The rates of lymphedema were assessed at years 1, 3, and 5 following treatment. Patients assigned to radiotherapy had significantly lower lymphedema rates at all time points. At 1 year, 40% of the surgery group and 21.7% of the radiotherapy group had lymphedema; at 3 years, 29.8% and 16.7%, respectively; at 5 years, 28% and 13.6%, respectively. These differences were highly statistically significant (P < .0001 for all comparisons favoring radiotherapy).

No difference in shoulder function was observed between the groups, although a trend was seen for impaired shoulder function in the radiotherapy group only during the first year after therapy. Evaluation of quality of life using the EORTC-QLQ-C30 and the QLQ-BR23 breast cancer module revealed no difference between groups. ■

Disclosure: Dr. Rutgers reported no potential conflicts of interest.

Reference

1. Rutgers EJ, Donker M, Straver ME, et al: Radiotherapy or surgery of the axilla after a positive sentinel node in breast cancer patients: Final analysis of the EORTC AMAROS trial (10981/22023). ASCO Annual Meeting. Abstract LBA1001. Presented June 3, 2013.