Axillary radiotherapy and axillary lymph node dissection achieved similar rates of regional control in patients with breast cancer who have a positive sentinel node, according to results of a randomized phase 3 trial.
However, radiotherapy was associated with significantly less morbidity.
Axillary lymph node dissection has been the standard treatment for patients with breast cancer who have a positive sentinel node. Dissection provides excellent control but also is associated with harmful side effects, according to background information provided by researchers.
In the current multicenter, open-label study, Mila Donker, MD, of the department of surgical oncology at Netherlands Cancer Institute, and colleagues assessed whether axillary radiotherapy provided comparable regional control with fewer side effects.
The analysis included 4,806 women with T1-T2 primary breast cancer and no palpable lymphadenopathy who were randomly assigned to axillary lymph node dissection or axillary radiotherapy in case of a positive sentinel node.
Researchers detected positive sentinel nodes in 1,425 (29.6%) of patients; of them, 744 were assigned axillary lymph node dissection and 681 were assigned axillary radiotherapy.
Noninferiority of 5-year axillary recurrence — considered to be no more than 4% for the axillary radiotherapy arm vs. an expected 2% in the axillary lymph node dissection arm — served as the primary outcome measure. Median follow-up was 6.1 years.
Axillary recurrence occurred in four patients assigned axillary lymph node dissection and seven patients assigned axillary radiotherapy. Researchers reported 5-year axillary recurrence rates of 0.43% (95% CI, 0-0.92) after axillary dissection and 1.19% (0.31-2.08) after axillary radiotherapy.
Donker and colleagues observed no significant differences in DFS and OS between treatment arms.
They reported 124 DFS events in the dissection arm and 134 events in the radiotherapy arm. At 5 years, the DFS rate was 86.9% (95% CI, 84.1-89.3) among those assigned axillary lymph node dissection and 82.7% (95% CI, 79.3-85.5) among those assigned axillary radiotherapy (HR= 1.18; 95% CI, 0.93-1.51).
Five-year OS was 93.3% (95% CI, 91-95) among those who underwent dissection and 92.5% (90-94.4) among those who underwent radiotherapy (HR=1.17; 95% CI, 0.85-1.62).
Lymphedema in the ipsilateral arm was significantly more common after dissection than radiotherapy at 1 year (28% vs. 15%; P<.0001), 3 years (23% vs. 14%; P=.003) and 5 years (23% vs. 11%; P<.0001).
Circumference increases of ≥10% in the ipsilateral upper arm, ipsilateral lower arm or both also was more common in the dissection group at 1 year (8% vs. 6%; P=.497), 3 years (10% vs. 6%; P=.08) and 5 years (13% vs. 6%; P=.0009).
“[This trial] cannot answer the remaining question of which subset of clinically node-negative, sentinel-node-positive patients still require axillary treatments,” Donker and colleagues wrote. “In our opinion, if further axillary treatment is needed in clinically node-negative, sentinel-node-positive patients, axillary radiotherapy could be chosen instead of axillary lymph node dissection because it provides comparable axillary control and less morbidity.”
Disclosure: The researchers report no relevant financial disclosures.