Can Radiotherapy Reduce the Need for Axillary Surgery?

Radiotherapy to the axillary lymph node (AxRT) and axillary lymph node dissection (ALND) provide similar locoregional control after 10 years in patients with a positive sentinel lymph node, according to a new study. The significant reduction in lymphedema with the AxRT approach suggests that it should be considered a standard procedure.

“The standard paradigm is, if the sentinel node is clean, no further axillary surgery is indicated,” said Emiel J. T. Rutgers, MD, PhD, of the Netherlands Cancer Institute in Amsterdam. The AMAROS trial tested AxRT against ALND to see if some of the morbidity associated with surgery could be avoided; the 5-year results previously showed similar outcomes and less lymphedema with AxRT, but at that point it was underpowered with too few events to draw conclusions. Rutgers presented the new 10-year results at the San Antonio Breast Cancer Symposium (SABCS), held December 4–8 (abstract GS4-01).

Of 4,806 included patients, 1,425 had a positive axillary sentinel lymph node and were included in the intent-to-treat population; they were randomized between ALND (744 patients) and AxRT (681 patients). After exclusions for several reasons, a per-protocol population included 598 ALND patients and 535 AxRT patients, with a median follow-up of 10 years in both groups.

The median age in the study was 56 years in the ALND group and 55 years in the AxRT group, and over half of both groups were postmenopausal. More than 80% of both groups underwent breast-conserving surgery as their baseline treatment, and approximately 60% received chemotherapy. The median number of sentinel nodes removed was 2 in both groups.

The 10-year cumulative rate of axillary recurrence was 0.93% (7 of 744 patients) with ALND, and 1.82% (11 of 681 patients) with AxRT, for a hazard ratio (HR) of 1.71 (95% CI, 0.67–4.39; P = .365). Disease-free survival was also similar between the groups, with an HR of 1.19 (95% CI, 0.97–1.46; P = .105).

There was an increase in second primary cancers seen, at 75 with AxRT compared with 57 with ALND, for an HR of 1.45 (95% CI, 1.03–2.04; P = .035). In the AxRT group, 28.0% of these were contralateral breast cancer and 72.0% were at other sites; in the ALND group, these rates were 19.3% and 80.7%, respectively.

Rates of lymphedema were significantly lower with AxRT at 1, 3, and 5 years after treatment. Based on clinical observation and/or treatment, 29.4% of ALND patients and 14.6% of AxRT patients had lymphedema at 5 years (P < .0001).

“Both ALND and AxRT provide excellent and comparable locoregional control … after 10 years,” Rutgers said, “and there is significantly less lymphedema after AxRT after 5 years. AxRT can be considered a standard procedure.”

Virginia Kaklamani, MD, of UT Health San Antonio and co-chair of SABCS, who was not involved with the study, agreed with that conclusion. “You’re improving the morbidity of our patients, without compromising their outcomes,” she said. “The patients will live the same and have a very low risk of recurrence.” She noted that similar results showing low rates of recurrence have been available for at least a decade now, but changes to practice have been very slow to follow.