SAN ANTONIO — The 10-year follow-up of the controversial AMAROS study appeared to confirm that irradiating the axilla after a positive sentinel node diagnosis is as good in preventing breast cancer recurrence as lymph node dissection, and reduced the risk of lymphedema by 50%, researchers reported here.
After 10 years, 7 of 744 women who underwent lymph node dissection experienced a recurrence in the axilla compared with 11 of 681 women who underwent radiotherapy (P=0.37), according to Emiel Rutgers, MD, PhD, of the Netherlands Cancer Institute in Amsterdam.
At a press conference at the annual San Antonio Breast Cancer Symposium (SABCS), Rutgers said that the rate of overall survival at 10 years was similar between the two groups (84.6% with surgery vs 81.4% with radiotherapy, P=0.26).
What was different between the groups, he noted, was the debilitating adverse event of lymphedema. Among women who had surgery, 31.4% were diagnosed with lymphedema after 1 year compared with 16.1% of the women who had radiotherapy.
“Both lymph node dissection and radiotherapy to the axilla provide excellent and comparable locoregional control in sentinel node positive breast cancer patients after 10 years,” Rutgers said. “There is significantly less lymphedema after radiotherapy after 5 years. Axillary radiation therapy can be considered standard procedure.”
For the study, the researchers enrolled women who had been diagnosed with T1-T2 breast cancer and were going to undergo sentinel node biopsy. Patients had no clinical evidence of local spread of disease to the axillary lymph.
“Traditionally, those patients who had cancer detected in a sentinel lymph node biopsy underwent axillary lymph node dissection, which is an effective but invasive surgical procedure that is associated with adverse side effects such as lymphedema and difficulties moving the arm,” he said.
The researchers assigned 598 women to undergo the surgical procedure if the sentinel node biopsy proved positive and 535 women to receive radiation therapy instead.
Rutgers told MedPage Today that about 10% of each group opted out of their assigned study arm when their sentinel node biopsy results became known.
He said that 5 years ago when the results were similar, the uptake among the medical community for radiotherapy for these patients was not rapid; hence, the 10-year follow-up was completed in hopes of bolstering the case for radiation. While accepted in the Netherlands, there is still reluctance to only perform radiation in Europe and North America for women with positive sentinel nodes.
In commenting on the study, SABCS press conference moderator Virginia Kaklamani, MD, of the University of Texas Health San Antonio, told MedPage Today, “When you have a positive lymph node, intuitively you want to clear this disease, and in this study one-third of the women who had a positive sentinel node also had positive lymph nodes — yet they did not benefit from surgery over radiation.”
“That leads us to believe that we can de-escalate therapy, and we can offer radiation instead of axillary dissection,” Kaklamani added. She said that after 5 years the results were questioned due to a short period of follow-up.
“But with this study, out to 10 years, I think we can be confident of these results,” she said. “The benefit of de-escalating therapy is that you are helping the patients have a better quality of life by decreasing the morbidity of the treatment. With axillary dissection, patients have a higher probability of lymphedema — as high as 30%, whereas with radiation, that risk is now 14% to 15%, cutting the risk by half.”
Rutgers and Kaklamani disclosed no relevant relationships with industry.