Women with invasive breast cancer who were treated with axillary lymph node dissection saw no survival benefit over 10 years compared to those who received sentinel lymph node dissection, a less aggressive procedure, according to a clinical trial recently published in JAMA.
Dr. Nora Hansen, chief of breast surgery in the department of surgery at Northwestern Medicine, was a co-author of the study.
When cancer is found to have spread to the sentinel lymph node — the closest node to the tumor — patients with breast cancer sometimes also receive an axillary lymph node dissection (ALND), where the majority of lymph nodes in the nearby underarm region are also removed.
A less invasive procedure, sentinel lymph node dissection (SLND), removes only the first key lymph nodes.
Previously, ALND was generally considered to be necessary for controlling cancer in the region. But there are also significant complications associated with the procedure, including numbness and lymphedema, where lymphatic system blockage causes painful swelling in the arms and legs.
In the current clinical trial, investigators sought to determine whether ALND in fact led to better survival outcomes, compared to SNLD alone, in patients with invasive breast cancer that had metastasized to one or two sentinel lymph nodes, but no more.
The trial participants included more than 800 women who were all treated with lumpectomy, adjuvant radiation and chemotherapy. They were randomized to receive either SNLD alone, or SNLD with ALND.
The initial results of the trial, published in 2005, showed that the overall survival in women who received SLND alone was no worse than those who also underwent ALND, over a median follow-up of 6.3 years. Disease-free survival rates were also similar.
But the results remained controversial, given the relatively short follow-up time of the study. Some argued that additional follow-up was needed, especially since the majority of patients in the trial had hormone receptor-positive breast cancer, a form of the cancer with a long natural history and significant risk of relapse after five years.
In the current JAMA paper, the investigators extended the follow-up from the initial trial to a median of 9.3 years and saw similar results: overall survival rates were no worse in the SLND group than in the group who also received ALND.
According to the study, the findings do not support the use of axillary lymph node dissection in this particular group of breast cancer patients — who have one or two positive nodes — given the lack of survival benefit and the increased risk of complications.
The trial, called the American College of Surgeons Oncology Group Z0011 (ACOSOG ZOO11), was supported by National Cancer Institute grants U10CA180821, U10CA180882, U10CA047559, U10CA077651, U10CA180791, U10CA180838, U10CA180858, and U10CA180870.