Some Women May Not Need More Extensive Lymph Node Surgery for Breast Cancer
Clinical trials have shown that surgeons can remove less tissue from women who have early-stage, lymph node-negative breast cancer without increasing their chances of the disease returning or affecting their overall survival. Now, a study led by Dr. Armando Giuliano of the John Wayne Cancer Institute in Santa Monica, CA, adds to that knowledge by demonstrating that a surgical practice called axillary lymph node dissection (ALND) isn’t necessary for some women with early-stage disease when cancer cells are found in the adjacent lymph nodes. The study was published February 9 in JAMA.
In this randomized phase III clinical trial, called ACOSOG Z0011, women with early-stage breast cancer who underwent sentinel lymph node biopsy (SLNB)—the removal of one or two lymph nodes in the armpit to test for the presence of cancer cells—and whose sentinel nodes were positive for cancer, lived just as long as women who had SLNB followed by ALND—the removal of many lymph nodes from under the arm. Most of the women in the trial also received systemic therapy (hormone therapy, chemotherapy, or both) in addition to radiation therapy to the whole breast.
“These results support the use of SLNB alone in selected women with one or two positive sentinel lymph nodes, and could potentially spare thousands of women the side effects of a full axillary lymph node dissection,” commented Dr. Jo Anne Zujewski, head of Breast Cancer Therapeutics in NCI’s Division of Cancer Treatment and Diagnosis.
The findings are limited to a specific population of women, noted Dr. Eric Winer of Harvard Medical School, who also was not involved with the study. “Doctors…must be very cautious about applying these results to patients who would not have been eligible for this trial,” Dr. Winer said. Women who were not eligible included those with palpable axillary lymph nodes, women who had breast tumors larger than 5 cm in diameter, women with three or more positive sentinel lymph nodes, women who received chemotherapy or hormone therapy before surgery, and women who underwent mastectomy instead of breast-conserving surgery with radiation.
Radical mastectomy for breast cancer, pioneered in the 1880s, provided the first surgical treatment for this disease, but at great expense to quality of life: the deforming surgery removed large amounts of tissue, including the breast, the underlying chest muscles, and all of the lymph nodes under the arm, and left women with extensive life-long side effects, including pain and lymphedema.
Today, most women with early-stage breast cancer undergo breast-conserving surgery followed by radiation therapy in lieu of mastectomy, while women with more advanced disease can be treated with a modified radical mastectomy.
“Patients would like to avoid more radical surgery,” said Dr. Giuliano. “They’ve already seen with lumpectomy how less surgery can be as effective.”
Half of the women enrolled in this study were randomly assigned to SLNB followed by ALND and the other half to SLNB alone. Women in the ALND group had a median of 17 axillary lymph nodes removed, compared with a median of two in the SLNB-alone group. All women underwent breast-conserving surgery and received whole-breast radiation therapy. The use of adjuvant chemotherapy and hormone therapy was determined individually for each woman.
After a median of more than 6 years, the 5-year overall survival rate was 91.8 percent in the ALND group and 92.5 percent in the SLNB-alone group. Rates of disease recurrence were also virtually equal between the groups.
“What surgery and radiation do—what local therapy does—is provide local control of the cancer,” explained Dr. Giuliano. Local control means preventing the cancer from returning in the breast or nearby tissue. “Failure to have local control could impact survival, but we had such high local control rates [in both arms of this trial] that I think it’s unlikely that we will see a difference in survival over time.”
Importantly, almost all women in both arms of the trial received some kind of systemic treatment. “In an era when virtually all women receive some form of systemic therapy, this study would suggest that removing additional lymph nodes after sentinel node biopsy is not of further benefit,” said Dr. Winer. “We don’t know whether this result would have been seen in the absence of systemic therapy, but I think it’s a reasonable hypothesis that there could have been a difference,” he explained, since systemic therapies kill cancer cells throughout the body, including in the lymph nodes.
Rates of negative side effects from surgery were much higher in the ALND group, with 70 percent of women experiencing wound infection, delayed healing, or pain compared with 25 percent of women in the SLNB-alone group. Lymphedema was also reported by more women in the ALND group. (The researchers reported complete data on side effects seen during the trial in a previous paper.)
The results from ACOSOG Z0011, wrote Drs. Grant Walter Carlson and William Wood of the Winship Cancer Institute at Emory University in an accompanying JAMA editorial, are a “testament” to the overall improvements made in breast cancer treatment since the early 1970s, when the first large clinical trial testing less-invasive surgery for breast cancer began. At the time of that trial, only about 60 percent of women were living 5 years after diagnosis, compared with more than 90 percent of women in the current trial.
Women eligible for the study were recruited from 115 hospitals across the country, had an invasive breast tumor of 5 cm or less in size, no obviously swollen lymph nodes, and cancer cells in no more than two nearby nodes as detected by SLNB.
The researchers had planned to enroll 1,900 women in the trial. However, survival rates were so high in both study arms that the independent data and safety monitoring committee recommended closing enrollment after only 891 women had joined the study because the researchers were unlikely to observe enough deaths to ever discern a difference in overall survival between the groups, even after 20 years.
Dr. Winer urged some caution in declaring the results definitive, because the trial could not meet its planned accrual goals due to excellent overall survival. “But I don’t think we’re going to get better data than this,” he said. “Given these results, and given the reluctance of some surgeons and some patients to undergo axillary lymph node dissections based on these results, it would be almost impossible to mount another randomized trial in this same patient population.
“However, I do think there is room for clinical trials in somewhat different patient populations,” he continued, “since this study was only in women who underwent conservative surgery and radiation.”
For the thousands of women diagnosed with breast cancer each year whose disease fits the trial’s enrollment criteria, ALND may be a thing of the past for now. “Women with breast cancer should discuss all their options with their physician,” concluded Dr. Giuliano. “They may not need as radical an operation as they once believed.”