In Node-Positive Breast Cancer, Sentinel Biopsy Could Avert ALND

Kate Johnson

December 06, 2012

SAN ANTONIO, Texas — Some women with node-positive breast cancer who receive neoadjuvant chemotherapy might not need to automatically undergo axillary lymph node dissection (ALND), according to a new study.

Instead, it might be possible for some to undergo a less invasive sentinel lymph node (SLN) biopsy, according to the results of a phase 2 American College of Surgeons Oncology Group study presented here at the 35th Annual San Antonio Breast Cancer Symposium.

That's because SLN biopsy is 91.0% accurate in detecting residual axillary disease after chemotherapy, the researchers found. However, SLN biopsy also had a false-negative rate of 12.6%.

"This false-negative rate is slightly higher than our predefined end point," noted lead researcher Judy Boughey, MD, a breast surgeon and associate professor of surgery at the Mayo Clinic in Rochester, Minnesota, during a press conference at the meeting.

However, she also reported that 2 variables further improved the false-negative rate: the use of dual-tracer mapping and the resection of 3 or more SLNs.

This axillary lymph node management strategy is ready for clinical use, said Dr. Boughey. "We'll be going back and evaluating it and incorporating it into our practice," she said.

"ALND is associated with morbidities, so the fewer women who need this procedure, the better," said Amy Cyr, MD, assistant professor of surgery in the division of endocrine and oncologic surgery at Washington University School of Medicine in St. Louis, Missouri. Dr. Cyr was not involved with the study.

"Many women are 'downstaged' during neoadjuvant therapy and have no remaining lymph node disease when they finally go to surgery. They therefore undergo ALND without any clear benefit," she explained.

"The expectation among the medical community was that SLN biopsy would be equally accurate after neoadjuvant therapy as it is before.... This study verifies that it is reliable for axillary staging (although a bit less accurate than traditionally reported)," she said.

According to Dalliah Black, MD, assistant professor of surgery in the Department of Surgical Oncology at the University of Texas M.D. Anderson Cancer Center in Houston, the implications for decreasing invasive ALND in node-positive breast cancer patients are "huge." However, "I'm sticking with standard of care and anxiously waiting to see how this folds out," she told Medscape Medical News.

Dr. Black said that it will be important to see these findings reproduced by others.

Study Details

The study involved 637 patients (median age, 49 years) with invasive breast cancer whose node-positive status was histologically or cytologically confirmed after fine-needle aspiration or core-needle biopsy of suspicious lymph nodes in the ipsilateral axilla.

All subjects were treated with neoadjuvant systemic chemotherapy at the discretion of the medical oncologist. They then underwent SLN mapping and removal followed by ALND at the time of their definitive breast surgery.

"The sentinel nodes were removed and submitted for pathological analysis.... In the same surgery, the patient underwent an axillary lymph node dissection to evaluate the remaining lymph nodes in the axilla," she explained.

The study protocol recommended dual-tracer SLN mapping with both blue dye and radiolabeled colloid, and eligibility required removal of at least 2 SLNs.

ALND analysis showed that 60% of subjects (n = 382) had residual nodal disease after chemotherapy and 40% (n = 255) became node negative. The 40% "were therefore unlikely to derive any benefit from axillary lymph node dissection. This is the group of patients in whom we would like to minimize the extent of axillary surgery," she said.

SLN analysis accurately identified nodal status in 91.2% of patients (all of the node-negative patients and 326 of the node-positive patients).

However, 56 patients who were node-positive on ALND were falsely identified as node-negative after SLN dissection.

Despite study protocol recommendations, not all subjects underwent dual-tracer mapping, and there was variation in the number of SLNs removed and analyzed, Dr. Boughey explained.

In a reanalysis that included only patients who underwent dual tracing and who had at least 3 SLNs removed, the false-negative rate improved to 10.8% and 9.0%, respectively, she noted.

Dr. Boughey said that for these patients, "we can feel pretty comfortable that the false-negative rate is clinically acceptable.... I would feel very safe incorporating it in clinical practice in those cases."

She said that work is underway to evaluate the correlation between the false-negative rate and axillary ultrasound after chemotherapy. It is hoped that this will "improve patient selection for the procedure and further lower the false-negative rate."

Dr. Black said that any decision to forgo ALND in favor of SLN biopsy will require centers to make routine surgical changes.

"For example, sometimes I don't use dual tracers, so if I am going to treat a patient like this, I need to use 2 tracers, and I need to be more diligent about removing more lymph nodes," she said.

The study authors and Dr. Black have disclosed no relevant financial relationships.

35th Annual San Antonio Breast Cancer Symposium (SABCS): Abstract S2-1. Presented December 5, 2012.

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