When to Use Sentinel Lymph Node Biopsy in Early Breast Ca - Brief Article

Family Pratice News,  May 1, 2000  by Bruce Jancin

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SAN ANTONIO -- Surgeons are trying to pin down which women with early-stage breast cancer should undergo sentinel lymph node biopsy and who ought to be performing it.

Breast cancer patients are clamoring for sentinel lymph node biopsy, a favored procedure because of its potential to reduce morbidity, compared with standard axillary dissection. Women with a negative sentinel node--the first in the lymphatic chain draining away from the tumor site--can be spared a full nodal dissection on the grounds that if that node is not affected, none are.

But the procedure clearly is not for everyone, Dr. Peter Ng reported at a breast cancer symposium sponsored by the San Antonio Cancer Institute.

Specifically a new multicenter prospective study has demonstrated that the sentinel lymph node (SLN) biopsy failure rate is more than threefold higher in patients over age 50 than in younger patients, said Dr. Ng of East Carolina University in Greenville, N.C.

Moreover, the failure rate, defined as a false-negative result or inability to identify an SLN, also tended to be higher in women with a medial tumor location than in those with a central or outer-quadrant tumor.

"We recommend that surgeons use discretion in applying this technique to older candidates and patients with medial tumors," he concluded.

There is also broad consensus that SLN biopsy is inappropriate in patients with palpable axillary nodes or multiple primary tumors.

Dr. Ng reported on 485 breast cancer patients who underwent SLN biopsy followed by confirmatory axillary node dissection. None of the 41 participating surgeons had prior SLN biopsy experience.

Subsequent complete axillary dissection showed that SLN biopsy results were falsely negative in 18 patients. There were another 65 instances of surgeon inability to identify an SLN. Of note was the 15.4% failure rate in women age 50 or older, compared with just 5.1% in younger patients.

Also of note: Surgeons who contributed 11 or more cases to the study had a failure rate of 8.2%, compared with 17.9% for those with 10 or fewer cases.

This finding that success in SLN biopsy is heavily dependent upon surgical experience has been noted by others. Indeed, an American College of Surgeons consensus statement recommends that a surgeon do at least 30 SLN biopsies while achieving a false-negative rate of less than 5% before abandoning complete axillary dissection.

"We concur with this recommendation," said Dr. Ng, noting that the few surgeons in the study who contributed more than 30 cases had an extremely low procedural failure rate.

In a separate presentation, Dr. William C. Wood observed that when surgeons at New York's Memorial Sloan-Kettering Cancer Center reviewed their collective experience with SLN biopsy they found their false-negative rate exceeded 10%; but the rate was cut in half when they excluded each surgeon's first six cases.

Many general surgeons view the ACS's recommended 30-biopsy learning curve as too tough. Patient demand for the procedure has persuaded some surgeons to scrap the experience-building process altogether. Instead, they go to a workshop, view some slides on SLN biopsy then start offering the procedure as an alternative to conventional axillary dissection.

Recent discussions among representatives of surgical societies are leaning toward making a new recommendation that surgeons interested in SLN biopsy first observe a colleague who is proficient in the procedure, then do a minimum of 20 rather than 30 SLN mappings backed by complete axillary node dissection.

"If a person can identify 18 of 20 sentinel lymph nodes at a minimum with no more than one false negative in that series in all the axillary dissections, it may well be appropriate to stop doing axillary dissection," said Dr. Wood, the Joseph Brown Whitehead Professor and chair of surgery at Emory University in Atlanta. This is a lot for the average general surgeon in a community hospital, he conceded.

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