Sentinel Lymph Node Biopsy Useful After Neoadjuvant Chemotherapy

ORLANDO—The concept of sentinel lymph node biopsy as an alternative to axillary node dissection appears to be applicable and useful in breast cancer patients after neoadjuvant chemotherapy, according to an analysis from protocol B-27 of the National Surgical Adjuvant Breast and Bowel Project (NSABP), presented at the 38th Annual Meeting of the American Society of Clinical Oncology (abstract 140).

These results are comparable to those obtained from studies evaluating sentinel node biopsy before systemic therapy and therefore provide encouragement that this procedure can be applied earlier in the management process, the NSABP investigators noted.

The results from the primary analysis of B-27 were reported at the 2001 San Antonio Breast Cancer Symposium. At ASCO, Terry Mamounas, MD, MPH, presented an updated analysis that linked tumor response data to sentinel node biopsy results. Dr. Mamounas is associate professor of surgery, Northeastern Ohio University College of Medicine, Canton.

NSABP B-27 evaluated neoadjuvant Adriamycin/cyclophosphamide (AC) (60/600 mg/m² every 3 weeks) plus docetaxel (Taxotere) (100 mg/m² every 3 weeks) in 2,411 patients with large operable tumors. Patients were randomized to four cycles of AC followed by surgery, four cycles of AC followed by four cycles of docetaxel and then surgery, or four cycles of AC, then surgery, followed by four cycles of docetaxel.

Dr. Mamounas reported on a subset of 428 patients who underwent sentinel node biopsy off protocol at the discretion of their physicians. At least one sentinel node was identified and removed in 363 of these patients, for an 85% identification rate. Identification was not related to the year the procedure was performed, or the age, tumor size, or nodal status of the patient, and was most successful when radioisotope was used.

In 343 patients, both sentinel node biopsy and axillary nodal dissections were performed, providing an opportunity to assess the effectiveness of sentinel node biopsy after neoadjuvant therapy.

The sentinel node was positive in 125 patients, and it was the only positive node in 70 patients (56%), Dr. Mamounas said. The sentinel node was negative in 218 patients, and it was falsely negative in 15 of 140 node-positive patients (11%) or 4% of all patients (15 of 343).

"Sentinel lymph node biopsy accurately predicted axillary nodal status in 96% of all patients, and in 89% of all node-positive patients. The overall false-negative rate was 11%," Dr. Mamounas reported. "This rate is similar to other published multicenter trials of sentinel biopsy after breast cancer diagnosis."

The study also examined the false-negative rate for sentinel node biopsy according to tumor response. There was no significant association between the sentinel biopsy false-negative rate and clinical characteristics or tumor response to neoadjuvant chemotherapy. Since patients with a pathologic complete response had the lowest incidence of positive axillary nodes (13%), the error rate with the sentinel biopsy was also the lowest (1.8%) in this group of patients.

"Since these rates are comparable to those obtained by sentinel node biopsy before systemic therapy, they are encouraging and suggest that the sentinel node concept may be applicable in patients who get neoadjuvant chemotherapy," Dr. Mamounas concluded.