Final results of the Department of Defense multicenter breast lymphatic mapping trial

Lymphatic mapping and sentinel lymph node (SLN) biopsy have the potential to become the standard of care for nodal staging in breast cancer patients, but their widespread utility outside of university-based centers has not been determined. This study describes the final results from a national multi-institutional trial designed to determine the role of preoperative lymphoscintigraphy in breast lymphatic mapping, the rate of success for finding an SLN, and the rate of skip metastasis for patients with invasive breast cancer across all practice scenarios.

Lymphatic mapping techniques involving the combined use of blue dye and radiocolloid were taught to participating surgeons through a formal 2-day training course at the Moffitt Cancer Center. In protocol 1, surgeons performed their first 20 to 25 cases of breast mapping with SLN biopsy followed by complete axillary lymph node dissection. In protocol 2, after the learning phase, surgeons did not perform axillary lymph node dissection unless a SLN was positive for metastatic disease.

Forty-two institutions, including 12 university-based research centers, participated in the trial. From July 1, 1997, through January 31, 1999, a total of 965 patients were accrued. Lymphoscintigraphy identified drainage to an axillary SLN 64% of the time, but by using sensitive handheld gamma probes at the time of the operation, an axillary SLN could be identified 86% of the time. The rate of success for finding an axillary SLN was 92.8% for cases performed at the Moffitt Cancer Center. For other university centers, the rate of success of identifying an axillary SLN was 91.4%, and for other community/regional hospitals in the study, it was 85.2%. For cases in which protocol 1 was followed, the rate of false-negative SLN biopsy was 4%. There was no axillary nodal recurrence after a negative SLN in protocol 2 when a negative SLN biopsy was followed by observation. The median follow-up for the patients on protocol 2 was 16 months.

These data show a high rate of success for finding an axillary SLN and a low rate of skip metastasis in a national multicenter study of lymphatic mapping for breast cancer. This study suggests that SLN biopsy for breast cancer can be performed successfully in community/regional hospitals, as well as in major university-based centers.