Eight false negative sentinel node procedures in breast cancer: what went wrong?

Aims: The purpose of the study was to evaluate the false negative sentinel node procedures in patients with breast cancer at our institution. Methods: A total of 606 sentinel node biopsies were performed on 599 clinical N0 breast cancer patients between January 1997 and November 2001. Results: The axillary sentinel node revealed metastasis in 204 (36.1%) of the 565 patients in whom it was identified and was false negative in eight patients. Two false negative results came to light by confirmatory axillary lymph node dissection during the learning phase. Tumour-positive lymph nodes were incidentally found in the axillary tail of the simple mastectomy specimen in two patients. Excision of a firm, non-radioactive, unstained but tumour-positive non-sentinel node occurred in three other patients. One patient developed an axillary recurrence 22 months postoperatively. Presumptive causes were surgical delay, pathological sampling error and tumour blocking. Conclusion: Intra-operative palpation of the axilla to identify suspicious lymph nodes is recommended. In a two-day protocol, surgery should be performed first thing in the morning. Seven slices of 50–150-μm strike an acceptable balance between sensitivity and work load for the pathologist.