Preoperative chemotherapy and sentinel lymphadenectomy for breast cancer

Background: Sentinel lymphadenectomy (SL) for breast cancer is becoming the standard of care for selected patients treated by experienced surgeons. One of the few contraindications for performing SL alone is prior chemotherapy (PC). There are, however, no data to support that PC interferes with the ability of the sentinel node to predict the presence of disease in the remaining axillary lymph nodes. The goal of this study was to determine the effect of PC on patients undergoing SL for breast cancer. Methods: A multicenter trial was organized in 1997 to evaluate the diagnostic accuracy of SL in patients with breast cancer. Investigators were recruited after attending a course on the technique of SL. Technetium-99 and isosulfan blue were injected into the peritumor region and a gamma probe was used to aid identification of the sentinel nodes. The only exclusion criteria for entrance into the trial were palpable or suspicious axillary lymph nodes. A total of 968 patients were enrolled in the trial. Twenty-nine patients were treated with PC and compared with 939 patients not receiving PC. Results: The overall, sentinel node identification rate for the PC patients was 93% (27 of 29) compared with 88% (822 of 939) for patients not treated with PC. There were no false negatives in those patients receiving PC compared with a 13% (25 of 193) false negative rate in those patients not receiving PC. The mean tumor size was 1.4 cm for the PC group and 0.6 cm for the remaining patients (P <0.005). The mean number of sentinel nodes found was 2.0 for the non-PC group and 2.5 for the PC group (not significant). As expected, a higher proportion of patients had positive axillary nodes in the PC group (52%, 15 of 29) compared with the remaining patients (21%, 200 of 939). Conclusion: In this small group of patients, PC did not adversely impact the false negative or identification rate. Most patients receiving chemotherapy have larger tumors and a higher chance of harboring metastatic disease but a significant group of these patients (48%) without metastases can potentially be spared an axillary node dissection.