Sentinel Lymph Node Biopsy for Breast Cancer: Will Variations in Technique Influence Long-Term Outcome?

Lymphatic mapping was introduced to the medical community as an addition to the armamentarium of breast cancer management strategies just over a decade ago. The biological plausibility of sentinel node biopsy is based on the rationale that we can replicate the pathway that would be traversed by cancer cells from a primary breast tumor through intramammary lymphatic channels en route to implantation in the first nodal recipients of metastasis. Early studies involved sentinel lymphadenectomy performed with a concomitant axillary lymph node dissection (ALND) so that accuracy rates could be defined. Within the following 5 years, identification rates in excess of 95% and false-negative rates of <5% were being consistently reported by numerous investigators internationally. These promising results led to the acceptance of a cancer-free sentinel lymph node as a reliable means of identifying the node-negative patient who could be spared the morbidity of a standard ALND. In this issue of Annals of Surgical Oncology, two reports serve as reminders that while we continue to search for ways that we can revise and improve sentinel node biopsy algorithms, we must remember the ultimate goals of axillary surgery in breast cancer patients: the accurate determination of nodal status for prognostic value and regional control of disease. In the studies reported herein, Degnim et al. have systematically evaluated whether selected patients can avoid the allergenic risks of blue dye mapping, and Fan et al. have looked at their institution s outcome experience after sentinel lymphadenectomy. Initial mapping experiences included rigorous attention to technical and anatomical details. The blue dye and/or radioactive label was injected peritumorally, and after waiting some prespecified interval, the patient would undergo axillary exploration. Blue dyes were injected during surgery, approximately 5 minutes before sentinel node dissection. Radioactive isotopes were injected peritumorally, and the timing of the surgery was based on subsequent lymphoscintigraphy, which was frequently performed on a sequential basis until sentinel uptake was identified on a preoperative scan. These techniques were mechanistically sound; however, they became logistically burdensome as the volume of mapping cases increased. Patients with nonpalpable tumors frequently required additional image-guided localization procedures to facilitate injection of the mapping label, and surgical schedules were disrupted by the unpredictability of lymphoscintigraphy results: uptake in a nodal basin might occur within 30 minutes, or it might require several hours. It was therefore inevitable that variations in technique would be explored to improve the efficiency and ease of incorporating lymphatic mapping cases into busy operating room caseloads. Some of the first variations in mapping technique involved alternative injection sites, such as dermal injections overlying the breast tumor or subareoReceived May 23, 2005; accepted June 9, 2005; published online August 4, 2005. Address correspondence and reprint requests to: Lisa A. Newman, MD, MPH; E-mail: lanewman@umich.edu.