Pathological and molecular assessment of sentinel lymph nodes in solid tumors.

Sentinel nodes (SNs) are the first set of nodes to receive drainage and cancer cells from a primary tumor. While there may be a single SN, frequently there are one to three or more SNs. The development of sentinel node surgery over the last decade has led to dramatic changes in the surgical approach to regional nodes draining solid tumors. The surgeon can now identify, to a level of accuracy previously impossible, the regional nodes most likely to be involved with cancer in any individual patient. This new capability comes at a cost; the principles guiding the extent of nodal surgery must be completely re-examined. The extent of surgical resection required to achieve each of the goals of regional node surgery-(1) establishing prognosis, (2) obtaining regional control, and (3) improving overall survival-may no longer be simply the default "regional node resection" and may vary depending on the clinical goals. Inseparable from this new surgical technology is the methodology employed for pathologic evaluation of SNs. It is critical that pathologists and clinicians conduct definitive clinical research directed toward defining the role and impact that SN surgery has on each of these surgical goals.