Update on detection of sentinel lymph nodes in patients with breast cancer.

Sentinel lymph node biopsy is now the practice of choice for the management of many patients with breast cancer. This was not true in the early 1990s, when the first such procedures were performed and protocols for such were refined often. This was also not true in the first years of the 21st century, when a decade of collective experience and information acquired from numerous clinical investigations dictated additional subtle and not-so-subtle refinements of the procedures. However, it is true today; reports of the latest round of clinical investigations indicate that there are several breast cancer sentinel node procedures that result in successful identification of potential sentinel nodes in nearly all patients who are eligible for such procedures. A significant component of many of these successful sentinel node procedures is a detection and localization protocol that involves radiotracer methodologies, including radiopharmaceutical administration, preoperative nuclear medicine imaging, and intraoperative gamma counting. The present state and roles of nuclear medicine protocols used in breast cancer sentinel lymph node biopsy procedures is reviewed with emphasis on discussion of recent results, unresolved issues, and future considerations. Included are brief reviews of present radiotracer and blue-dye techniques for node localization, including remarks about injection strategies, counting probe technology, and radiation safety. Included also are discussions of on-going investigations of the implications of the presence of micrometastases; of the management value of detection, localization, and excision of extra-axillary nodes such as internal mammary nodes; and of the broad range of recurrence rates presently being reported. Remarks on the present and possible near- and long-term roles for nuclear medicine in the staging of breast cancer patients including comments on positron emission tomography and intraoperative imaging conclude the article.