Detection of occult melanoma cells in sentinel lymph nodes and blood

The presence or absence of regional nodal metastases is the most important prognostic factor for predicting survival in patients with clinical stage I or II cutaneous melanoma. Successful treatment of melanoma patients with primary tumors greater than 0.76-mm thick without clinically palpable nodes is thus critically dependent on identification and biopsy of the sentinel lymph nodes and the detection of possible occult micrometastases in those nodes. Biopsy of sentinel lymph nodes has been greatly facilitated by the development of lymphoscintigraphy. Immunohistochemical and polymerase chainreaction (PCR)-based detection of unique melanoma markers have also dramatically improved our ability to detect nodal micrometastases and assess the risk of recurrence in this patient population. These techniques now make it possible to perform complete lymph node dissection only in those patients with confirmed nodal metastases. The detection of occult melanoma cells in blood using a sensitive multimarker PCR assay is also contributing to the proper staging of melanoma. These techniques have greatly enhanced the oncologist's ability to make rational treatment decisions.