Prognostic false-positivity of the sentinel node in melanoma.

It is a basic tenet of the sentinel lymph-node biopsy procedure that all positive sentinel lymph nodes will inevitably progress to palpable nodal recurrence if not removed. Comparison of survival is, therefore, considered permissible among patients with positive sentinel lymph nodes who undergo early lymphadenectomy with that among patients who have delayed lymphadenectomy for palpable regional node metastasis, providing that survival is calculated from the date of wide local excision of the primary tumor. Here, that fundamental assumption is contested and evidence is presented to show that a positive sentinel lymph node might have no adverse prognostic relevance in up to one-third of patients. Furthermore, in the same patients, progression to palpable nodal disease might not have occurred even if the positive sentinel node had not been removed. The term prognostic false-positivity is used to describe this phenomenon. Such patients are incorrectly up-staged, are given inaccurate prognostic information and can undergo unnecessary completion lymphadenectomy and unnecessary adjuvant therapy.