Evaluation of incomplete sentinel node biopsy procedures and sentinel node positivity rates as surgical quality-assurance parameters in melanoma patients.

Background: There is little literature describing quality assurance (QA) validation of an individual surgeon's ability to perform sentinel node biopsy (SNB) in melanoma patients. This study aims to evaluate incomplete SNB rates and SNB positivity rates as potential QA parameters.

Methods: An institutional database identified 2,874 patients with primary melanoma who had SNB performed when there was lymphoscintigraphy drainage to a single lymphatic field. Lymphoscintigraphy data were obtained from another database. Lymphoscintigraphy utilized small-particle colloid, allowing visualization of channels entering sentinel nodes on early dynamic scanning. Incomplete SNB was defined as retrieval of fewer sentinel nodes than identified on lymphoscintigraphy.

Results: The overall rate of incomplete SNB was 17.7 % (including axilla 7.8 %, neck 23.3 %, and groin 28.8 %). Individual surgeons varied significantly in their proportion of SNBs performed in each region (p < 0.001). The surgeons' overall incomplete SNB rate varied significantly (p < 0.001). The surgeons' incomplete SNB rate in the axilla ranged 3-16 % (p < 0.001), median 6 %; groin 21-41 % (p = 0.002), median 26 %; and neck 19-43 % (p = 0.374), median 22 %. The respective axillary, groin, and neck SNB positivity rate for incomplete SNB patients were 10, 23, and 18 % compared to "complete" SNB patients 14, 19, and 14 %. There were no significant differences between surgeons' SNB positivity rates.

Conclusions: Incomplete SNB rates vary between surgeons in each region. SNB positivity rates do not vary commensurate with the incomplete SNB rates. The ranges described could be used as QA parameters, however because none of these experienced surgeons are outliers, the robustness of these parameters remains unproven.