Regression and Sentinel Lymph Node Positivity

Summary and Comment |
January 14, 2016

Regression and Sentinel Lymph Node Positivity

  1. Hensin Tsao, MD, PhD

Histologic regression was a marker of lower risk for SLN positivity and could inform identification of patients needing biopsy.

  1. Hensin Tsao, MD, PhD

Sentinel lymph node (SLN) biopsies remain one of the best predictors of outcome for melanoma. Although the procedure itself is relatively benign, the completion lymphadenectomy in the event of a positive node can be highly morbid. If there were better predictors of positivity, some individuals might be spared unnecessary surgery.

Tumor regression may affect prognosis, because disappearance of neoplastic cells may cause an underestimation of the initial Breslow thickness, making a sentinel lymph node biopsy (SLNB) inaccurate. Conflicting research findings have suggested that regression heightens and lowers risk for SLN metastasis, and that it has no effect on metastasis or prognosis. Without clear guidelines, selection criteria for SLNB vary widely between institutions and countries. These researchers conducted a meta-analysis to determine the incidence of SLN positivity in patients with histologic regression in primary melanoma tumors. In 14 studies covering 10,098 patients, those with regression had a lower likelihood of SLN positivity (odds ratio, 0.56; 95% confidence interval, 0.41–0.77) than patients without regression.

Comment

Histologic regression has been a somewhat controversial prognostic marker. On the one hand, the presence of regression suggests effective immune surveillance and thus a potentially better outcome. On the other hand, the loss of tumor thickness may underestimate the true biologic depth of the melanoma. In this review, regression appears to be associated with a lower risk for nodal involvement. However, as the authors indicate, the studies are highly heterogeneous. Moreover, there is no survival data downstream of the nodal prediction. The ongoing MSLT-2 trial addresses the exact question of whether completion lymphadenectomy is required after the initial sentinel positivity, but has not posted results. Nevertheless, in borderline cases, the presence of tumor regression may tip the scale against performing the procedure.

Editor Disclosures at Time of Publication

  • Disclosures for Hensin Tsao, MD, PhD at time of publication Consultant / advisory board Lubax; WorldCare Clinical Equity Lubax Grant / Research support NIH; Department of Defense; American Skin Association; Piramal Editorial boards British Journal of Dermatology; Journal of the American Academy of Dermatology; Journal of Investigative Dermatology Leadership positions in professional societies American Academy of Dermatology (Chair, Skin Cancer and Melanoma Committee); American Board of Dermatology (Director)

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