Importance: The influence of regression on the status of the sentinel node (SN) is controversial. In many centers, the presence of regression in thin melanomas supports the performance of an SN biopsy.
Objective: To identify whether regression in primary melanoma has any influence on SN involvement.
Design, setting, and participants: Retrospective study of melanomas with a Breslow thickness greater than 0.75 mm and undergoing SN biopsy from January 1, 2003, through December 31, 2010, at Instituto Valenciano de Oncología, which receives melanoma patients from regional hospitals and dermatology practices. Only cases with paraffin blocks or histologic slides representative of the primary tumor and available for review were included in the study. Melanomas from 201 patients met these criteria and constitute the core of this study.
Exposures: Sentinel node biopsy in melanoma.
Main outcomes and measures: Presence or absence of regression in the primary melanoma, type (early vs late), and extension were correlated with the presence or absence of metastasis in the SNs. In addition, the main clinical and histologic characteristics of the primary melanoma were correlated with the status of SN and the regression features.
Results: Regression was found in 52 melanomas (25.9%). Regression did not show a statistically significant association with SN status. When melanomas were subdivided by Breslow thickness into 4 groups, those with regression had a lower frequency of positive SNs in 3 of the 4 groups (≤1.00, 1.01-2.00, and >4.00 mm), although differences did not reach statistical significance in any group. We found no influence by type of regression or its extension on the SN status. Regression was found more frequently in thin melanomas (≤1.00 mm), melanomas located on an axial site, and superficial spreading or lentigo maligna melanoma types (P = .02, P < .001, and P = .03, respectively).
Conclusions and relevance: Regression of the primary melanoma is not associated with a higher proportion of positive SNs. These data do not support the practice of performing SN biopsy in thin melanomas with regression in the absence of additional adverse prognostic characteristics.