Regression of Melanoma Not Linked to Sentinel Node Positivity

Current research has differing conclusions about the influence of regression of melanoma on the prognosis of the patient.

The presence of regression in melanomas with a Breslow thickness greater than 0.75 mm does not appear to be linked to a higher likelihood of sentinel node involvement, according to the results of a retrospective study published in JAMA Dermatology.

“When primary melanomas were stratified according to Breslow thickness, some differences in the percentage of sentinel node positivity between melanomas with or without regression appeared, but they were not statistically significant,” wrote Rafael Botella-Estrada, MD, PhD, of the Instituto Valenciano de Oncologia, and colleagues.

In fact, the results suggested that those melanomas with regression had a lower frequency of sentinel node involvement.

Current research has differing conclusions about the influence of regression of melanoma on the prognosis of the patient, with some concluding that it increases the likelihood of metastasis and others indicating that it may be a prognostic factor.

“The interpretation given for the poor prognosis associated with regression is that the disappearance of a portion of the tumor may lead, at least in some cases, to an underestimation of the original Breslow thickness,” the researchers wrote. “For this reason, in many hospitals, thin melanomas (< 1 mm) with histologic features of regression are considered candidates for sentinel node biopsy.”

In this study, Botella-Estrada and colleagues wanted to establish if there was a link between tumor regression and sentinel node status. The study included melanomas from 201 patients. All melanomas had a Breslow thickness of 0.75 mm or greater and patients had undergone sentinel node biopsy between 2003 and 2010 at the Instituto Valenciano de Oncologia.

Sentinel node positivity was identified in 19.9% of cases, and all but one patient underwent lymphadenectomy. Regression was identified in 25.9% of cases (52 melanomas). No statistically significant association between regression and sentinel node status was found.

“Nevertheless, a higher percentage of positive sentinel nodes were found when regression was absent,” the researchers wrote.

The researchers divided the melanomas by Breslow thickness. The data showed that melanomas with a Breslow thickness of less than 1 mm, 1.01 mm to 2 mm, or greater than 4 mm had a lower frequency of positive sentinel nodes.

An axial location of the primary melanoma had a statistically significant association with regression compared with location on the extremities (P < .001).

The researchers also found that the percentage of melanomas with regression was high in the group with a Breslow thickness of 1 mm or less and was low in those melanomas with a thickness greater than 4 mm.

“The present data support the conclusion that regression should not have any influence in melanomas of 0.75 mm or less because regression did not influence melanomas in the next thickness groups,” the researchers wrote. “Therefore, the presence of regression does not justify the performance of a sentinel node biopsy in melanoma.”