Primary melanoma regression not linked to sentinel node status

Source: Healio/Hematology-Oncology, July 2014

Histologic regression in primary melanomas ?0.75 mm was not associated sentinel node involvement, according to results of a retrospective study.

he findings suggest that sentinel node biopsy in thin melanomas with regression may not be appropriate without additional adverse prognostic factors, the researchers wrote.

Rafael Botella-Estrada, MD, PhD, of the department of dermatology at the Hospital Universitario La Fe in Valencia, Spain, and colleagues evaluated data from 201 patients, all of whom had melanomas with a Breslow thickness ?0.75 mm. All patients underwent a sentinel node biopsy between 2003 and 2010.

Forty patients (19.9%) had positive sentinel node involvement. Fifty-two patients (25.9%) had melanomas with regression, 15 of which were considered early and 37 of which were considered late.

Researchers did not observe a statistically significant association between the presence of regression and positive or negative involvement of sentinel nodes (P=.17). However, among the 40 patients with sentinel node involvement, seven (17.5%) demonstrated histologic regression and 33 (82.5%) did not.

Researchers then stratified results by Breslow thickness. Among melanomas with regression, those that were ?1 mm, 1.01 mm to 2 mm, and ?4 mm demonstrated an insignificant trend toward lower sentinel node involvement, whereas melanomas with Breslow thickness of 2.01 to 4 mm thick did not.

Botella-Estrada also determined sentinel node status was not associated with type of regression (P=.53) or regression extension (P=.37).

Researchers found regression was significantly associated with thin melanomas — defined as ?1 mm (P=.02) — and melanomas located on an axial site (P?.001). Superficial spreading or lentigo maligna melanomas (P=.03) also were associated with regression.

Although results of an analysis focused on melanomas measuring 0.75 mm or less “would be of interest,” the findings of this study support the conclusion that regression should not have any influence on sentinel node metastasis in this patient population, the researchers concluded.

“The presence of regression does not justify the performance of a sentinel node biopsy in melanoma,” Botella-Estrada and colleagues wrote. “Future studies should investigate the mechanisms that underlie this phenomenon and the preferential involvement of melanomas located on the axis and the superficial spread and lentigo maligna melanoma types.”