Histologic regression may predict SLNB benefit in melanoma
Sentinel lymph node positivity occurred less frequently in patients with primary melanoma who had histologic regression, according to the results of a systemic review and meta-analysis.
Histologic regression may, thus, serve as a prognostic indicator for selecting which patients should undergo sentinel lymph node biopsy, according to the researchers.
“Histologic regression in melanoma is defined as an area within the tumor in which neoplastic cells have disappeared or become reduced in number from the dermis (and occasionally from the epidermis) and have been substituted by fibrosis with accompanying melanophages, new vessels and a variable inflammatory infiltrate,” Simone Ribero, MD, PhD, of the dermatology section of the department of medical sciences at University of Turin in Italy, and colleagues wrote. “The prognostic significance of regression in primary melanoma has been debated for many years.”
No consensus exists regarding the need for sentinel lymph node biopsy (SLNB) when regression is present within the primary tumor, according to the researchers.
Ribero and colleagues sought to review the evidence that regression may affect sentinel lymph node status. Researchers searched MEDLINE, Scopus and the Cochrane Library between 1990 and 2014 and selected all studies that reported an OR, or data on expected and observed cases of sentinel lymph node positivity and histologic regression.
Of 94 studies reviewed, the researchers included 14 studies — composed of 10,098 patients — in their final analysis.
Based on data from these studies, the researchers observed that patients with histologic regression had a lower likelihood to have sentinel lymph node positivity compared with patients without regression (OR = 0.56; 95% CI, 0.41-0.77).
Researchers also conducted an analysis based on study quality. Results showed patients enrolled in high-quality studies had a lower likelihood to have sentinel lymph node positivity (OR = 0.48; 95% CI, 0.32-0.72) compared with the results of low-quality studies (OR = 0.73; 95% CI, 0.53-1).
The researchers constructed a funnel plot, which showed no evidence of publication bias.
The researchers acknowledged significant heterogeneity among studies and the potential for different definitions of histologic regression between studies as limitations.
“The results of this meta-analysis may be useful when deciding to offer SLNB to patients with regressions of melanomas,” Ribero and colleagues wrote. “It may help clinicians make a final selection of the most appropriate patients for this procedure.”
More information is needed to determine a standard of care regarding SLNB in patients with primary melanoma, Claus Garbe, MD, professor of dermatology at Eberhard Karls University in Germany, wrote in an accompanying editorial.
“These findings underline that fact that prognosis of patients with melanoma does not depend only on the characteristics of the tumor itself, such as tumor thickness, ulceration, and mitosis, but also on the immune response of the host,” Garbe wrote. “It has been shown that tumor-directed T-cell responses are a favorable sign for the outcome of patients with metastatic melanoma independently of the kind of treatment. Unfortunately, we do not yet understand which immunologic markers can guide us in making therapeutic decisions related to tumor-specific immune responses. There is still a great unmet medical need for understanding the interaction of the immune system and solid tumors.” – by Cameron Kelsall
Disclosure: The researchers report no relevant financial disclosures. Garbe reports no relevant financial disclosures.