Histopathologic regression of cutaneous melanoma is commonly regarded as a favorable prognostic factor, yet its practical significance in clinical settings remains a topic of debate.
“The most important histologic prognostic factors for primary cutaneous melanoma are Breslow tumor thickness and presence of ulceration. Late-stage regression is observed in 10% to 35% of melanomas and may provide further risk stratification,” wrote Nikolaus B. Wagner, MD, and colleagues.
The researchers sought to explore the prognostic relevance of regression in patients with primary cutaneous melanoma undergoing sentinel lymph node (SLN) biopsy. They also aimed to evaluate regression’s clinical implications in patients whose disease progressed to an unresectable stage necessitating systemic therapy.
The investigators conducted a retrospective analysis of patients newly diagnosed with melanoma who underwent SLN biopsy between 2010 and 2015 and had available data on histopathologic regression (n=1,179). The team examined survival outcomes and correlations between clinical variables and SLN status.
Patients with regressive melanoma exhibited favorable outcomes in terms of relapse-free (HR, 0.52; P<0.001), distant metastasis-free (HR, 0.56; P<0.001), and melanoma-specific survival (HR, 0.35; P<0.001). Regression was associated with a negative SLN (OR, 0.48; P=0.008). Among patients whose melanoma progressed to an unresectable stage, regression was linked to improved progression-free survival with immune checkpoint inhibition (HR, 0.43; P=0.031) but not with targeted therapy (HR, 1.14; P=0.73) or chemotherapy (HR, 3.65; P=0.01).
Dr. Wagner and colleagues concluded that histopathologic regression of cutaneous melanoma was linked to better prognosis in patients eligible for SLN biopsy, as well as those with unresectable disease who received systemic therapy with immune checkpoint inhibitors.
“In our opinion, presence or absence of regression could be used to improve prognostic risk stratification in patients who are candidates for SLN biopsy,” they wrote. “Moreover, our study connects regression, a histopathologic feature of the primary tumor, with favorable efficacy of immunotherapy given months to several years later, a finding that is independent of potential confounders such as Breslow tumor thickness. Based on these findings, presence or absence of regression could be considered a novel predictive marker for systemic immunotherapy.”
