Comparative analysis of histological predictors of adverse course of anorectal melanoma and skin melanoma

Aim. Analysis of the effect of histological characteristics on the prognosis of anorectal melanoma (ARM) and melanoma of the skin.

Materials and methods. The study is based on a retrospective single-center analysis of the results of treatment of two groups of patients: with ARM and cutaneous melanoma. N.N. Blokhin National Medical Research Center of Oncology in the period from 2005 to 2023 regarding ARM, were taken from the archives of the pathology department. In turn, a group of patients with cutaneous melanoma was recruited from the «Melanoma Pro» registry. Patients were matched by age, gender and stage of the disease. Disseminated patients were excluded from both groups. A univariate and multivariate analysis of the influence on relapse-free survival and overall survival (OS) of the main clinical characteristics, as well as selected histological prognostic markers of skin melanoma was carried out: multifocal growth, maximum tumor size, maximum Breslow thickness, presence or absence of ulceration, neurotropism and lymphovascular invasion, and depth of invasion (layer).

Results. The study included 21 patients in each group with ARM and skin melanoma. The skin melanoma group included: stage I–II – 9 (42.9 %); stage III – 12 (57.1 %). Data on lymphovascular invasion were available in 68 patients (of which 15 (22.1 %) showed it, p = 0.03), on ulceration – in 428 patients (of which 207 (48.4 %) had it, p = 0.00001), on neurotropism – in 57 patients (of which 3 (5.3 %) showed it, p = 0.35). In the ARM group, there was a tendency for the influence of Breslow invasion of more than 20 mm (hazard ratio 1.028, 95 % confidence interval 0.998–1.060, p = 0.070) and the level of tumor invasion (layer) (hazard ratio 2.117, 95 % confidence interval 0.990–4.525, p = 0.053) on OS in the univariate analysis; in the multivariate analysis, none of the results showed a significant result for OS. In the melanoma group, the prevalence of OS and relapse-free survival among women did not influence our choice. In the skin melanoma group, none of the factors had a significant effect on OS and relapse-free survival in our sample.

Conclusion. Despite the fact that the analysis of the effectiveness of using histological characteristics of skin melanoma showed their potential use as factors of adverse effect on relapse-free survival and OS in ARM, no reliable effect on prognosis was found in the skin melanoma group. Additional studies are needed.

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