Regional lymph node infiltration and thick lesions are associated with poor prognosis in high-risk resected melanomas: A retrospective cohort study

Background: Acral lentiginous and mucosal melanoma that represent lesions without cumulative sun-induced damages account for 65 of melanomas among Asians but constitute only 5 in Caucasians. The distinct clinical manifestations might influence the clinical course, response to treatment, and outcomes. Factors associated with the prognosis of high-risk resected melanoma in Asians are still rarely reported. Methods: Clinical, histological determinants of non-distant metastatic melanoma patients who underwent complete resection in 2014–9 were analyzed. Results: Mucosal melanoma, nodular melanoma, and acral lentiginous melanoma accounted for 45.1, 40.2, and 14.2 of total melanoma cases (N = 82), respectively. Among cutaneous melanomas, all patients were diagnosed with Breslow's depth more than 4 mm (T4), 51 with ulceration, 95.6 with diameter more than 6 mm, 59 with lympho-vascular invasion, and 74 with regional lymph node infiltration. In mucosal melanomas, 78.3 were diagnosed in advanced stages, 14.5 with regional spread to lymph nodes and 77 with regional infiltration beyond mucosa. Lesions with ulceration were associated with higher risk of distant metastasis (OR 3.003, 95CI:1.01–9.09). Infiltration into regional lymph node was associated with shorter overall survival (median survivals were 17 vs 23.4 months, Mantel-Cox test P = 0.049). Patients diagnosed at Breslow T4 were also associated with poorer overall survival than T1-3 (median survivals were 23 vs 32 months, Mantel-Cox test P = 0.047). Conclusion: The majority of melanoma patients in our population were diagnosed in advanced stages with a higher risk for recurrence and progression into distant metastasis. Regional lymph node involvement and thicker tumor (T4) were associated with poor prognosis.