Japan Skin Cancer Society started to collect malignant melanoma patient data in Japan since 2005 (Japan Melanoma Study Group).  We have collected 4239 patients and to the best of our knowledge, the largest Japanese melanoma dataset ever reported. 
The male/female ratio was 1949/2287=0.85, female dominant. Average age at diagnosis was 64.0 years (median: 66). Most common site was foot (n=1412, 33.3%), followed by head/neck (n=602, 14.2%), trunk (n=615, 14.5%), hand (n=480, 11%), lower extremity except foot (n=378, 8.9%), mucosa (n=407, 9.6%), upper extremity except hand (n=196, 4.6%), primary unknown (n=91, 2.1%), ocular (n=44, 1.0%), and data missing (n=14, 0.3%). Clinical classification data was available in 3774 patients and the most common type was acral lentiginous melanoma (ALM, n=1700, 45.0%), followed by superficial spreading melanoma (SSM, n=870, 23.1%), nodular melanoma (NM, n=417, 11.0%), lentigo maligna melanoma (LMM, n=350, 9.3%), and mucosal melanoma (MUC, n=407, 10.8%). Ulceration was present in 1180 patients (39.2%). Pathological staging according to UICC/AJCC 2009 was available in 3555 patients and the number of each stages from Stage 0 to IV were n=736 (20.1%), n=806 (n=22.0%), n=788, (n=21.6%), n=776 (21.2%), and n=449 (n=12.3%), respectively. 
The 5-year disease specific survival rate (DSS) estimated by Kaplan-Meier method from Stage 0 to IV was 99.5%, 86.4%, 80.0%, 57.2%, and 18.8%, respectively. The number of patients with regional lymph node involvement and distant metastasis was higher than SEER database (regional: 21.2% vs 9% and distant: 12.4% vs 4%) and had lower 5-year DSS for regional disease (57.2% vs 62.9%).

Epidemiology of malignant melanoma in Japan: analysis of 4239 patient data.