Multivariable prognostic analyses of Chinese acral and cutaneous melanoma after surgical treatment for the past five years in a single cancer center

Background and purpose: The prognosis of malignant melanoma (MM) in China and Asia is significantly worse than that of European and American populations, mainly because acral melanoma (AM) is inferior to cutaneous melanoma (CM) in terms of biological behavior, clinical features, prognosis, and efficacy of drugs (mainly immunotherapy). Certain changes have occurred in the last 5 years in the choice of surgical and drug-adjuvant treatment for MM. This study retrospectively analyzed the survival outcomes of Chinese CM and AM patients after surgical treatment in a single cancer center for the past five years. Methods:Data of melanoma patients undergoing surgical treatment were retrospectively collected from 2017 to 2021 in Fudan University Shanghai Cancer Center. The basic clinical characteristics, pathological features, lymph node tumor burden and survival information were carefully collected from medical document. Patients with mucosal subtype, unknown primary sites, or follow-up less than 6 months were excluded. Survival analysis and multivariable Cox regression analysis were performed to explore prognosis and associated risk factors. Results:Totally 585 patients were enrolled, including 397 AM and 188 CM patients. The median age was 59 (19-89) years, and 54% were female. AM and CM patients differed in gender, age, primary tumor location, gene mutation distribution and adjuvant therapy, but not in tumor burden associated factors including the Breslow thickness, ulceration and lymph node involvment. The median follow-up time was 24 months, and the median relapse-free survival (mRFS) was 36 months, with 1-year and 2-year RFS of 75.6% and 61.2%, respectively. However, there was no statistically significant difference in prognosis between the two subtypes. Primary ulceration (HR=2.265, 95% CI: 1.257-4.080), NRAS mutation (HR=1.816, 95% CI: 1.211-2.725) and advanced N stage (HR of N1, N2 and N3 versus N0 were 1.850, 4.085 and 4.191, respectively) were independent prognostic risk factors for RFS in AM; while the protective factors were female (HR=0.636, 95% CI: 0.433-0.933) and upper extremity primary lesions (HR=0.259, 95% CI: 0.105-0.639). Independent risk factors for RFS in CM included primary ulceration (HR=4.073, 95% CI: 1.718-9.654), and later N stage (HR=5.482, 95% CI: 2.385-12.601 for N3 stage). Conclusion: High tumor burden of primay lesion still deteriorates overall outcomes for both AM and CM, while harboring NRAS mutation might suggest even worse outcome for AM.