A Scoring System Based on [ 18 F]PFPN PET and Clinical Features for Predicting Prognosis in Patients With Mucosal Melanoma.

Purpose: This study aims to establish a prognostic prediction system for mucosal melanoma patients by integrating melanocyte-targeting PET with clinical parameters.

Patients and methods: A retrospective study was conducted on primary mucosal melanoma patients who underwent [ 18 F]PFPN PET scans between January 2021 and April 2024. Researchers manually delineated all lesions on the [ 18 F]PFPN PET images and recorded the imaging features. Kaplan-Meier survival analysis, Cox regression, and stepwise regression were used to analyze prognosis and construct the prediction model.

Results: Fifty patients (mean age 60.5±8.8 y) were included, with a median follow-up of 13 months (1-39 mo) and an average survival of 14.62 months. Multivariate analysis showed that lower Whole-body Melanotic Tumor Volume (WBMTV), earlier stage, younger age, immunotherapy, and head and neck or vulvar subtypes were associated with longer overall survival (OS, P <0.05). A simplified prognostic scoring system was developed based on 5 variables: stage (not detected or I/II/III/IV: 0/5/10/15 points), age (<60/≥60: 0/10), WBMTV (<1.52/≥1.52: 0/10), immunotherapy (yes/no: 0/5), and subtype (head and neck or vulva/others: 0/10). Patients were stratified into low (0-19), intermediate (20-29), and high-risk (30-50) groups. The model's concordance index was 0.85, outperforming the clinical staging (0.76). OS declined progressively from low-risk to high-risk groups, with 1-year survival from 100% to 74.6% and 3-year survival from 100% to 0%.

Conclusions: [ 18 F]PFPN PET provides an accurate assessment of mucosal melanoma burden, and a prognostic model combining [ 18 F]PFPN PET features and clinical data offers reliable stratification of patient outcomes.