Abstract
Abstract Spindle cell melanoma (SCM) is a rare morphological subtype of melanoma, characterized histologically by atypical, spindled, malignant melanocytes (Weissinger SE, Keil P, Silvers DN et al. A diagnostic algorithm to distinguish desmoplastic from spindle cell melanoma. Mod Pathol 2014; 27:524–34). SCM often manifests as a broad metastatic illness, is frequently amelanotic and can arise nearly anywhere on the body, making diagnosis challenging (Xu Z, Shi P, Yibulayin F et al. Spindle cell melanoma: incidence and survival, 1973–2017. Oncol Lett 2018; 16:5091–9). Given the rarity of SCM, the epidemiology is not yet well explored. The National Cancer Database (NCDB) is a nationwide oncology outcome database for > 1500 commission-accredited cancer programmes in the US and Puerto Rico. This study aimed to investigate the demographic factors associated with patients diagnosed with SCM by analysis of the NCDB. A retrospective cohort analysis utilizing data from the NCDB from 2004 to 2020 included patients diagnosed with histologically confirmed SCM (n = 7556). Sociodemographic factors (sex, age, race, Hispanic status, insurance type, urban/rural designation, facility location, facility type, education, income, distance from residence to facility and Charlson–Deyo score) were analysed using Pearson χ2-tests, and multivariate analysis was performed via binary logistic regression. Since 2004, an average (SD) of 480.8 (63.7) cases have been diagnosed annually. Most patients were male (66.5%), White (97.6%), not Hispanic (95.2%) and insured by Medicare (56.3%) and lived in an urban area (98.5%). Mean (SD) age at diagnosis was 67.9 (14.5) years, with an average (SD) Charlson–Deyo comorbidity score of 0.3 (0.6) and a mean (SD) distance of 37.3 (113.4) miles from the patient’s residence to the hospital. The most common primary site for SCM was the skin of the upper limb and shoulder (22.6%), followed by skin of the scalp and neck (19.0%), skin of other and unspecified parts of face (17.9%), and skin of the trunk (17.3%). On multivariate analysis, males were more likely than females to be diagnosed at an older age [69.3 vs. 65.3 years, 95% confidence interval (CI) 0.979–0.990; P < 0.001], receive treatment at an academic facility (45.9% vs. 42.7%, 95% CI 1.018–1.270; P = 0.023) and have a Charlson–Deyo score of ≥ 3 (2.1% vs. 1.3%, 95% CI 0.374–0.924; P = 0.21). Given the lack of literature on SCM, this study serves as a valuable tool for understanding the demographic factors associated with the diagnosis. Future studies within the laboratory aim to determine the effect of these factors on overall survival with propensity score matching for other variables to identify disparities.