Clinical Characteristics and Mortality Outcomes in Cancer-Associated Dermatomyositis: A Systematic Review and Meta-Analysis

Background: Approximately 15% to 25% of adult dermatomyositis cases are associated with underlying cancers. To date, no study has comprehensively synthesized the available evidence on mortality in cancer-associated dermatomyositis. Objective: To explore the clinical characteristics, mortality, and survival outcomes of cancer-related dermatomyositis. Methods: MEDLINE, Embase, and PubMed were searched from inception to August 5, 2025 (PROSPERO CRD420251269785). Observational studies including at least 10 cases and reporting mortality outcomes among adults with cancer-associated dermatomyositis were eligible. Risk of bias and certainty of evidence were assessed using the Grading of Recommendations Assessment, Development, and Evaluation. Random-effects meta-analysis was used to estimate pooled survival outcomes. Results: Twenty-three studies including 974 patients were analyzed with a mean age of 58 years and a female predominance. Head and neck cancers were the most frequently reported malignancies, reflecting population patterns. Muscle weakness, heliotrope rash, and dysphagia were common. Across 16 studies including 605 patients, cancer was diagnosed in the majority of cases (82%) within 2 years of dermatomyositis onset. Patients with cancer-associated dermatomyositis had higher mortality rates than those without malignancy, with worse 1- and 5-year survival (low certainty of evidence). Only 2 studies assessed mean survival time, with a pooled estimate of 4.57 years from dermatomyositis diagnosis (95% CI, 2.08-7.05; I 2 = 0%). Conclusions: This review synthesizes the available evidence on cancer-associated dermatomyositis and reinforces its association with poor prognosis. Larger studies with standardized reporting of serological profiles and mortality outcomes are needed to better characterize survival and prognostic factors.