Prognostic factors for patients with cancer-associated dermatomyositis: a retrospective, multicentre cohort study of 73 patients

Objectives: To investigate factors associated with DM complete clinical response and overall survival with a focus on the use of immunosuppressive therapies in patients with cancer-associated DM. Methods: We performed a multicentre, retrospective cohort study. Multivariable survival analyses used a Cox model with time-dependent covariates and adjustments with inverse probability censoring weighting. Results: We included 73 patients with cancer-associated DM. Median follow-up was 3.92 years. Overall, 40 (54.8%) patients achieved cancer remission, with DM complete clinical response in 28/40 (70.0%). DM complete clinical response was associated with cancer remission (hazard ratio [HR] 2.46, 95% CI [1.13-5.32]) and younger age (HR 0.68, 95% CI [0.49-0.95]). Risk of mortality was associated with sustained cancer activity (HR 12.93, 95% CI [2.42-69.25]), male sex (HR 2.82, 95% CI [1.19-6.70]), and older age (HR 1.86, 95% CI [1.26-2.79]) but not sustained DM activity (HR 0.40, 95% CI [0.13-1.26]). Oral corticosteroid use was a protective factor only on univariate analysis (HR 0.18, 95% CI [0.08-0.42]). Conclusion: This study provides strong evidence of a significant association between the evolutions of DM and cancer, both in terms of overall survival and DM complete clinical response. Immunosuppressive treatments for DM were not significantly associated with mortality. Trial registration: ClinicalTrials.gov, NCT04637672.