Malignancy-Associated Dermatomyositis Predicted by Disease Subtype, Older Age

Older age and classic dermatomyositis (DM) were identified as independent risk factors for malignancy-associated DM in study data published in the Journal of the American Academy of Dermatology. Patients with these risk factors were more likely to have an underlying malignancy than younger patients and patients with clinically amyopathic DM (CADM).

Investigators conducted a retrospective cohort study of adult patients who were enrolled in the University of Pennsylvania’s longitudinal DM database from July 2008 to April 2018. Demographics and laboratory data, medical history, and malignancy diagnoses were ascertained from the database or from medical record review. Patients were categorized as having either classic DM (CDM) or clinically amyopathic DM (CADM) based on established dermatologic criteria. The primary outcome was diagnosis of malignancy within ±2 or ±5 years of DM onset, excluding nonmelanoma skin cancer. Patients who developed malignancies within these time periods were classified as having malignancy-associated DM; all other patients were classified as having non-malignancy-associated DM. Multivariable logistic regression analysis was performed to identify risk factors for malignancy-associated DM, including age at DM diagnosis, sex, race/ethnicity, and DM subtype. Results were presented as odds ratios (ORs).

Data were extracted from the records of 201 patients with adult-onset DM; 142 (71%) had CDM and 59 (29%) had CADM. Demographic characteristics were similar between CDM and CADM subgroups, although the CDM subgroup had a greater percentage of men (16.9% vs 3.4%; P =.01). Overall, a greater percentage of patients with CDM vs CADM developed malignancies within ±2 years (9.9% vs 1.7%; P =.07). In multivariable regression analyses, CDM subtype (odds ratio [OR], 8.6; 95% CI, 1.05-70.08; P =.04) and older age (OR, 1.07; 95% CI, 1.01-1.12; P =.01) were significant independent risk factors for malignancy-associated DM within 2 years of DM onset. A greater percentage of patients with CDM developed malignancies within 5 years compared with the CADM subtype (13.9% vs 5.4%, respectively; P =.24), although the difference was not significant. In multivariable regression analysis, older age was the only significant predictor of malignancy within 5 years (P =.01).

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From these data, investigators hypothesized that patients with CDM may benefit from more frequent malignancy screenings during the first 5 years following DM onset. In addition, older patients may be at increased malignancy risk.

As a study limitation, investigators cited the retrospective analysis of prospectively collected data; figures may not have been up to date, and some data points were missing. However, the results suggest that “clinicians should consider more aggressive or frequent malignancy screening in older patients with CDM in the first 2 years after DM onset,” the investigators wrote.

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Bowerman K, Pearson DR, Okawa J, Werth VP. Malignancy in dermatomyositis: a retrospective study of 201 patients seen at the University of Pennsylvania [published online March 2, 2020]. J Am Acad Dermatol. doi:10.1016/j.jaad.2020.02.061