Guidelines Help Spot Dermatomyositis Patients at High Risk for Cancer

International guidelines can help identify dermatomyositis patients with a particularly high risk for cancer, according to a retrospective single-center U.S. study.

Among 413 patients with a known dermatomyositis diagnosis, risk stratification using International Myositis Assessment and Clinical Studies Group (IMACS) guidelines showed that 8.8% of the group considered high risk had a paraneoplastic dermatomyositis, as did 5.1% of the intermediate-risk group and 2.5% of the low-risk group.

Overall, 6.5% of the study population had a paraneoplastic dermatomyositis, meaning a cancer in the 3 years before or after the onset of dermatomyositis, reported Saakshi Khattri, MD, of the Icahn School of Medicine at Mount Sinai in New York City, and colleagues in ACR Open Rheumatology.

The findings support the discriminatory ability of the IMACS risk stratification guidelines and suggest that intermediate-risk patients should receive continued monitoring as well, the researchers said.

“Although two or more high-risk factors were not significantly associated with malignancy, age ≥40 years was significantly associated with paraneoplastic DM [dermatomyositis],” wrote Khattri and colleagues. “This may be due to the small sample size and small amount of paraneoplastic DM cases. However, it shows that the IMACS guidelines are clinically useful for identifying high-risk populations.”

Dermatomyositis carries an increased risk for malignancy, especially in the 3 years before or after disease onset, with lymphomas and cancers of the lung, ovary, colon, breast, and nasopharynx most commonly associated with the autoimmune disease.

A subtype of idiopathic inflammatory myopathy (IIM), dermatomyositis can cause progressive systemic damage to the muscles, skin, joints, and gastrointestinal tract, as well as major organs such as the lungs and heart.

Guidelines from IMACS defines risk groups based on various clinical factors and disease markers.

“High-risk patients are classified based on IIM subtype, anti-TIF1γ or anti-NXP2 antibodies, age ≥40 at diagnosis, persistent high disease activity despite therapy, dysphagia, and cutaneous necrosis,” the researchers explained. “Based on the guidelines, high-risk patients should undergo more extensive screening following [a] DM diagnosis, including basic and enhanced screening panels and follow-up screenings at 1-, 2-, and 3-year follow-up visits.”

Khattri and colleagues aimed to perform an external validation of the IMACS risk categories using data from a metropolitan U.S. academic center. Their study retrospectively reviewed the records of 413 patients (age range: 18 to 92 years) diagnosed with dermatomyositis or clinically amyopathic dermatomyositis from 2019 to 2024 at the Mount Sinai Health System.

Overall, 52 of the patients (12.6%) had a cancer diagnosis in their lifetime.

In the 27 patients with paraneoplastic dermatomyositis, a third had their cancer diagnosed before the onset of their dermatomyositis (12.6 months earlier on average), with the rest of the malignancies diagnosed afterward (23.1 months later on average). The most common cancers were those of the breast (37%) and lung (19%), with others including uterine cancer (7%), non-Hodgkin lymphoma (7%), cervical cancer (4%), and other cancers (26%).

Most of the patients with paraneoplastic dermatomyositis were considered high risk (70%) according to IMACS, with 22% considered intermediate risk and 8% low risk.

About half of the patients were white and more than three-fourths were women (89% in the paraneoplastic group). The paraneoplastic patients tended to have their dermatomyositis onset at an older age (60 vs 48 years).

“Notably, most cancers were identified using modalities consistent with IMACS-recommended screening, such as colonoscopy, mammography, pelvic ultrasonography, and CT imaging,” according to Khattri and colleagues.

Myositis-specific autoantibody positivity and myositis-associated autoantibody positivity were not significantly associated with increased risk of paraneoplastic dermatomyositis in the study.

Beyond the retrospective and single-center design, other study limitations included the small number of paraneoplastic dermatomyositis cases and limited follow-up for some patients. The analysis also required that patients had at least two visits, which could have excluded some cases.

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