U.S. Study Validates IMACS Guidelines for Detecting High Cancer Risk in Dermatomyositis Patients

• Patients with dermatomyositis have an increased malignancy risk, warranting additional screening.
• Using international guidelines, this study found that 8.8% of patients considered high risk had paraneoplastic dermatomyositis, indicating a cancer diagnosed within three years before or after disease onset.
• The single‑center analysis helps validate the discriminatory ability of the risk‑stratification guidelines for identifying increased cancer risk, according to the researchers.

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 high‑risk group had paraneoplastic dermatomyositis, compared with 5.1% of the intermediate‑risk group and 2.5% of the low‑risk group.

Overall, 6.5% of the study population had paraneoplastic dermatomyositis, meaning a cancer was identified in the three years before or after dermatomyositis onset, 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 also receive continued monitoring, 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,” wrote Khattri and colleagues. “This may be due to the small sample size and limited number 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 within three 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.

The IMACS guidelines define risk groups based on various clinical factors and disease markers. High‑risk patients are classified based on IIM subtype, presence of anti‑TIF1γ or anti‑NXP2 antibodies, age ≥ 40 at diagnosis, persistent high disease activity despite therapy, dysphagia, and cutaneous necrosis. According to the guidelines, high‑risk patients should undergo more extensive screening following DM diagnosis, including basic and enhanced screening panels and follow‑up screenings at 1‑, 2‑, and 3‑year visits.

Khattri and colleagues performed an external validation of the IMACS risk categories using data from a metropolitan U.S. academic center. Their study retrospectively reviewed records of 413 patients (age range: 18–92 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 dermatomyositis (average 12.6 months earlier), with the remainder diagnosed afterward (average 23.1 months later). The most common cancers were 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 classified as high risk (70%) by IMACS guidelines, 22% as intermediate risk, and 8% as low risk.

About half of the patients were white and more than three‑fourths were women (89% in the paraneoplastic group). 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.

Limitations included the retrospective, single‑center design, the small number of paraneoplastic dermatomyositis cases, limited follow‑up for some patients, and the requirement that patients had at least two visits, which could have excluded some cases.

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