Real-world application of the international myositis assessment and clinical studies group guidelines on cancer risk stratification

OBJECTIVES: The 2023 International Myositis Assessment and Clinical Studies Group (IMACS) guidelines introduced a standardized risk-stratification model for cancer screening in idiopathic inflammatory myopathies (IIM). However, real-world data on their application remain limited. This study aimed to evaluate the effectiveness of IMACS-based risk stratification in predicting malignancy and assess adherence to cancer screening recommendations in a multicentric Italian IIM cohort. METHODS: We conducted a multicentre retrospective study including 411 IIM patients from five Italian rheumatology centres, classified into IMACS-defined standard, intermediate and high-risk groups. Cancer occurrence within three years of IIM diagnosis was assessed. Screening practices prior to the implementation of IMACS guidelines were compared with their recommendations. Logistic regression analysis was used to evaluate the predictive value of IMACS stratification. RESULTS: Among 411 patients, 180 (43.8%) were classified as high-risk, 156 (37.7%) as intermediate-risk and 75 (18.2%) as standard-risk. Cancer was diagnosed in 9.2% of patients within three years of IIM onset, with high-risk patients significantly more likely to develop malignancy (OR = 4.05, P = 0.026). Anti-TIF1γ (OR = 12.3, P < 0.001) and anti-SAE1 (OR = 11.9, P = 0.012) were independent predictors of cancer. Screening adherence varied, with underutilization of enhanced screening in intermediate-risk patients and a decline in screening over time. CONCLUSION: The IMACS stratification model effectively predicts cancer risk in IIM. However, real-world screening practices show inconsistencies, particularly in intermediate-risk patients. These findings support the need for optimized, risk-adapted malignancy surveillance in IIM and refinement of current guidelines based on real-world data.