Risk-stratified cancer screening in idiopathic inflammatory myopathies.

Abstract

e23127 Background: Idiopathic inflammatory myopathies (IIM) are high-risk cancer cohorts with 20–25% peri-onset malignancy, yet 83% diagnosed at stage III–IV. No consensus multidisciplinary screening pathway exists. We compared three screening strategies for early detection optimization. Methods: Systematic review and meta-analysis (PRISMA 2020) of 13 observational studies (n≈2,100; 69% good quality). Pooled proportion meta-analysis with random-effects modeling estimated peri-onset (≤3 years) cancer detection rates. Primary comparison: PET/CT vs. conventional screening (CI non-overlap); IMACS risk stratification (sensitivity, specificity, NPV). GRADE assessment applied. Results: PET/CT detected 24.6% (95% CI 19.1–30.9%) vs. conventional 11.5% (95% CI 9.2–14.3%); difference 13.1 pp (Z=2.18, p=0.029). IMACS risk stratification: 12.3% (95% CI 7.1–18.2%). Critically, standard-risk IMACS patients achieved 100% negative predictive value (0 of 12 cancers; p=0.028), enabling safe de-escalation. High-risk patients: 17.9% cancer incidence. Real-world survey (Dutton et al.): 77% of clinicians lack consensus; no standardized oncology-rheumatology pathway. Conclusions: Risk-stratified IMACS screening with selective PET/CT outperforms conventional screening. IMACS 100% NPV in standard-risk patients supports safe de-escalation, while high-risk patients (17.9% incidence) warrant PET/CT. Multidisciplinary implementation framework needed: (1) IMACS risk stratification at diagnosis; (2) PET/CT for high-risk; (3) age-appropriate screening for standard-risk; (4) rheumatology-oncology shared decision-making. Comparison of screening strategies. Modality Detection Rate (95% CI) Sensitivity Specificity Key Finding Evidence Conventional Screening 11.5% (9.2–14.3%) 45–62% 70–82% 37% miss rate; unreliable LOW PET/CT 24.6% (19.1–30.9%) 67–94% 80–98% 2.1× higher yield; more false positives LOW IMACS Risk-Based 12.3% (7.1–18.2%)* 82–91% 72–78% High-risk 17.9% vs. standard-risk 0% (100% NPV) LOW Whole-Body MRI 13.0% 71% 85% Radiation-free; limited evidence (n=1) VERY LOW