Study of 364 Japanese myositis (IIM) pts - 42 (11.4%) had cancer-assoc myositis (CAM); 30/42 Dx w/in ±1 yr of IIM. CA risk incr ±3 yrs of IIM (SIR 2.54), highest 1st yr (SIR 8.66). 5 factors predicted CAM: TIF1γ +, ^CRP, dermatomyositis, older age, +FHx CA (AUC 0.86; sensitivity https://t.co/9ojTWTK5kO