Myositis and cancer

Albert Selva-O’Callaghan MD PhD (

Dr. Selva-O'Callaghan of Universitat Autonoma Barcelona received speaker fees from Werfen and Innova Diagnostics.

Ernesto Trallero-Araguas MD PhD (

Dr. Trallero-Araguas of the Vall d’Hebron General Hospital received honorariums from Bristol-Myers Squibb, Roche, and MSB as a guest speaker.

Francesc Graus MD PhD, editor. (

Dr. Graus, Emeritus Professor, Laboratory Clinical and Experimental Neuroimmunology, Institut D’Investigacions Biomédiques August Pi I Sunyer, Hospital Clinic, Spain, has no relevant financial relationships to disclose.

Originally released September 9, 2019; last updated August 31, 2020; expires August 31, 2023


There is a well-recognized association between cancer and myositis, mainly seen in classic dermatomyositis, amyopathic dermatomyositis, and immune-mediated necrotizing myopathy.

Idiopathic inflammatory myopathies, referred to as “myositis”, can be associated with cancer. Classic dermatomyositis, amyopathic dermatomyositis, and, to lesser extent, polymyositis are the most highly affected myositis phenotypes, whereas immune-mediated necrotizing myopathy has been linked to cancer as a paraneoplastic phenomenon. Cancer-associated myositis is defined as the concomitant presence of the 2 diseases within a 3-year period. However, a paraneoplastic pattern—that is, when cancer abates, myositis disappears and when malignancy recurs, myositis returns—is not always observed.

Key points


• The myositis phenotype most often associated with cancer is dermatomyositis.


• The temporal criterion (cancer and myositis diagnosed within 3 years) is mandatory for the diagnosis of cancer-associated myositis.


• EUCLIDES (epidemiological useful clinical-laboratory-imaging development screening) is a proposed strategy for cancer screening in patients with myositis.


• The outcome of cancer-associated myositis depends more on the cancer than on the myositis.


• Close collaboration between the myositis-treating physician and oncologist is essential for optimal management of patients with cancer-associated myositis.

Historical note and terminology

Idiopathic inflammatory myopathies, generally referred to as myositis, are a heterogenous group of diseases, systemic in nature and likely of autoimmune origin, characterized by an inflammatory infiltrate in muscle specimens (Dalakas 2015). Five myositis phenotypes are currently recognized (Selva-O'Callaghan et al 2018a): dermatomyositis, which, when muscle symptoms are absent, is called amyopathic dermatomyositis; polymyositis, currently considered a rare condition and an exclusion diagnosis; necrotizing myopathy, which is mainly immune-mediated; sporadic inclusion body myositis; and overlap myositis, which includes the rare antisynthetase syndrome, manifesting as myositis, interstitial lung disease, and arthritis, among other features.

Myositis was first described in the late 19th century (Virchow 1866; Levine 2003) and its association with malignancy was reported some years later (Kankeleit 1916; Stertz 1916; Levine 2003). In the first classification of inflammatory myopathies (Bohan and Peter 1975), the authors established the criteria for polymyositis and dermatomyositis and recognized that an association between cancer and myositis was clearly found in some patients, mainly those with dermatomyositis. Well-conducted epidemiological studies found that dermatomyositis is the myositis phenotype most often associated with cancer, with polymyositis involved to a lesser extent (Sigurgeirsson et al 1992; Buchbinder et al 2001; Hill 2001). Unfortunately, studies focused on other myositis phenotypes are scarce and often of poor quality. A few observational or cohort studies have reported a higher risk of cancer relative to the general population in patients with immune-mediated necrotizing myopathy, particularly those without autoantibodies, and a weaker association in those with antibodies against 3-hydroxy-3-methylglutaryl coenzyme A (anti-HMGCR) (Allenbach et al 2016).

Current recommendations advocate taking into consideration the span of time between the 2 conditions to establish an association. A period of 3 years is now generally accepted; that is, cancer occurring within 3 years of the myositis diagnosis (Troyanov et al 2005).

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