Allenbach Y, Keraen J, Bouvier A, et al. High Risk of Cancer in Autoimmune Necrotizing Myopathies: Usefulness of Myositis Specific Antibody. Brain 2016;139:2131-2135.
Submitted by Andrew W. Tarulli, MD, News Science Editorial Board
Allenbach and colleagues investigated the incidence of cancer in patients with necrotizing autoimmune myopathies. A cohort of 115 patients was divided into those with anti-signal recognition particle (SRP) antibodies (49 patients), anti-HMGCoA reductase (HMGCR) antibodies (52 patients), and seronegative (SN) necrotizing autoimmune myopathies (14 patients). These patients were considered to have a synchronous cancer if the cancer was diagnosed up to 3 years before or the after the diagnosis of myopathy. Malignancies were identified in 28.6% of SN patients, 17.3% of HMGCR patients, and 8.1% of SRP patients. The cancer risk compared to an age- and sex-matched population was 8.35 for the SN patients, 2.79 for the HMGCR patients, and 1.65 for the SRP patients. No specific cancer was identified as being particularly common in any of the groups or in the population with necrotizing autoimmune myopathy as a whole.
The association of cancer with inflammatory myopathies, particularly dermatomyositis, is well known. It is hypothesized that an anti-tumor immune response is etiologically related to the myositis. This study sheds light on the relationship between necrotizing autoimmune myopathy antibody status and malignancy. Clear increases in cancer risk with HMGCR antibodies and seronegative patients were identified. Although the authors found that the rate of cancer in SRP antibody patients was not statistically greater than a matched population, some caution needs to be exercised before abandoning cancer screening in this group. Unfortunately, the study did not identify any specific cancer as being frequently associated with necrotizing autoimmune myopathies, a finding that precludes a targeted screening strategy.
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