High risk of cancer in autoimmune necrotizing myopathies: usefulness of myositis specific antibody

Abstract

Cancer can occur in patients with inflammatory myopathies. This association is mainly observed in dermatomyositis, and myositis-specific antibodies have allowed us to delineate patients at an increased risk. Malignancy is also reported in patients with necrotizing autoimmune myopathies, but the risk remains elusive. Anti-signal recognition particle or anti-HMGCR antibodies have been specifically associated with necrotizing autoimmune myopathies. We aimed at screening the incidence of cancer in necrotizing autoimmune myopathies. A group of patients (n = 115) with necrotizing autoimmune myopathies with or without myositis-specific antibodies was analysed. Malignancy occurred more frequently in seronegative necrotizing autoimmune myopathies patients and in HMGCR-positive patients compared to anti-signal recognition particle positive patients. Synchronous malignancy was diagnosed in 21.4% and 11.5% of cases, respectively, and incidence of cancer was higher compared to the general population in both groups. No specific type of cancer was predominant. Patients suffering from a synchronous cancer had a decreased median survival time. Cancer screening is necessary in seronegative necrotizing autoimmune myopathies and in HMGCR-positive patients but not in anti-signal recognition particle-positive patients.

Immune-Mediated Necrotizing Myopathy

“…Specifically, autoantibody-negative IMNM has been associated with a markedly increased risk of malignancy (95%SCR CI: 8.35–24.41) [30••]. In contrast, anti-HMGCR myopathy may have a relatively weak association with cancer (95%SCR CI: from 0.4–2.4 to 1.02–6.07) [30••], although this has not been demonstrated in all cohorts [21••, 31•, 32•, 33••]. Finally, anti-SRP myopathy is not associated with cancer [13••, 16••, 30••, 33••, 34•].…”

Autoimmune necrotising myopathy and HMGCR antibodies

“…A recent study of 115 patients identified malignancy in 17.3% in the anti-HMGCR cohort, with lung, breast, renal, oesophagus, gastric, ovarian and endometrial cancers detected 6. We typically perform whole-body fluorodeoxyglucose positron emission tomography-CT imaging, with or without gastrointestinal endoscopy, with testicular ultrasound in men and mammograms in women.…”

Statin-related myopathies

“…Increasingly, they have been found in association with immune-mediated necrotising myopathies in patients who have never been exposed to statins, including children. Furthermore, there is mounting evidence of an increased incidence of cancer in people with HMGCR related immune-mediated necrotising myopathy, with or without a history of statin exposure 32. This needs further study, but on current evidence, it seems reasonable practice to consider the possibility of underlying malignancy in adults presenting with immune-mediated necrotising myopathy with HMGCR antibodies, as one should do with patients presenting with dermatomyositis.…”