ABSTRACT It has been recognized for some time now, that compared with the normal population, patients with idiopathic inflammatory myopathies (IIM) live with an increased risk of developing malignancy. In the majority of these patients, cancer-associated myositis appears to have some paraneoplastic features. The aim of the present review is to describe new data that explain the connection between myositis and malignant diseases, as well as to highlight its value in the current management of these patients.
Antigen expressions and patterns shared by regenerating muscle and cancers raise questions about whether myositis cases without clinically observable cancer may represent a fully successful antitumor immune response with bystander damage to regenerating muscle. The discovery of anti-155/140 autoantibody may aid in the better diagnosis of adult IIM patients with a higher risk of malignancy. It also may help the better understanding of paraneoplastic myositis.
Cancer-associated myositis differs from primary myositis in many aspects. Prognosis and life-expectancy are determined by the underlying malignancy. Therefore, patient-specific examinations for detection of an underlying cancer are important in the management of patients. Recent clinical findings and new possibilities in immunoserological testing may result in the elaboration of an evidence-based recommendation for cancer screening programs in patients with IIM in the future.
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ABSTRACT: The association of idiopathic inflammatory myositis (IIM) and malignancies has been reported, but rarely in Asian countries. Our aim was to investigate the risk of cancer among IIM patients without a prior history of malignancies, in Taiwan. We conducted a nationwide cohort study of 1,012 patients with dermatomyositis (DM) and 643 patients with polymyositis (PM), but without prior history of malignancies, utilizing the National Health Insurance Database from 1997 to 2007. Standardized incidence ratios (SIRs) of cancers were analyzed. A total of 95 cancers (9.4%) in DM and 33 cancers (4.4%) in PM were identified. Overall cancer risk was significantly elevated in DM patients (SIR = 5.11, 95% confidence interval [CI] = 5.01 to 5.22) and PM patients (SIR = 2.15, 95% CI = 2.08 to 2.22). Most cancers were detected in the first year of observation. The risk of cancer decreased with observation time, yet remained elevated compared with the general population in both study groups after 5 years of follow-up. DM was associated with sustained elevated risk of cancers in every age group, whereas the risk of cancer in PM was highest in younger patients and decreased with age. DM patients were at the greatest risk of cancers of the nasopharynx, lungs and hematopoietic malignancies. Patients with IIM are at increased risk for cancer and should receive age-appropriate and gender-appropriate malignancy evaluations, with additional assessment for nasopharyngeal, lung and hematologic malignancy following diagnosis, and with continued vigilance for development of cancers in follow-up.Arthritis research & therapy 01/2010; 12(2):R70. · 4.27 Impact Factor