Session Type: Abstract Submissions (ACR)
To examine the standardized incidence ratios (SIRs) and predictive factors for malignancy in a cohort of southern Chinese patients with inflammatory myopathies (IM).
Patients with polymyositis (PM), dermatomyositis (DM) or amyotrophic dermatomyositis (ADM) diagnosed between 2000 and 2010 in the three regional hospitals were studied. Diagnosis was made according to the Peter and Bohan criteria. Demographic data, clinical presentation, time of diagnosis of malignancies since diagnosis and the nature of malignancies were retrieved. Patients with malignancies diagnosed more than 1 year before the onset of IM was excluded. The age- and sex-adjusted standardized incidence ratios (SIRs) of malignancies in comparison to those of the general population obtained from the cancer registry of Hong Kong within the same study period were calculated. Demographic data, types of IM (DM vs ADM vs PM), creatine kinase (CK), presence of concomitant rheumatic diseases, extra-muscular manifestations were analyzed as predictors for malignancy in Cox regression models.
215 patients (65% women) with IM were studied (125 DM, 75 PM, 15 ADM) with a mean follow-up of 4.7±4.6 years. The mean age of disease onset was 51.5±16.3 years. Concomitant rheumatic diseases were diagnosed in 39 (18.1%) patients. 52 patients (24.2%) (44 DM, 6 PM, 1 ADM) were diagnosed to have malignancies. 13 (25%) and 14 (26.9%) malignancies, respectively, were identified within the preceding 1 year and at the same time of IM diagnosis. The mean time interval between the diagnoses of IM and malignancies was 1.29±1.56 years. The age- and sex-adjusted SIRs for malignancies for DM and PM were 3.9 [2.8-5.5] and 1.1 [0.5-2.6], respectively. The most frequently associated malignancies were: nasopharyngeal cancer 21 (40%), gastrointestinal cancer 10 (19%), lung cancer 10 (19%), breast cancer 4 (7.6%), cervical cancer 3 (5.7%), and the corresponding age- and sex-adjusted SIRs were 26.8 [16.5-41.5], 1.3[0.7-2.5], 1.8[0.9-3.5], 1.9[0.7-5.2], 8.4[2.6-26.5], respectively. On univariate analysis, the age at IM diagnosis (HR 1.03[1.02-1.05]), male gender (HR 3.88[1.95-7.74]), history of smoking (HR 3.86[1.95-7.65]), the diagnosis of DM (HR 3.37[1.39-8.14]), oropharyngeal muscle involvement (HR 2.55[1.28-5.07]) were associated with malignancies whereas the presence of concomitant rheumatic diseases (HR 0.23[0.05-0.95]), presence of interstitial lung disease (HR 0.37[0.16-0.85]) and use of azathioprine (HR 0.35[0.18-0.68]) were protective. Cox regression analysis revealed that a history of smoking (HR 2.7[1.12-6.56]), and oropharyngeal muscle involvement (HR 2.65[1.22-5.75]) were independently associated with malignancies.
DM, but not PM, was associated with an increased risk of malignancies compared to general population. DM patients in southern Chinese were particularly at risk of carcinoma of nasopharynx, lung and cervix.
C. C. Mok,
C. H. To,
K. Y. Ying,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/standardized-incidence-ratios-and-predictors-of-malignancies-in-215-southern-chinese-patients-with-inflammatory-myopathies/