P-10 Malignancies associated with idiopathic inflammatory myopathies: a 35-years retrospective study

An increased incidence of malignancy in patients with poly/dermatomyositis (PM/DM) has been reported; several points remain unclear: incidence and the predictive factors for the presence of cancer and its prognosis. Aim of the study was to evaluate the frequency of malignancy among myositis patients diagnosed in our Unit in a 35 years follow-up (from 1975 to 2010). We compared epidemiological, clinical, serological and survival data of the patients with cancer associated myositis (CAM) with the findings of primary myositis, trying to define predictive factors for malignancies development. 162 primary PM/DM patients were enrolled by our Rheumatology Unit. Diagnosis of PM/DM was based on Bohan and Peter criteria (1975). Myositis was considered tumor-associated if diagnosed within 2 years before or after the diagnosis of cancer. Concerning the comparison of CAM and primary myositis, we analyzed: age, sex, systemic symptoms (Raynaud’s phenomenon, dysphagia, dyspnea, fever, arthritis, dysphonia), creatinekinase (CK) levels at onset, autoantobodies, number of deaths, survival rates. Out of 162 patients with myositis, cancer was present in 18/72 DM patients (25%) and in 9/90 PM patients (10%). In 10 cases the malignancy and myositis appeared simultaneously; in 6 cases the tumor was diagnosed before and in 11 after the onset of myositis; cancer types more frequent were breast and ovarian carcinoma. Patients with CAM were older than those without cancer (59 yr vs. 51yr) p < 0.01. There was a female predominance in primary myositis group (M/F = 30/51 in PM and 13/41 in DM) and in CAM-DM (6/12) while CAM-PM patients were equally shared.Dysphagia was more frequent in CAM than in primary myositis patients (37% vs. 17,5%) p < 0.035; in the CAM subgroup was more present in DM than PM (44% vs. 14%) p < 0.006. Prevalence of other extramuscolar features was similar in the 2 subgroups. In patients with CAM, CK medium levels were lower in than in primary myositis (3013 U/L vs. 2412 U/L); positive ENA were significantly more present in primary myositis group (20% vs. 7%). AntiJO1 antibodies were detectable in 6% of PM/ DM patients but not in cancer group. 22/135 (16%) with primary myositis and 15/27 patients with CAM (55%) died; in this second group deaths were in the first two years from diagnosis and in 13/15 patients were caused by cancer. The survival rate of primary PM/DM at 5 years was significantly higher (87% and 74%) compared to the CAM patients, where survival at 2 years was 56% for PM and 44% for DM. The risk of cancer is significantly higher in older female patients with DM. Some clinical and serological features can be considered predictive risk factors for malignancy, although without statistical significance: dysphagia, lower CK levels, lower prevalence of anti-ENA antibodies. The overall survival rates were considerably worse in CAM; early discovery of malignancy is crucial and examinations for detections of an underlying malignancy are important in the management of patients with PM/DM.