AB0243 ANALYSIS OF CANCER SCREENING PERFORMANCE IN PATIENTS DIAGNOSED WITH IDIOPATHIC INFLAMMATORY MYOPATHY
Authors: L. Leeves, V. Thanopoulou, T. Malley, A. Singh, R. Stratton
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> The idiopathic inflammatory myopathies (IIM), generally referred to as myositis, are a group of connective tissue diseases characterised by progressive muscle weakness and inflammatory infiltrates in muscle tissue. There is a strong association between adult-onset IIM and malignancy. Guidance for IIM-associated cancer screening, recently published by the International Myositis Assessment and Clinical Studies Group[1], stratifies individuals diagnosed with IIM into high-, moderate-, and standard-risk of IIM-related cancer. All patients, irrespective of risk group, require basic screening at diagnosis. Those in the moderate- and high-risk groups should have basic and enhanced screening. The high-risk group requires additional basic screening at 1, 2 and 3 years after IIM diagnosis, and consideration of a PET-CT scan and/or endoscopy at initial presentation; particularly in patients over the age of 40 with a positive anti-TIF1γ antibody. <h3>Objectives:</h3> To determine the performance rate of cancer screening investigations in patients diagnosed with IIM in accordance with the recent screening guidance. <h3>Methods:</h3> Clinical records were reviewed for adult patients diagnosed with IIM (n=46), between 2018 and 2023, who were treated with intravenous immunoglobulin or rituximab at a tertiary rheumatology centre. Cancer screening performance was checked against the current guidance, accounting for risk stratification. <h3>Results:</h3> Of the 46 patients, 18, 20 and 8 fell into the high-, moderate- and standard-risk of IIM-related cancer groups, respectively. Out of 46 patients, 15 received appropriate screening. Of the remaining 31 patients, screening was incomplete. The most frequently missing investigation was protein electrophoresis, not performed in 59% of cases. Further breakdown of basic screening investigations is demonstrated in Figure 1. Out of 38 patients in the moderate- and high-risk groups, screening was incomplete in 37; the most frequently missing tests being faecal occult blood (92% not performed), CT neck (89% not performed) and pelvic/transvaginal US and CA-125 (60% not performed). Of the recommended tests for moderate- and high-risk patients, CT scan of chest, abdomen and pelvis was the most consistently performed, in 42% of the cases. PET-CT scans were performed in 16 of 46 patients; 11 of whom were in the high-risk group, and 5 of whom were in the moderate-risk group. At the time of data collection, of the 12 patients in the high-risk group who had been diagnosed over one year prior, only 1 (8%) had undergone <i>year 1</i> annual re-screening. Similarly, this was observed to be case in 1 out of 7 (14%) and 1 out of 5 (20%) patients at <i>year 2</i> and <i>year 3</i> re-screening, respectively. Mortality rates in the overall patient cohort were 20%, 11% and 0% within the high-, moderate-, and standard-risk groups, respectively. The mean length of time from diagnosis to death was 1.3 years. <h3>Conclusion:</h3> The association between IIM and cancer is well established. The published guideline by the International Myositis Assessment and Clinical Studies Group<sup>1</sup> provides clear recommendations for risk stratification and investigative screening of IIM patients. This audit identified an opportunity to enhance the breadth and depth of cancer screening, both at diagnosis and beyond, in line with the published guidance. Active cancer often leads to treatment-refractory IIM, therefore earlier identification and treatment of cancer is likely to positively influence outcomes in IIM. <h3>REFERENCES:</h3> [1] Oldroyd, A.G.S., Callen, J.P., Chinoy, H. <i>et al.</i> International Guideline for Idiopathic Inflammatory Myopathy-Associated Cancer Screening: an International Myositis Assessment and Clinical Studies Group (IMACS) initiative. <i>Nat Rev Rheumatol</i><b>19</b>, 805–817 (2023). <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>