Background/Purpose: Anti-transcription intermediary factor 1-gamma autoantibody (anti-TIF-1ƴ Ab) associated dermatomyositis (DM) is strongly associated with the occurrence of malignancies. Patients may develop cancers prior to, concurrent with, or at a period after the diagnosis of DM. Close surveillance for cancer has been advocated for this group to allow early detection and cure of the underlying malignancy. The objective of this study was to determine the clinical profile and outcomes of anti-TIF-1ƴ positive DM patients in Singapore.

Methods: A chart review was undertaken of 79 DM patients with positive myositis specific antibodies diagnosed between January 2015 and July 2019 at a major tertiary hospital in Singapore. All patients included fulfilled the Bohan/ Peter criteria for probable/ definite DM and had International Myositis Classification Criteria scores of at least 55% consistent with probable idiopathic inflammatory DM.

Results: Of the 79 patients diagnosed with DM, 33 were found to be anti-TIF-1ƴ Ab positive. In the anti-TIF-1ƴ Ab positive group, 69.7% were female, 15.2% were smokers, and the median age of DM diagnosis was 61 years.  A higher proportion of the anti-TIF-1ƴ Ab positive group (57.6%) developed cancer compared to the anti-TIF-1ƴ Ab negative group (8.7%).

The median time interval to diagnosis of malignancy in the cancer associated anti-TIF-1ƴ Ab positive DM group was 12 months prior to or 12 months following the onset of DM. In the cancer associated anti-TIF-1ƴ Ab positive group, DM was diagnosed before cancer in 26.3 % of patients, cancer before DM in 36.8 % and both cancer and DM diagnosed at the same time in 36.8 %. In those anti-TIF-1ƴ Ab negative DM patients that developed cancer, the cancer was either diagnosed prior or concurrently with DM.

Nasopharyngeal carcinoma (NPC) was the commonest cancer (31.6%) in the anti-TIF-1ƴ Ab positive DM group, followed by breast (21.1%), bowel (15.8%), lung (10.5%), cervical/ovarian (5.3%), lymphoma (5.3%), thyroid (5.3%), and kidney (5.3%). Of these patients 35% died, 60% improved and remained stable, and 5% sustained a relapse. Of those anti-TIF-1ƴ Ab positive NPC, 66.6% presented with advanced stage (Stage III or more) and all had undifferentiated histology.

Conclusion: Our results show the strong association of anti-TIF-1ƴ Ab DM and increased risk of malignancy, particularly nasopharyngeal cancer in our Singaporean population. The cancer associated anti-TIF-1ƴ Ab DM patients developed cancer within a year prior to or following the onset of DM and had a worse prognosis than the anti-TIF-1ƴ Ab negative group. The clinical profile revealed in this review will be useful in guiding the targeted cancer surveillance needed for this group of patients to reduce morbidity and mortality.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/characteristics-of-anti-transcription-intermediary-factor-1-gamma-autoantibody-positive-dermatomyositis-patients-in-singapore/