Background/Purpose: An association between cancer and dermatomyositis (DM), referred to as cancer-associated myositis, is well recognized and clinically important. The overall cancer risk is up to 25-30% among DM patients. The high frequency of malignancies detected close to DM diagnosis suggests that DM can be a paraneoplastic syndrome, and cancer within three years of DM diagnosis is often defined as cancer associated myositis (CAM). The absence of a biomarker for CAM leads to a thorough screening for cancer in patients diagnosed with DM. Recently anti-TIF1-gamma has been discovered to be associated with cancer and DM. A meta-analysis claimed pooled sensitivity of anti-TIF1-gamma for diagnosing cancer-associated DM to be 78% (95% CI 45–94%), and specificity to be 89% (95% CI 82–93%). Thus anti-TIF1-gamma has shown promising results as a marker for CAM. However, none of the studies evaluated anti-TIF1-gamma association with cancer with or without other paraneoplastic rheumatic syndrome than DM. To clarify the specificity of anti-TIF1-gamma antibodies as a biomarker for CAM we analyzed the frequency of anti-TIF1-gamma antibodies in other cancer associated inflammatory rheumatic syndromes as well as in cancer patients and healthy controls.

Methods:  Sera from patients with paraneoplastic rheumatic syndrome (n=91) (arthritis n=39, Raynaud´s n=23, other n=29) , patients with solid cancer (n=95) and healthy controls (n=80) were analyzed for the frequency of anti-TIF1-gamma IgG by ELISA using a commercially available recombinant TIF1-gamma protein as coating antigen. The cut-off value was calculated by adding 2SD to the mean OD value of 80 healthy controls.

Results:  Positivity for anti-TIF1-gamma IgG was 3,3% (n=3) in patients with paraneoplastic rheumatic syndrome, 3,1% (n=3) in cancer patients and 1,3% (n=1) in healthy controls. There was no significant difference in positivity between the groups (p>0,05). Sensitivity and specificity for diagnosing cancer were 3,2% and 98,7%, and for paraneoplastic rheumatic syndromes, 3,3% and 96,84% respectively.

Conclusion:  AntiTIF1-gamma antibodies are rarely present in patients with solid cancers or paraneoplastic rheumatic syndromes. This finding strengthens the approach to use anti-TIF1-gamma IgG as marker for cancer-associated DM.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/anti-tif1-gamma-antibodies-are-not-associated-with-other-paraneoplastic-rheumatic-syndromes-than-dermatomyositis/