Objective: An association between cancer and dermatomyositis (DM) is well recognized. The high frequency of malignancies detected close to DM diagnosis suggest that DM can be a paraneoplastic syndrome. Recently, anti-transcription intermediary factor 1γ (anti-TIF1γ) has been discovered to be associated with cancer and with DM. A meta-analysis reported the pooled sensitivity of anti-p155 for diagnosing cancer-associated DM to be 78% and the specificity to be 89%. Thus, anti-TIF1γ has shown promising results as a marker for cancer-associated DM. However, none of the studies evaluated the association of anti-TIF1γ with cancer with or without rheumatic diseases other than DM. To clarify the specificity of anti-TIF1γ antibodies as a biomarker for cancer-associated DM, we analyzed the frequency of anti-TIF1γ antibodies in other cancer-associated rheumatic syndromes, as well as in cancer patients and healthy controls.
Methods: Sera from patients with paraneoplastic rheumatic syndrome (n = 91), patients with solid cancer (n = 95), and healthy controls (n = 80) were analyzed for the frequency of anti-TIF1γ IgG by enzyme-linked immunosorbent assay using a commercially available recombinant TIF1γ protein as coating antigen. The cutoff value was calculated by adding 2 SD to the mean optical density value of 80 healthy controls.
Results: The rate of anti-TIF1γ IgG positivity 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 were no significant differences in positivity between the groups (P < 0.05).
Conclusion: Anti-TIF1γ antibodies are rarely present in patients with solid cancers or paraneoplastic rheumatic syndromes. This finding strengthens the approach to using anti-TIF1γ IgG as a marker for cancer-associated DM.
© 2017, American College of Rheumatology.