Comment on: The temporal relationship between cancer and adult onset anti-transcriptional intermediary factor 1 antibody–positive dermatomyositis: Reply

Objectives To characterise the 10 year relationship between anti-transcriptional intermediary factor 1 antibody (anti-TIF1-Ab) positivity and cancer onset in a large UK-based adult dermatomyositis (DM) cohort. Methods Data from anti-TIF1-Ab positive/negative adults with verified diagnoses of DM from UKMYONET were analysed. Each patient was followed up until they developed cancer. Kaplan-Meier methods and Cox-proportional hazard modelling were employed to estimate cumulative cancer incidence. Results Data from 263 DM cases were analysed, with a total of 3,252 person-years and a median 11 years follow-up; 55 (21%) of DM cases were anti-TIF1-Ab positive. After 10 years of follow up, a higher proportion of anti-TIF1-Ab positive cases developed cancer, compared with anti-TIF1-Ab negative cases: 38% vs 15% (hazard ratio 3.4 [95% CI 2.2, 5.4]). All the detected malignancy cases in the anti-TIF1-Ab positive cohort occurred between 3 years prior to and 2.5 years after DM onset. No cancer cases were detected within the following 7.5 years in this group, whereas cancers were detected during this period in the anti-TIF1-Ab negative cases. Ovarian cancer was more common in the anti-TIF1-Ab positive vs negative cohort – 19% versus 2% respectively (p-value <0.05). No anti-TIF1-Ab positive case aged under 39 years developed cancer, compared to 21 (53%) of those aged 39 years and over. Conclusion Anti-TIF1-Ab positive-associated malignancy occurs exclusively within the three year period either side of DM onset, the risk being highest in those aged 39 years and over. Cancer types differ according to anti-TIF1-Ab status, and this may warrant specific cancer screening approaches.