Background/Purpose: The idiopathic inflammatory myopathies (IIMs) are strongly associated with the development of clinically detectable cancer. Cancer screening has therefore been advocated in newly diagnosed IIM cases, however no study has investigated if this confers improved long term survival. This study aimed to investigate if a shorter time between IIM onset and cancer diagnosis is associated with improved long term survival.

Methods: Adult IIM cases (dermatomyositis, polymyositis and anti-synthetase syndrome) were recruited from four separate cohort studies from the UK, France, Czechia and Hungary.

Only cases with cancer diagnosis following IIM onset were included in analysis (i.e. synchronous cancer cases were excluded). The time between IIM onset and cancer diagnosis was calculated for each case. Where death occurred, the time between cancer diagnosis and death was calculated and employed as follow up time. Where death did not occur, the time between cancer diagnosis and their follow up cut-off date was calculated. Cases were censored at the end of their follow up period if death did not occur. The relationship between survival at the end of follow up and time between IIM onset and cancer diagnosis was quantified via calculation of hazard ratios using a Cox-proportional hazard model adjusted for age and gender.

Results: A total of 248 (68% female) verified IIM cases with a total of 1,601 person-years follow up (median 5.1 years [IQR 1.7, 8.9]) were included in the analysis (Table 1).

Sixty deaths occurred within the follow up period in the whole cohort. The median time between cancer diagnosis and death was 2 years (IQR 0.3, 5.3). The IIM to cancer diagnosis time was shorter for those that survived at the end of follow up, compared to those that died: 4.5 years (IQR 1.0, 10.2), 5.5 years (IQR 1.5, 13.6), respectively. Deaths in the male cohort occurred earlier after cancer diagnosis than in the female cohort: 1 year vs 2.4 years.

Cox-proportional hazard modelling indicated that a longer IIM onset to cancer diagnosis time was significantly associated with death for the whole cohort (HR 1.04 [95% CI 1.01, 1.06], p-value < 0.01) (Figure 1). This relationship persisted after adjustment for age and gender (HR 1.05 [95% CI 1.01, 1.08], p-value < 0.01). However, this relationship was observed in the female cohort only (HR 1.05 [95% CI 1.01, 1.08], p-value < 0.01) and not the male cohort (HR 1.05 [95% CI 0.97, 1.13], p-value 0.26).

Conclusion: This is the first study to identify that earlier cancer diagnosis after IIM onset is associated with improved long term survival in a large cohort, comprising UK, French, Czechia and Hungarian cases. However, this relationship was only significant for the female cohort. These findings indicate that cancer screening in newly diagnosed IIM cases may confer improved survival, especially in female cases.

Table 1 – Time to cancer diagnosis and death for the whole cohort, divided by gender

Figure 1 – Modelling results of relationship between survival and time between IIM onset and cancer diagnosis, divided by gender. HR = hazard ratio. CI = confidence interval. † Hazard ratio for survival – adjusted for age and gender. * Hazard ratio for survival – adjusted for age.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/earlier-cancer-diagnosis-after-idiopathic-inflammatory-myopathy-onset-is-associated-with-improved-long-term-survival-results-from-four-european-cohorts/