Background/Purpose:

In psoriatic arthritis (PsA), misdirected inflammation and therapeutic use of immunosuppressants causes global immune compromise. Similar immunocompromised states, as in rheumatoid arthritis and psoriasis patients, have resulted in an increased risk of malignancy. The aim of our study was to compare the development of malignancy in patients with PsA to comparators without PsA.

Methods:

A geographically well-defined population based cohort of 217 patients diagnosed with PsA was identified by individual medical record review. Cases were classified according to the ClASsification Criteria for Psoriatic ARthritis (CASPAR) criteria. Medical records of 217 PsA cases and a comparison cohort of 271 age and sex matched subjects from the same source population were evaluated retrospectively for cancer occurrence. Patients in both cohorts were followed until death, migration from the geographic area or 12/31/2014. Malignancy information was retrieved from the institutional Cancer Registry data to determine prevalence of most major malignancy types. Information concerning non-melanoma skin cancer incidence was collected manually. Cumulative incidence of malignancy adjusted for competing risk of death was used for malignancy incidence analysis. Cohort comparisons were performed using Gray’s test.

Results:

The PsA and non-PsA cohorts (mean age at incidence/index date: 44.0 [SD: 14.2] years; 60% male in both cohorts) were followed on average 15.3 (SD 9.4) and 15.9 (SD 8.6) years, respectively. Prior to PsA incidence/index date, 8 patients with PsA and 15 non-PsA subjects had malignancies (p=0.20). During follow-up, a total of 28 malignancies were detected in the patients with PsA (cumulative incidence at 10 years after PsA incidence: 9.3% [SE 2.2%}), and 41 malignancies were diagnosed in the comparator subjects, representing no statistical difference in malignancy incidence (cumulative incidence at 10 years after index date: 9.4% [SE 2.2%], p=0.21). The relative risk of most individual malignancies was not statistically increased in the PsA cohort compared to the non-PsA cohort.  There were more non-melanoma skin cancers in the PsA cohort (n=23 compared to 14 in the comparator cohort) although the difference did not reaching statistical significance (p= 0.09).  

Conclusion:

The risk of cancer in this population based cohort of patients with PsA is not increased compared to the general population. This finding is consistent with several other studies employing other methodologies. There were numerically more non-melanoma skin cancers in the PsA cohort, which may be related to the generally increased risk of these cancers seen in psoriasis.  We suggest that patients with PsA should be routinely screened for occurrence of these skin cancers.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/malignancies-in-patients-with-incident-psoriatic-arthritis-1970-2008-in-relation-to-a-comparator-cohort-a-population-based-case-control-study/