Incidence rates of malignancy and precancerous lesions in Newfoundland and Labrador population with immune mediated inflammatory diseases: psoriatic arthritis and rheumathoid arthritis

Lewis, Alyona F. (2018) Incidence rates of malignancy and precancerous lesions in Newfoundland and Labrador population with immune mediated inflammatory diseases: psoriatic arthritis and rheumathoid arthritis. Masters thesis, Memorial University of Newfoundland.

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Abstract

Background: Rheumatoid Arthritis (RA) and Psoriatic Arthritis (PsA) are reported to be associated with an increased risk of malignancy. Newfoundland and Labrador (NL) has one of the highest cancer rates in Canada. There is a paucity of literature on the prevalence of malignancy in NL patients diagnosed with RA and PsA. We hypothesize that the risk of malignancy in these groups of patients is higher compared to the NL general population. Objective: Evaluate the incidence of malignancy and precancerous lesions in a cohort of PsA and RA patients and compare rates with the general population. Evaluate the impact of therapy and chronic inflammation on these two diseases. Methods: Data were extracted from the charts of 700 arthritis patients (68% female) seen at a local rheumatology clinic between 2011 and 2014. Statistical analyses were performed using SPSS v. 21.0 (IBM Inc.). Overall cancer incidence rates were calculated per 100,000 person-years. Observed rates were compared with the rates in the NL general population. Multivariate regression analysis was used to assess association between incident cancers and explanatory variables. Result: The results suggest no significant difference in cancer rates between the cohort and the NL general population (P<0.3217). We identified 37(5.3%) different types of cancers. Etanercept and combination therapy (Biologics (bDMARDs) and Methotrexate (MTX)) showed significant risk reduction: (OR=0.1, 95% CI, 0.01-0.89, P=0.039) and (OR=0.3, 95% CI, 0.02-0.44, P=0.003) respectively. Conclusion: There is no difference in the cancer rate between our study and the NL general population. We also concluded that the analyzed data was reassuring due to OR values less than 1 (OR 0.3, P=0.003) for combined therapy of MTX and Biologics. More epidemiologic studies are required to determine the cancer prevalence in NL population.

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