Risk of cancer in patients with psoriasis on biological therapies: a systematic review

Background Biological therapies are highly effective in psoriasis, but have profound effects on innate and adaptive immune pathways that may negatively impact on cancer immunosurveillance mechanisms. Objectives To investigate the risk of cancer in patients with psoriasis treated with biological therapy. Methods We searched MEDLINE, Embase, and the Cochrane Library (up to August 2016) for randomized controlled trials, prospective cohort studies and systematic reviews that reported cancer incidence in people exposed to biological therapy for psoriasis compared with a control population. Results Eight prospective cohort studies met our inclusion criteria. All the evidence reviewed related to tumour necrosis factor inhibitors (TNFi) with the exception of one study on ustekinumab. An increased risk of nonmelanoma skin cancer (NMSC), particularly squamous cell carcinoma, was reported with TNFi compared with both a general United States population and a rheumatoid arthritis population treated with TNFi. No evidence for increased risk of cancers (reported as all cancers, lymphoma, melanoma, prostate, colorectal and breast cancer) other than NMSC was identified. Conclusions There were important limitations to the studies identified including choice of comparator arms, inadequate adjustment for confounding factors and failure to account for latency periods of cancer. There remains a need for ongoing pharmacovigilance in relation to cancer risk and biological therapy; the NMSC signal requires further investigation to determine the risk specifically attributable to biological therapy using prospectively collected data with adjustment for known NMSC risk factors.