Evaluating secondary cancer risk among patients receiving extracorporeal photopheresis for treatment of cutaneous T-cell lymphoma and/or graft versus host disease

Summary: Abstract Body: Extracorporeal photopheresis (ECP) is an effective immunomodulatory therapy used to treat refractory cutaneous T-cell lymphoma (CTCL) and graft-versus-host disease (GVHD). While ECP is thought to have an improved safety profile compared to systemic immunosuppressants, the impact of ECP on long-term cancer risk remains understudied. We aim to evaluate the association between ECP used for treatment of CTCL and/or GVHD and secondary malignancies. Using the multi-institutional TriNetX database, two propensity score-matched cohorts of adult patients with CTCL and/or GVHD were established: those receiving ECP (N=3,244) and those not receiving ECP (N=3,244). Cancer risk and outcomes were evaluated using risk ratios (RR) and Kaplan-Meier survival analyses over a 20-year period. In comparing the cohorts, treatment of CTCL or GVHD with ECP was associated with a higher risk of developing secondary leukemia (RR=1.667, 95% CI: 1.428-1.945, p<0.001) and skin cancer (RR=1.256, 95% CI: 1.101-1.432, p=0.001). Kaplan-Meier analysis revealed significantly lower survival probabilities in ECP patients with secondary leukemias (ECP: 81.55% vs. No ECP:89.48%, p<0.001) and skin cancers (ECP:72.36% vs. No ECP:76.20%, p<0.001). Conversely, ECP was significantly associated with reduced risk for liver (RR=0.081, 95% CI: 0.043-0.155, p<0.001) and pancreatic cancers (RR=0.429, 95% CI: 0.218-0.841, p=0.011). Survival probabilities were also improved in ECP patients with both secondary liver (ECP:99.15% vs. No ECP:93.92%, p<0.001) and pancreatic cancers (ECP:99.22% vs No ECP:98.25%, p=0.015). While ECP therapy is considered an effective treatment for CTCL and GVHD, it may influence patients’ likelihood of developing secondary malignancies, particularly leukemia and skin cancer. CTCL ECP guidelines may need to be updated to reflect these risks, and long-term surveillance strategies should be developed for ECP-treated populations. Abigail Fleischli¹, Sarem Rashid¹, Tara McCaffrey¹, Sima Rozati¹ 1. Dermatology, Johns Hopkins Medicine, Baltimore, MD, United States. Clinical Research: Epidemiology and Observational Research