Prognosis of diffuse large B cell lymphoma related to occupational exposure to pesticides: A cohort study

Summary Importance Professional use of pesticides is a risk factor for non-Hodgkin lymphoma. The main biological mechanisms of both pesticides and chemotherapy are genotoxicity and reactive oxygen species generation. Cellular adaptation among patients exposed to low doses of genotoxic and oxidative compounds may hinder chemotherapy efficiency in lymphoma patients. Objective We aim to determine the influence of occupational exposure to pesticides on response to immuno-chemotherapy and survival of patients treated for Diffuse Large B Cell Lymphoma (DLBCL). Design The ProLyPhy study is a retrospective cohort of patients treated between 2010 and mid-2015, for DLBCL, with a least 2-year follow-up. Setting The study took place in six hospitals of central southern France (Languedoc-Roussillon district): two university hospitals, three general hospitals, and one private hospital. Participants We pre-included 404 patients with newly-diagnosed DLBCL treated with anthracycline-based immuno-chemotherapy (R-CHOP like). Occupational history was reconstructed for 244 patients. Occupational data were analysed with the Pestipop French job-exposure matrix to determine probability of occupational exposure to pesticides, and with the Pestimat French crop exposure matrix for farming activities to characterise the probability of using specific compounds. Main outcome and measure We have compared complete response (CR), 2-year event-free survival (EFS) and overall survival (OS) of exposed and non-exposed patients, after adjustment on confounding factors. Results Average age was 61.3 years (range 19–90), 62.7% of patients were male, 67 had occupational exposure to pesticides, of which 38 from farming activities. Occupational exposure did not impact clinical and biological characteristics at diagnostic. We observed that exposed patients had significantly lower CR rate: 77.6% versus 88.7% (P = 0.027), OR = 0.31 (0.55–0.09, P = 0.007); this difference was higher among farmers: 68.6% CR versus 87.2%, P = 0.005, OR = 0.22 (0.56–0.09, P = 0.001). Two-year EFS was 70% in the occupationally-exposed group versus 82%, HR = 2.1 (95% CI: 1.2–3.6, P = 0.008). Among farmers, the difference was more pronounced: 2-year EFS was 56% versus 83%, HR = 3.1 (95% CI: 1.7–5.6, P Conclusion and relevance This retrospective study suggests that agricultural occupational exposure to pesticides is an independent risk factor for treatment failure, EFS and OS in DLBCL. Trial registration The study was registered in ClinicalTrials.gov ( NCT02898870 ).