Aims Diffuse large B-cell lymphoma (DLBCL) is an aggressive and potentially fatal disease. Prediction of risk of relapse is based on clinical markers. There is a need for more accurate biomarkers to select patients for more aggressive first-line treatments. Peroxiredoxins (Prxs) are a family of potent antioxidant proteins. Their prognostic role in DLBCL is unknown.

Methods Altogether, 103 diagnostic biopsy samples from patients with DLBCL were immunohistochemically stained for Prxs I, II, III, V and VI.

Results Strong Prx VI expression was associated with the presence of B-symptoms. There were no other significant associations with traditional risk factors. Five-year disease-specific survival was 68.6% in patients with high cytoplasmic Prx VI intensity vs 97.0% in those with low intensity. In multivariate analysis, high Prx VI expression (HR 12.846, 95% CI 1.722 to 95.807, p=0.013) was an independent risk factor of lymphoma-associated death not related to International Prognostic Index score (HR 2.514, 95% CI 1.040 to 6.073, p=0.041).

Conclusions High intensity of cytoplasmic Prx VI expression in pretreatment DLBCL samples predicts worse outcome in patients with DLBCL. Whether Prx VI is associated with chemoresistance, and therefore a poorer outcome, needs to be evaluated. If Prx VI is a predictive marker and it proves causality, it would be crucial to study Prx VI ability to become a target enzyme for treatment.