Background and purpose: Tobacco smoking was prognostic in B-cell lymphomas in the pre-rituximab era, but the association with modern treatment, stage, subtypes, and survival outcomes remains unclear.

Patient/material and methods: All patients with diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) from Turku and Tampere University Hospitals 2009–2019 were identified. Population-based data from electronic medical records included demographics, tumour histology, Ann Arbor staging, and treatments. Smoking status was extracted with a deep learning-based natural language processing algorithm. Kaplan–Meier overall survival (OS) estimates and adjusted hazard ratios (HRs) were calculated.

Results: With a median follow-up of 96 months, 1,258 patients with DLBCL and 529 with FL were included. In DLBCL, the 5-year OS rate was 61%, 53%, and 45% among never, former, and persistent smokers, respectively. Persistent smoking remained an independent prognostic factor for shorter OS, HR 1.27 (95% confidence interval 1.10–1.60) after adjustment for comorbidities and completed treatment. The prognosis of FL was indolent with no difference in OS regardless of smoking status, with 5-year OS rates of 79%, 75%, and 74% among never, former, and persistent smokers, respectively. Smokers were younger at diagnosis, while other baseline demographics were similar. No differences in the systemic therapy use were observed between the different smoking categories in both FL and DLBCL.

Interpretation: Overall and lymphoma-specific mortality is increased in persistent smokers with DLBCL compared with never smokers. Smoking prevention and cessation support remains of utmost importance.