| Abstract: | In aggressive lymphomas, discrepancies in survival reported from experimental and observational studies may reflect selective non‐enrolment of high‐risk patients in trials. We examined the association between time from diagnosis to chemotherapy and overall survival in diffuse large B‐cell (DLBCL), Burkitt (BL), mantle cell (MCL) and peripheral T‐cell lymphoma (PTCL), using National Cancer Data Base records of 130 549 patients treated in 2004–2014. Across the histologies, patients who started chemotherapy within 7 days of diagnosis had more often high International Prognostic Index (IPI) or advanced‐stage disease. The discrepancy in 3‐year survival between groups treated within 7 or >30 days from diagnosis ranged from 14% in BL to 30% in MCL. After adjusting for the IPI, time to treatment was significantly associated with shorter overall survival. Using the group treated >30 days from diagnosis as reference, patients treated within 7 days had a hazard ratio of 1·38 [95% confidence interval (CI), 1·28–1·48] in DLBCL, 1·42 (95% CI, 1·22–1·66) in BL, 2·23 (95% CI, 1·79–2·78) in MCL and 1·46 (95% CI, 1·18–1·81) in PTCL. Time from diagnosis to treatment may reflect high‐risk features uncaptured by standard prognostic assessments. Clinical trials should accommodate patients who need urgent therapy to improve external validity and detect treatment effects in high‐risk groups. |
