The impact of diagnostic wait time on the survival of patients with diffuse large B-cell lymphoma: effect modification by the International Prognostic Index

Despite the importance of a prompt diagnosis to improve cancer patients' survival, little has been reported on diagnostic delay in diffuse large B-cell lymphoma (DLBCL). A single-centre, retrospective study was conducted to examine the association between diagnostic wait time (DWT), the interval from the initial hospital visit to diagnosis, and survival in patients with DLBCL. A total of 193 patients were enrolled from 2007 to 2017 in our institution. A covariate-adjusted Cox proportional hazards model with restricted cubic spline was used to evaluate the impact of DWT on survival, with a subgroup analysis according to the International Prognostic Index (IPI). DWT was not associated with survival in the entire DLBCL population, but the impact of DWT on survival differed between IPI < 3 and >= 3; prolongation of DWT steadily exacerbated the prognosis in patients with IPI >= 3, whereas there was a patient population with IPI < 3 who had a high mortality rate despite rather early diagnosis. The opposite trend in the effect of DWT on survival between patients with IPI < 3 and >= 3 offset survival in all DLBCL patients. DWT had no observable impact on outcomes in the entire DLBCL population, but longer DWT worsened the prognosis, particularly in patients with IPI >= 3.