Time to lymphoma treatment within 24 months in ‘watch and wait’ follicular lymphoma is associated with inferior outcomes: A multicentre analysis

Some 'watch and wait' (W&W) FL patients suffer from rapid progression in a short term. Herein, we sought to identify these patients and also develop a risk score to screen them at diagnosis. Between 2008 and 2022, a total of 411 FL patients managed by the W&W strategy from 16 cancer centres were retrospectively enrolled in this study, and their time to lymphoma treatment (TLT) and progression-free survival (PFS) were evaluated. Thirty-five percent of W&W FL patients experienced TLT within 24 months (TLT24) after diagnosis. Their 5-year PFS rate was significantly lower than those without treatment at 24 months (62.3% vs. 89.5%). In multivariable analysis, five factors were identified as independent predictors of TLT24: stages III-IV, β₂ microglobulin ≥3 mg/L, lymphocyte-to-monocyte ratio <3.8, bone marrow involvement and spleen enlargement (above umbilical line). Their AUCs for TLT24 were 0.76 (95% CI, 0.70-0.82) in the training cohort and 0.76 (95% CI, 0.67-0.85) in the validation cohort respectively. Risk groups were also associated with PFS (p < 0.001). In FL patients initially managed by W&W, TLT24 was associated with poor outcomes. This multivariable model helps screening for predicting TLT24, which may be useful to identify candidates for early interventional treatment.