Vitamin D supplement for patients with early-stage chronic lymphocytic leukemia is associated with a longer time to first treatment.

Low levels of vitamin D are associated with a shorter time to first treatment (TTFT) and inferior overall survival in patients with chronic lymphocytic leukemia (CLL). But whether vitamin D supplement affects the clinical course of patients with CLL, remains an open question. In this study, we aimed to retrospectively explore the clinical benefit of vitamin D supplement or one of its analogs, on TTFT and treatment-free survival (TFS) in a large cohort of patients with asymptomatic CLL, who were under watch-and-wait approach. Among the 3474 patients included in the study, 931 patients (26.8%) received either vitamin D supplement or its analog, for a minimum of 6 months. We found that vitamin D supplement was statistically significant for longer TTFT in the young cohort (age ≤65) and was associated with a longer TFS for all ages (P = .004). Among non-vitamin-D users, the median TFS was found to be 84 months, whereas among vitamin D supplement users the median TFS extended to 169 months. In conclusion, our long-term retrospective study demonstrates that the administration of vitamin D to patients with CLL in a watch-and-wait active surveillance is significantly associated with a longer TFS (in any age) and a longer TTFT among young patients (age ≤65). A prospective clinical trial is needed to validate results.