Vitamin D insufficiency predicts time to first treatment (TFT) in early chronic lymphocytic leukemia (CLL)

Although vitamin D insufficiency is related to inferior prognosis in some cancers, limited data exist in hematologic malignancies. We evaluated the relationship between 25(OH)D serum levels and time to first treatment (TFT), a disease-specific end point, in 130 previously untreated Binet stage A chronic lymphocytic leukemia (CLL) patients. Measurement of 25(OH)D was performed by means of a direct, competitive chemiluminescence immunoassay using the DiaSorin LIAISON 25(OH)D TOTAL assay (DiaSorin, Inc., Stillwater, Minnesota). Overall, 41 patients (31.5%) had severe vitamin D insufficiency (<10 ng/mL), 66 (50.7%) had mild to moderate insufficiency (10-24 ng/mL), and 23 (17.6%) had 25(OH)D levels within the optimal range (25-80 ng/mL), with no relationship with between the season of sample collection and 25(OH)D level (P=0.188). A patient stratification according to these 3 groups led to significant difference in terms of TFT, with vitamin D insufficient patients having the shortest TFT (P=0.02). With respect to continuous 25(OH)D levels and clinical outcome, TFT was shorter as 25(OH)D decreased until a value of 13.5 ng/mL at which point the association of 25(OH)D and TFT remained constant. As a matter of fact, the 25(OH)D value of 13.5 ng/mL identified two patients subsets with different TFT risk (HR=1.91; 95% CI=1.06-3.44; P=0.03). In multivariate analysis the variable entering the model at a significant level were mutational status of IgVH (P<0.0001), serum thymidine kinase (P=0.02) and absolute lymphocyte count (P=0.03). Thus confirming the Mayo clinic experience, our data provide further evidence that 25(OH)D levels may be an important host factor influencing TFT of Binet stage A patients. Whether normalizing vitamin D levels may delay disease-progression of patients with early disease will require testing in future trials.