Patients with chronic lymphocytic leukemia (CLL) who have insufficient levels of vitamin D at the time of diagnosis are at greater risk of cancer progression and death than patients with adequate levels, Mayo Clinic researchers have found.
The findings, published online in Blood, suggest a potential way to slow disease progression. "It appears vitamin D levels may be a modifiable risk factor for leukemia progression,” said lead author Tait Shanafelt, MD, of the Mayo Clinic, Rochester, Minnesota. “It is simple for patients to have their vitamin D levels checked by their physicians with a blood test, and if they are deficient, vitamin D supplements are widely available and have minimal side effects."
The researchers evaluated the relationship between plasma concentrations of 25-hydroxyl-vitamin D with time-to-treatment and overall survival in 390 patients with newly diagnosed CLL who were participating in a prospective, observational study. Of these patients,119 (30.5%) were found to have insufficient vitamin D levels (ie, <25 ng/mL).
After a median follow-up of 3 years, CLL patients deficient in vitamin D were 66% percent more likely to progress and require chemotherapy and twice as likely to die as patients with sufficient vitamin D levels.
To confirm these findings, the researchers then studied a group of 153 untreated CLL patients participating in an observational study who had been followed for an average of 10 years. About 40% these patients were vitamin D deficient at the time of their diagnosis. In this cohort too, patients with vitamin D deficiency were significantly more likely to have had their leukemia progress and to have died than those with adequate vitamin D levels.
This research adds to the growing body of evidence that vitamin D deficiency is a risk factor for development and/or progression of a number of cancers, the researchers say. Studies have suggested that low blood vitamin D levels may be associated with increased incidence of colorectal, breast, and other solid cancers. Other studies have suggested that low vitamin D levels at diagnosis may be associated with poorer outcomes in colorectal, breast, melanoma, and lung cancers, as well as lymphoma.
The researchers are planning a study to determine whether vitamin D replacement in CLL patients with initially low levels will reverse the more rapid progression associated with insufficiency.