According to data presented at this year’s AACR Annual Meeting, vitamin D impacts prostate cancer growth rates and may also decelerate the growth of prostate cancer cells.
“This study shows calcitriol makes the foot come off the gas pedal of cancer growth. We are not able to prove that the speed of the car has slowed down, but it certainly is a good sign,” said Reinhold Vieth, PhD, professor at the University of Toronto in Toronto, Ontario, Canada. “We expect that this early-phase clinical trial will open the door for more detailed clinical research into the usefulness of vitamin D in the treatment or prevention of prostate cancer.”
For this study, Vieth and colleagues randomly assigned 66 men scheduled for radical prostatectomy to daily doses of vitamin D (400, 10,000 or 40,000 IU) for 3 to 8 weeks before surgery.
Researchers found that calcitriol levels in prostate tissue increased gradually with each daily dose of vitamin D, with 40,000 IU presenting the highest levels. These higher levels of calcitriol corresponded with lower prostate levels of the proliferation marker Ki67, as well as higher levels of cancer growth inhibitory microRNAs.
Vitamin D supplementation in doses higher than 4000 IU daily are not recommended, Vieth emphasized. Patients in the study were assigned to the 40,000 IU daily dose due to the study’s brief presurgical time frame and not as a regular course of therapy.
“Plain vitamin D provides the raw material to permit the body to take care of its own needs,” he said. “We showed here that plain vitamin D allows the prostate to regulate its own level of calcitriol, and at the doses we used, for the time frame we used, it has been safe with the hoped-for desirable outcomes.”
Source: AACR.