The VITAL study generated a host of questions about vitamin D among ASCO Annual Meeting attendees, including whether the study’s findings are ready for clinical application, according to Debra L. Barton, RN, PhD, of the Mayo Clinic, Rochester, Minnesota, speaking at the Best of ASCO San Diego meeting.

There are reasons to think about vitamin D beyond preventing musculoskeletal pain, such as maintaining bone health and preventing falls, she contended. “We already know that a lot of patients treated for breast cancer are deficient in vitamin D based on other, descriptive studies.… And we know that older folks are at risk for decreases in vitamin D anyway. So you put all those things together … and it is worth taking a look at.”

Additionally, it is imperative that women be able to stay on aromatase inhibitors to minimize their risk of breast cancer recurrence. “If you have a patient who is just not getting good enough relief from her symptoms, and she is thinking about quitting her letrozole or whatever aromatase inhibitor she’s on, it’s certainly worth it, based on this study” to consider supplementation.

Dosage Considerations

“I was extremely disappointed when the Institute of Medicine revisited the vitamin D supplementation data and didn’t really change their recommendation,” Dr. Barton commented. “Now, 400 IU of vitamin D per day only changes vitamin D levels by 2 to 3 ng/mL, so if somebody is deficient, it’s not going to do much. It really takes about a 1,000 IU per day to change the level by about 10 ng/mL, which is getting somewhere.”

Clearly, the 30,000 IU weekly used in the trial was a very large dose, she acknowledged. “That’s why it would be really nice for the VITAL investigators to repeat that study in a cooperative group setting and give us some very good, clear guidelines on when that’s necessary, or when we should be doing that,” she concluded. “We are obviously not going to do that for everybody right now. But I will say, I encourage everybody I speak with to take 1,000 IU a day.” ■