08 Jun Study Examines Vitamin D and Cancer Prognosis
MedicalResearch.com Interview with:
Adetunji Toriola, MD, PhD, MPH
Assistant Professor Division of Public Health Sciences
Department of Surgery
Washington University School of Medicine
Siteman Cancer Center St. Louis, MO
MedicalResearch: What are the main findings of the study?
Dr. Toriola: Very little is known about the impact of vitamin D in prognosis among cancer patients. This knowledge is of importance because of the increasing number of people living cancer and the high prevalence of vitamin D deficiency among cancer patients. We conducted a systematic review of studies published to date on the association of circulating vitamin D (25-OHD) levels with prognosis among cancer patients. This review suggests that higher circulating vitamin D levels may improve overall survival among breast and colorectal cancer patients but there is paucity of information on the role of circulating vitamin D levels in prognosis among patients with other cancer types.
MedicalResearch: Were any of the findings unexpected?
Dr. Toriola: The findings were not unexpected and are biologically plausible. Experimentally, high vitamin D levels have been shown to suppress tumor progression. Nevertheless, very few human studies have explored this relationship.
MedicalResearch: What should clinicians and patients take away from your report?
Dr. Toriola: For now, we need more studies evaluating the impact of vitamin D on cancer prognosis before any clinical recommendations can be made. This is because there are still many unanswered questions. In addition, most studies have been observational in nature and randomized controlled trials will be needed.
MedicalResearch: What recommendations do you have for future research as a result of this study?
Dr. Toriola: Future studies need to tease out the effect of physical activity on the relationship between circulating vitamin D levels and cancer prognosis. It has been suggested that circulating vitamin D level may just be a marker of physical activity, since physically active people are likely to have a greater exposure to sunlight, which is a major determinant of circulating vitamin D levels, and they also have better prognosis. Further, most studies have evaluated the associations of vitamin D levels in blood samples taken after commencement of chemotherapy, rather than before commencement of chemotherapy. This distention is essential as chemotherapy is known to affect circulating vitamin D levels.