A prospective trial among breast cancer patients enrolled in The Pathways Study has found that higher levels of vitamin D can lower the risk of breast cancer morbidity and mortality.
Vitamin D can improve prognosis and overall survival (OS) in women being treated for breast cancer. These results, gathered from a study being led by researchers at the Roswell Park Cancer Institute and Kaiser Permanente, were published in JAMA Oncology.
Nutritional deficits are known to impact susceptibility to various diseases, including cancer, and vitamin D in particular has been the subject of several studies evaluating its association with cancer progression. While previous studies have shown an increased risk of breast cancer recurrence at distant sites and death in patients with vitamin D deficiency, the results remain controversial with some other studies negating the association.
Participants in the current trial were a part of The Pathways Study, established in 2006 within the integrated care delivery system of Kaiser Permanente Northern California. The trial documented a nearly 50% enrollment rate—enrollment halted in 2013, but follow-up continues, with milestones set at 12, 24, 48, 72, and 96 months after baseline interview. The trial, which used 25-hydroxyvitamin D (25OHD) as a surrogate readout for levels of vitamin D in the serum, used a case-cohort design for efficiency assay of 25OHD. Primary trial outcomes include breast cancer recurrence, second primary cancer, and death.
Data analysis showed that women with more advanced cancer had lower concentrations of serum 25OHD, with the lowest levels observed in premenopausal women with triple negative breast cancer. Further, levels of 25OHD inversely correlated with hazards of disease progression and death, the authors wrote—women with the highest tertile of 25OHD expression surviving the longest, following adjustment for clinical prognostic factors (hazard ratio [HR], 0.72; 95% CI, 0.54-0.98). Premenopausal women displayed the strongest association with OS (HR, 0.45; 95% CI, 0.21-0.96).
Based on their findings, the authors concluded that serum 25OHD levels are associated with patient prognosis in breast cancer, particularly among premenopausal women, and that higher levels of vitamin D can lower the risk breast cancer morbidity and mortality.
“This large prospective observational study provides compelling evidence that higher levels of vitamin D at the time of breast cancer diagnosis can reduce the risk of breast cancer progression and death,” Song Yao, PhD, associate professor of oncology in the Department of Cancer Prevention and Control at Roswell Park and first author on the study, said in a statement.
Yao S, Kwan ML, Ergas IJ, et al. Association of serum level of vitamin D at diagnosis with breast cancer survival: a case-cohort analysis in the pathways study [published online November 10, 2016]. JAMA Oncol. doi: 10.1001/jamaoncol.2016.4188.