A new study has shown that there may be a link between higher vitamin D levels and longer breast cancer survival. The report is promising news for the millions of people worldwide affected by this disease.
Breast cancer is the most common cancer for women worldwide, with nearly 1.7 million new cases diagnosed in 2012. This represents about 12% of all new cancer cases and 25% of all cancers in women.
In Australia, it is estimated that in 2015, 15,600 women and 145 men were diagnosed with breast cancer. In New Zealand, 3,000 women and 20 men are diagnosed each year.
The study, conducted by Jama Oncology, examined 1666 women with breast cancer to determine whether there was an association between vitamin D levels at the time of diagnosis with breast cancer survival.
The report found that out of those women tested, higher levels of vitamin D were independently associated with better outcomes, including overall survival. Compared with women whose vitamin D levels are under 17 nanograms per millilitre, women with levels higher than 25 had a 28 per cent higher likelihood of surviving over the course of the study, even after adjusting for many factors, including tumour stage, grade and type.
What’s more, the study showed a particularly strong correlation between vitamin D and better health for premenopausal women. The authors conclude that this study provides compelling observational evidence on associations of vitamin D with lower risk of breast cancer morbidity and mortality.
However, it is important to note that whilst these reports are promising, this is not a clinical trial and so causality cannot be clearly established. Song Yao, the lead author of the study and an associate professor at the Roswell Park Cancer Institute in Buffalo NY recommends approaching these results with caution, “We cannot say with 100 per cent certainty that vitamin D can improve breast cancer survival”.
Given that an estimated 31% of adults in Australia have inadequate vitamin D status (this figure increases to more than 50% of women in winter) considering an increase of vitamin D intake makes good health sense. For many people, the main source of vitamin D comes from sun exposure. You can read more about vitamin D guidelines for Australia and New Zealand here