Another major article showing the relationship between vitamin D level and breast cancer prognosis has just been published. This was a study which is called a “Meta ‚Äì analysis”. This is the type of study that reviews several other articles and then summarizes and integrates their findings.
In this study the researchers looked for studies that obtained vitamin D levels at the time of non-‚Äìmetastatic breast cancer diagnosis and then measured the clinical outcomes of recurrence, distant recurrence, death and breast cancer specific death.
Researchers found eight studies that met their criteria for inclusion, and that included 5691 patients.
The findings of this study were:
1. All six of the studies found that vitamin D deficiency is associated with an increased risk of breast cancer recurrence.
2. When the studies were brought together there was a 2.13 times increased associated risk of having a breast cancer recurrence if the patient was vitamin D deficient compared to having enough vitamin D.
3. All six of the studies found that vitamin D deficiency was associated with an increased risk of death.
4. When the studies were all brought together there was a 1.76 times increased associated risk of death if the patient was vitamin D deficient compared to those who were sufficient.
The researchers concluded “We have identified statistically significant associations of low levels of vitamin D, measured around the time of breast cancer diagnosis, with an increased risk of recurrence and death in early-stage breast cancer patients.”
Researchers pointed out, as I’ve pointed out in my book and in my lectures, that these studies are still “observational”, and therefore cannot come to a 100% conclusion that there is a *causal connection* between vitamin D deficiency and a risk of recurrence and death from breast cancer.
The study that needs to be done to prove the direct relationship between vitamin D and breast cancer would be a double-blind crossover placebo study. In this study one group of women with breast cancer would get the vitamin D and the other group would not. They would then be followed over 5 to 10 years to see which ones died.
The obvious problem with such a study in this day and age with the Internet, is that women with breast cancer often begin taking vitamin D themselves even though their oncologists are not prescribing it. This is a good thing but therefore would make this type of study very difficult to run.
My position remains the same as it has been since I wrote my book. Since there is no harm in normalizing one’s vitamin D blood level, everybody including women who have been diagnosed with breast cancer, should do that.
If the double-blind placebo-controlled trials which will come out in the next 10 years do prove there was be a benefit,(they will) then we all got the benefit early and this may prevent a disease in us. If it shows no benefit, there has been no harm in normalizing our vitamin D level.
At this time of year, Thanksgiving and Christmas, when most of our country is in what we call the “Vitamin D Winter”, have you checked your blood level of vitamin D recently? Are you taking vitamin D? Are you giving it to your children?
Here is a nice interview with Dr. David Feldman, Professor Emeritus, Medicine Endocrinology, Gerontology & Metabolism Stanford University School of Medicine about Vitamin D and its relationship with breast cancer.
This was an interview conducted by Carole Baggerly during the Linus Pauling Institute Conference 2013.
Please let me know your thoughts in the comments below.