A recent study published in the American Journal of Clinical Nutrition found that vitamin D status at diagnosis is a predictor of survival among women with ovarian cancer.
Vitamin D affects the action of many genes that regulate cell proliferation and apoptosis (programmed cell death). Thus, researchers suspect that vitamin D plays a role in cancer.
Studies have provided extensive evidence that supports this theory in colorectal, prostate and breast cancer. However, only one small study has evaluated the relationship between vitamin D levels and ovarian cancer.
Ovarian cancer is the fifth leading cause of cancer death among women in the United States, resulting in over 14,000 deaths annually. Therefore, a lifestyle modification that could improve the survival rate would be of great value.
Recently, researchers conducted a study to determine whether there is a link between vitamin D status and ovarian cancer. They looked at data of 670 participants from the Australian Ovarian Cancer Study.
The Australian Ovarian Cancer Study is a case control study that enrolled women between the ages of 18 and 79 years who were newly diagnosed with ovarian, fallopian tube or primary peritoneal cancer. They recruited the participants from major treatment centers and cancer registries in Australia between 2002 and 2005.
The researchers wanted to compare vitamin D levels to the survival rate of the women. Vitamin D levels were measured once: at diagnosis or after completion of primary treatment and before recurrence. Nurses extracted survival data from medical records up until October 2011.
- Here is what the researchers found:
59% of the women died during follow-up, with 95% of the deaths caused by ovarian cancer.
- Higher vitamin D levels were significantly associated with longer survival.
- Women with vitamin D levels less than 10 ng/ml died at 1.53 times the rate of the women with vitamin D levels between 20 ng/ml and 29.9 ng/ml.
- After adjusting for confounding factors, there was a 7% reduction in risk of dying per 4.0 ng/ml increment in vitamin D levels.
- Further adjustment for stage of disease at diagnosis or amount of residual disease after surgery did not alter the results.
The researchers summarized their findings,
“In conclusion, our data show that serum 25(OH)D concentrations at diagnosis were independently associated with survival after a diagnosis of ovarian cancer (adjusted HR: 0.93, 95% CI: 0.88, 0.99 per 10 nmol/L), suggesting that measurement of serum 25(OH)D at diagnosis may provide additional prognostic information for women newly diagnosed with invasive ovarian cancer.”
There are a couple of important limitations to acknowledge. First, the vitamin D levels were only measured once during the study. This means that the vitamin D status could have changed throughout the study duration, skewing the results. Also, the observational design does not allow causation to be proven.
The researchers pointed out a few of the study’s strengths. The study consisted of a large population sample, which increases the generalizability of the findings. Additionally, the study had a long follow up.
The researchers call for randomized controlled trials to evaluate whether vitamin D supplementation improves the survival rate of women with ovarian cancer.