Serum vitamin D deficiency and risk of epithelial ovarian cancer in Lagos, Nigeria

Predicted 25-hydroxyvitamin D over the adult lifetime and the risk of ovarian cancer

The evidence from previous studies of serum 25-hydroxyvitamin D (25(OH)D) and ovarian cancer risk is not conclusive. However, the 25(OH)D levels were generally only measured in late adulthood, which may not capture the etiologically relevant exposure periods. We investigated predicted 25(OH)D over the adult lifetime in relation to ovarian cancer risk in a population-based case-control study conducted from 2011 to 2016 in Montreal, Canada (n = 490 cases and 896 controls). Predicted 25(OH)D was computed using previously validated regression models. Unconditional multivariable logistic regression models were used to estimate adjusted odds ratios (aORs) and 95% CIs for average predicted 25(OH)D over the adult lifetime and ovarian cancer risk. In addition, the relative importance of different periods of past 25(OH)D exposure was explored using a weighted cumulative exposure (WCE) model. For each 20-nmol/L increase in average predicted 25(OH)D over the adult lifetime, the aOR (95% CI) was 0.73 (0.55-0.96). In WCE analyses, the inverse association was strongest for exposures 5 to 20 years and 35 to 55 years prior to diagnosis, with aORs (95% CIs) of 0.82 (0.69-0.94) and 0.79 (0.66-1.02), respectively, for each 20-nmol/L increase in predicted 25(OH)D. These results support an inverse association between 25(OH)D levels in adulthood and ovarian cancer risk. This article is part of a Special Collection on Gynecological Cancers.

Vitamin D Intake, Blood 25-Hydroxyvitamin D, and Risk of Ovarian Cancer: A Meta-Analysis of Observational Studies

Background: In vitro research suggests that vitamin D may protect against the risk of ovarian cancer. However, ecological and epidemiologic evidence is still debatable. Materials and Methods: We searched eligible studies via MEDLINE and Web of Science databases, as well as a hand search to examine the association between vitamin D intake or blood 25(OH)D (25-hydroxyvitamin D) and ovarian cancer risk in a meta-analysis. The overall relative risk (RR) was determined using a random-effect model. Results: For ovarian cancer incidence, 15 observational studies were included [5,634 cases for vitamin D intake and 975 cases for blood 25(OH)D]. For overall vitamin D intake (from food and supplements), the pooled RR of ovarian cancer risk for the highest versus lowest groups was 0.92 (95% confidence interval [CI]: 0.74-1.14). For blood 25(OH)D levels, however, people with high blood 25(OH)D levels had 37% lower risk of ovarian cancer than those with low levels (pooled RR = 0.63; 95% CI: 0.42-0.93). By study design, the inverse association was stronger in case-control studies than in prospective studies. The dose-response meta-analysis also supports the inverse association between blood 25(OH)D levels and ovarian cancer risk. When the pooled RRs were restricted to studies that adjusted for body mass index (BMI), they tended to be stronger, but the difference by adjustment for BMI was not significant. Conclusion: Our findings suggest that having a high blood 25(OH)D level is associated with a lower risk of ovarian cancer. More well-designed prospective studies are needed to confirm the link between vitamin D status and ovarian cancer risk.

Sex differences in vitamin D metabolism, serum levels and action

The ubiquity of vitamin D metabolising enzymes and vitamin D receptors in mammalian organisms suggests that vitamin D has pleiotropic effects. There are quite a few studies indicating the anticancer, cardioprotective and antidiabetic effects of vitamin D; however, the best-documented actions of vitamin D are the regulation of Ca-phosphate balance and its effect on immune function.Vitamin D levels in organisms are modulated by many environmental and non-environmental factors. One potential factor that may influence vitamin D levels and effects is the sex of the individuals studied. This review focuses on the scientific evidence indicating different synthesis and metabolism of vitamin D in females and males, mainly from PubMed database sources. The article verifies the sex differences in vitamin D levels reported around the world. Moreover, the different effects of vitamin D on the musculoskeletal, cardiovascular, nervous and immune systems, as well as cancer in males and females, were discussed.Most studies addressing sex differences in vitamin D levels and effects are observational studies with conflicting results. Therefore, carefully designed clinical trials and experiments on animal models should be carried out to determine the role of non-environmental factors that may differentiate vitamin D levels in females and males.

The Effect of Vitamin D and Its Analogs in Ovarian Cancer

Ovarian cancer is one of the deadliest cancers in women, due to its heterogeneity and usually late diagnosis. The current first-line therapies of debulking surgery and intensive chemotherapy cause debilitating side effects. Therefore, there is an unmet medical need to find new and effective therapies with fewer side effects, or adjuvant therapies, which could reduce the necessary doses of chemotherapeutics. Vitamin D is one of the main regulators of serum calcium and phosphorus homeostasis, but it has also anticancer effects. It induces differentiation and apoptosis, reduces proliferation and metastatic potential of cancer cells. However, doses that would be effective against cancer cause hypercalcemia. For this reason, synthetic and less calcemic analogs have been developed and tested in terms of their anticancer effect. The anticancer role of vitamin D is best understood in colorectal, breast, and prostate cancer and much less research has been done in ovarian cancer. In this review, we thus summarize the studies on the role of vitamin D and its analogs in vitro and in vivo in ovarian cancer models.