Health studies about vitamin D and breast cancer:
Prediagnostic 25-Hydroxyvitamin D Concentrations in Relation to Tumor Molecular Alterations and Risk of Breast Cancer Recurrence (2020)
Conclusion: This study of breast cancer patients found that among those with estrogen-receptor positive breast cancer, those with higher vitamin D levels suffered lower recurrence. Researchers concluded that for every 5ng/ml increase in blood level vitamin D, estrogen-receptor positive breast cancer patients enjoy a 13% reduced risk of breast cancer recurrence and vitamin D measurably downregulates genes sets associated with tumor proliferation.
Abstract C046: Dietary Calcium and Vitamin D and Sun Exposure with the Risk of Breast Cancer Among African American Women (2020)
Conclusion: Due to the vitamin D synthesis-blocking effects of skin melanin, dark-skinned people tend to suffer both higher rates of vitamin D deficiency and vitamin D deficiency diseases, including cancer. This study evaluated and compared the dietary and supplementary intake of vitamin D and sun exposure habits of 1033 black women with breast cancer and 391 healthy black women without breast cancer – all in New Jersey. Researchers found that the women who took vitamin D supplements enjoyed a “significant decreased overall” breast cancer risk. Researchers also found that “more daylight hours spent outdoors in a year predicted a lower risk of pre- and postmenopausal BrCa [breast cancer]”
Low Plasmatic 25-hydroxyvitamin D at Diagnosis is Associated with Axillary Invasion, Chemoresistance and Metastasis in Women with Breast Cancer (2020)
Conclusion: 147 Brazilian women with infiltrative ductal carcinoma (breast cancer in the milk duct) were evaluated for vitamin D status. Blood testing revealed that the patients had low vitamin D levels and that low vitamin D levels significantly correlated with poor prognosis.
Impact of Serum Vitamin D on the Response and the Prognosis in Breast Cancer Patients Treated with Neoadjuvant Chemotherapy (2019)
Conclusion: The vitamin D levels of 236 Japanese breast cancer patients (stages 1 – 3) were evaluated. The study found that pre-menopausal women with higher vitamin D levels enjoyed higher pathological complete response rates following chemotherapy (meaning no detectable trace of cancer following treatment) and women with higher vitamin D levels enjoyed higher rates of relapse-free survival. The study also found that the median vitamin D level among the patients was a terrible 10 ng/ml and only a mere 3% had levels above 20 ng/ml, which is still very low. So 95+% of these breast cancer patients were vitamin D-deficient.
Role of Vitamin D Deficiency and Lack of Sun Exposure in the Incidence of Premenopausal Breast Cancer: A Case Control Study in Sabzevar, Iran (2014)
Conclusion: Sun exposure habits and vitamin D levels were evaluated and compared in 60 premenopausal breast cancer patients and 116 matched, healthy controls in northern Iran. Researchers found that 95% of women in both groups were vitamin D-deficient, but women who reported ever consuming any vitamin D supplements were less likely to develop breast cancer. 98% of the women reported receiving ZERO sun exposure due to how Iranian women dress, which has them completely covered up all the time. Iranian women are also known to start developing breast cancer a decade earlier compared to women in other countries. Could their sun-starved way of dressing be killing them?
Note: This is a technical overview of a study demonstrating how vitamin D prevents and can help treat breast cancer.
Is Prevention of Cancer by Sun Exposure More Than Just the Effect of Vitamin D? A Systematic Review of Epidemiological Studies (2013)
Conclusion: “We found that almost all epidemiological studies suggest that chronic (not intermittent) sun exposure is associated with a reduced risk of colorectal-, breast-, prostate cancer and NHL.”
Conclusion: 120 women being treated for invasive breast cancer and 120 cancer-free women serving as controls had their vitamin D levels tested and compared. The breast cancer group had significantly lower vitamin D levels than the cancer-free group.
Vitamin D and the Mammary Gland: A Review on its Role in Normal Development and Breast Cancer (2012)
Note: Great article summarizing all evidence of vitamin D’s protective role against breast cancer
Conclusion: This meta-analysis reviewed 11 different studies investigating vitamin D status and breast cancer risk and concluded that women with vitamin D levels in the optimal range (above 47 ng /ml) enjoy a 50% lower risk of breast cancer compared to those with only 10 ng/ml or less. They also concluded that breast cancer risk drops approximately 10% for every 10 ng/ml vitamin D blood level increase.
Conclusion: In an experiment involving 224 women with breast cancer, those given 50,000 IU of vitamin per week experienced much more improved vitamin D levels compared to women given only 1,000 IU daily.
Pretreatment Serum Concentration of 25-Hydroxyvitamin D and Breast Cancer Prognostic Characteristics: A Case-Control and a Case-Series Study (2011)
Conclusion: Vitamin D levels were measured and compared for 579 breast cancer patients and 574 healthy age-matched controls. Researchers found that the breast cancer patients had lower vitamin D levels. They also found that for every 10 ng/ml increase in vitamin D blood levels the women enjoyed a 64% lower risk for developing triple-negative breast cancer.
Conclusion: 2,921,714 breast cancer cases from 64 different global regions were analyzed. There is a consistent, world-wide increase in breast cancer diagnoses in the spring and fall. This increase is even stronger in regions farther away from the equator. Fall is when most people’s vitamin D levels begin dropping as the solar radiation starts to get weaker going into winter. Spring is when most people’s vitamin D levels are at their lowest, as they are coming out of winter and this is when it’s most difficult, or completely impossible, for many people to produce their own vitamin D from sun exposure.
Serum 25(OH) Vitamin D and Risk of Breast Cancer: A Nested Case-Control Study from the French E3N Cohort (2010)
Conclusion: The vitamin D levels of 636 breast cancer patients and 1,272 healthy matched controls were evaluated and compared. Researchers found a significant association between vitamin D status and breast cancer risk. Women with the highest vitamin D level group in this study enjoyed a 27% lower risk of breast cancer. (Note: it’s important to note that even among those women, their levels were still actually on the low side)
Reduced Prediagnostic 25-Hydroxyvitamin D Levels in Women with Breast Cancer: A Nested Case-Control Study (2009)
Conclusion: Scientists evaluated the pre-diagnosis vitamin D levels of 142 breast cancer patients and 420 closely-matched healthy controls. What they found was that the breast cancer patients had lower vitamin D levels. Those with the highest pre-diagnosis vitamin D level group enjoyed a 48% lower risk of breast cancer.
Plasma 25-Hydroxyvitamin D and Premenopausal Breast Cancer Risk in a German Case Control Study (2009)
Conclusion: Focusing specifically on premenopausal breast cancer, this study measured and compared the vitamin D levels of 289 premenopausal breast cancer patients and 595 age-matched healthy controls. Researchers found that the women with the lowest vitamin D levels had a much higher risk of breast cancer.
Conclusion: The vitamin D levels of 1,026 breast cancer patients and 1,075 healthy matched controls were evaluated and compared. What researchers found was that among post-menopausal women, those with the lowest vitamin D levels were found to have a significantly higher risk of breast cancer.
Serum 25-Hydroxyvitamin D and Risk of Post-Menopausal Breast Cancer – Results of a Large Case-Control Study (2008)
Conclusion: The vitamin D levels of 1,394 breast cancer patients and 1,365 healthy matched controls were evaluated and compared. What researchers found was that among post-menopausal women, those with the lowest vitamin D levels were found to have a significantly higher risk of breast cancer.
Conclusion: Increasing sun exposure reduces breast cancer risk.
Conclusion: Individuals who achieve adequate vitamin D levels through supplementation and moderate sun exposure are 50% less likely to develop breast cancer compared to individuals who test as being deficient in vitamin D.
Vitamin D From Dietary Intake and Sunlight Exposure and the Risk of Hormone-Receptor-Defined Breast Cancer (2007)
Conclusion: Canada study where researchers compared vitamin D intake and lifetime sun exposure habits between 759 breast cancer patients and 1,135 healthy, matched controls. The study found that women with a higher vitamin D intake and increased lifetime sun exposure enjoy a significantly lower risk of estrogen-receptor positive and progesterone-receptor positive breast cancers, and a slightly lower risk for estrogen and progesterone negative breast cancers. For sun exposure specifically, they found that increased frequency of outdoor activities and ever having an outdoor job between the ages of 10 and 29 was associated with lower breast cancer risk, suggesting that breast cancer could possibly be due to developmental defects caused by early life vitamin D deficiency. The study also found that women who reported exposing more naked skin to the sun enjoyed a lower breast cancer risk. Early life sunburns, while not good for skin cancer risk, are actually associated with lower breast cancer risk.
Conclusion: Sun exposure and vitamin D prevent colon, breast, prostate, and ovarian cancer
Conclusion: Women with higher vitamin D levels have a lower risk of developing breast cancer
Phytoestrogens and Vitamin D Metabolism: A New Concept for the Prevention and Therapy of Colorectal, Prostate, and Mammary Carcinomas. (2004)
Conclusion: Optimization of vitamin D levels is important for tumor prevention
Conclusion: 115,096 cases of breast, colon, and prostate cancer diagnosed over a 28-year period were observed. Researchers found that patients diagnosed in the summer and fall, when population vitamin D levels are highest, had the lowest cancer fatality rate. “The results suggest that a high level of vitamin D3 at the time of diagnosis, and thus, during cancer treatment, may improve prognosis of the three cancer types studied.” The study also found that men and women who received medium to high levels of occupational sun exposure had an extraordinarily lower cancer fatality rate compared to people with low occupational sun exposure.
Sunlight and Mortality From Breast, Ovarian, Colon, Prostate, and Non-Melanoma Skin Cancer: A Composite Death Certificate Based Case-Control Study (2002)
Conclusion: Sun exposure lowers your risk of developing breast, ovarian, prostate, and colon cancer
An Estimate of Premature Cancer Mortality in the U.S. Due to Inadequate Doses of Solar Ultraviolet-B Radiation (2002)
Conclusion: Lack of midday sun exposure increases one’s risk for developing and dying from breast, colon, ovary, prostate, bladder, esophageal, kidney, lung, pancreatic, rectal, stomach, and uterine cancer.
Conclusion: “Sunlight exposure and dietary vitamin D reduce the risk of breast cancer.”
Geographic Variation in Breast Cancer Mortality in the United States: A Hypothesis Involving Exposure to Solar Radiation (1990)
Conclusion: The U.S. breast cancer mortality rate is lower in the South and Southwest regions of America (which are closer to the equator and get more UVB) than it is in the Northeast (farther away from the equator, less UVB)
Conclusion: “ The pattern of increased breast cancer incidence in regions of low solar radiation in the USSR is consistent with the geographical pattern seen for breast cancer mortality in the US and worldwide.”