Health studies about sunlight and cancer:
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]”
Conclusion: This is a meta-analysis of 13 different studies investigating associations between daily sun exposure (in adolescence, adulthood, and lifetime) and risk of breast cancer. Researchers found that adults who spend 1+ hours in the sun daily during summer have a lower risk of developing breast cancer compared to those who spend less than 1 hour in the sun daily. Regular sun exposure during adolescence was found to also possibly provide a chemoprotective benefit into adulthood, even if sun exposure declines with age. Indirect sunlight (ambient UV) was found to offer no benefits.
Intake of Vitamin D and Calcium, Sun exposure, and Risk of Breast Cancer Subtypes Among Black Women (2019)
Conclusion: To investigate associations between vitamin D, sun exposure, and risk of breast cancer in black women, researchers evaluated 1724 black female breast cancer patients and 1233 healthy matched controls for their reported total amount of daylight hours spent outside (in the sun). What they found is that those who spent the most time outside had the lowest risk of breast cancer, for all types of breast cancer, compared to the women who reported the least time spent outside. It’s also important to mention that blacks, due to the vitamin D production-blocking effects of melanin, tend to suffer much higher rates of vitamin D deficiency and black women are nearly twice as likely to develop the more aggressive types of breast cancer.
Conclusion: Data from the Nurses’ Health Study II was evaluated for associations between sun exposure history and breast cancer incidence. The Nurses’ Health Study II is a giant study following 112,447 registered American nurses since 1989. This study used data from 1989 to 2013. Over the course of this period 3,959 of the nurses would develop breast cancer. Included in this study was self-reporting on the nurses’ sun exposure habits in childhood, at age 15, and age 30, along with the latitudes they lived at. What this study found was a slight association between higher self-reported UV exposure early in life and a lower risk for estrogen receptor-negative breast cancer.
Environmental and Lifestyle Risk Factors of Breast Cancer in Malta—A Retrospective Case-Control Study (2016)
Conclusion: 200 breast cancer patients and 403 matched controls in Malta were evaluated for a variety of lifestyle factors, including sun exposure, and risk of breast cancer. Researchers found that breast cancer rates were lower in those who reported receiving more summer sun exposure. “Though prolonged sunlight exposure damages the skin, it has been found that it reduces the risk of breast cancer—possibly due to vitamin D production and its role in breast cell growth.”
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?
Sun Exposure, Vitamin D Receptor Genetic Variants, and Risk of Breast Cancer in the Agricultural Health Study (2014)
Conclusion: Sun exposure habits and breast cancer rates were evaluated in 31,021 ladies for a decade. Out of this data set, researchers compared 293 breast cancer cases with 586 matched controls and found that women who get 1+ hours of sun exposure daily have a significantly lower risk of breast cancer compared to women who get less sun exposure. “Our results suggest that sun exposure may be associated with reduced risk of breast cancer.”
Association Between Ultraviolet Radiation, Skin Sun Sensitivity and Risk of Pancreatic Cancer (2013)
Conclusion: “Being born in or living in areas of higher ambient UVR [ultraviolet radiation] (compared to lower ambient UVR) was associated with about 30-40% lower risk of pancreatic cancer. People with fair skin colour had 47% lower risk of pancreatic cancer than those with dark skin colour (95% CI 0.37-0.75). There was some suggestion of increased risk with increased average number of hours spent outside at work. This study suggests that people with light skin colour or those born or living in areas of high ambient UVR have lower risk of pancreatic cancer. Our analysis supports an association between UVR and pancreatic cancer, possibly mediated through production of vitamin D.”
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.”
Note: This article covers many studies providing strong evidence that a lack of UVB exposure / vitamin D is strongly associated with colon cancer, rectal cancer, breast cancer, gastric cancer, non-Hodgkin’s lymphoma, Hodgkin’s lymphoma, bladder cancer, ovarian cancer, pancreatic cancer, esophageal cancer, lung cancer, cervical cancer, renal cancer, vulvar cancer, gallbladder cancer, brain cancer, multiple myeloma, leukemia, prostate cancer, laryngeal cancer, thyroid cancer, melanoma, and pharyngeal cancer.
Conclusion: 995 esophageal cancer patients in Australia were analyzed along with 1471 population controls. The cancer patients reported having less sun exposure over their lifetimes and tended to live in less sunny areas than the controls.
Conclusion: 1,500 ovarian cancer patients and 1,459 healthy female controls in Australia were analyzed. The top third of all the women who reported having the most sun exposure over their lifetimes and who lived in the sunnier areas of Australia had the lowest risk for ovarian cancer. Those in the bottom third for lifetime sun exposure had the highest risk for ovarian cancer. “Women who spent their lives in areas with higher levels of ambient UVR [ultraviolet radiation] had a lower risk of developing epithelial ovarian cancer than those living in areas with lower levels of ambient UVR.”
Vitamin D and Cancer (2012)
Conclusion: “In clinical studies, an impact of vitamin D has been reported in different types of cancer. A low vitamin D activity is associated with an increased cancer risk and a more aggressive tumor growth, while high activity of this pathway induces antitumoral effects. In particular, serum circulating levels of 25(OH)D levels <20 ng/ml seems to expose to the risk of developing mammary and colorectal cancer.”
Exposure to Ultraviolet Radiation: Association with Susceptibility and Age at Presentation with Prostate Cancer (2011)
Conclusion: “A positive association between latitude and prostate cancer mortality has been interpreted to indicate that ultraviolet radiation (UVR) protects against development of this cancer.”
Ultraviolet Sunlight Exposure During Adolescence and Adulthood and Breast Cancer Risk: A Population-based Case-Control Study Among Ontario Women (2011)
Conclusion: 3,101 breast cancer patients and 3,471 healthy, age-matched controls in Canada were evaluated for lifetime sun exposure habits and time spent outdoors. Researchers found that women who reported more lifetime sun exposure (21+ hours outside per week versus less than 6 hours per week) enjoyed a lower risk of breast cancer and that even increased sun exposure in adolescence alone carried a protective effect into adulthood, even if sun exposure decreased with age.
Increased UVA Exposures and Decreased Cutaneous Vitamin D3 Levels May Be Responsible for the Increasing Incidence of Melanoma (2009)
Conclusion: Low vitamin D levels resulting from a lack of direct, midday sun exposure increase the risk of developing melanoma skin cancer
Note: Comprehensive overview on the evidence of vitamin D and UVB’s anti-cancer benefits.
Incident Invasive Breast Cancer, Geographic Location of Residence, and Reported Average Time Spent Outside (2009)
Conclusion: The Women’s Health Initiative Observational Study followed 71,662 participants over a decade. Over that period 2,535 women would develop breast cancer. What researchers found was that women who reported spending 2+ hours outside daily had a 20% lower risk of breast cancer compared to women who reported spending less than 30 minutes outside daily. “The observed association between time spent outside and breast cancer risk support the hypothesis that vitamin D may protect against breast cancer”
Conclusion: Although UVB exposure can cause non-melanoma skin cancer, it’s also the same UV spectrum necessary for the epidermal vitamin D synthesis that prevents other cancers.
Sun Exposure Prior to Diagnosis is Associated with Improved Survival in Melanoma Patients: Results from a Long-Term Follow-Up Study of Italian Patients (2008)
Conclusion: Melanoma skin cancer patients who enjoy more sun exposure over their lifetimes also enjoy higher survival rates
Relationship Between Low Ultraviolet B Irradiance and Higher Breast Cancer Risk in 107 Countries (2008)
Conclusion: This study looked at breast cancer rates in 107 different countries and found that countries closer to the equator, getting more UVB sunlight, enjoy significantly lower incidence rates of breast cancer compared to countries father away from the equator.
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
Conclusion: Increasing sun exposure reduces breast cancer risk.
Sun Exposure, Vitamin D Receptor Gene Polymorphisms, and Breast Cancer Risk in a Multiethnic Population (2007)
Conclusion: This study evaluated 1,788 newly diagnosed breast cancer patients and 2,129 healthy controls for lifetime sun exposure. Researchers found that light-skinned women who enjoyed the most sun exposure had a 47% lower risk of advanced breast cancer.
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.
Solar ultraviolet-B exposure and cancer incidence and mortality in the United States, 1993-2002 (2006)
Conclusion: For the period of 1993 to 2002, satellite-measured solar UV-B levels, 3+ million cancer incidences, and 3 million cancer deaths in America were analyzed. There was a correlation between lower UVB levels and an increased rate of “bladder, colon, Hodgkin lymphoma, myeloma, prostate, rectum, stomach, uterus, and vulva” cancer, and to a lesser extent for “breast, kidney, leukemia, non-Hodgkin lymphoma, pancreas, and small intestine” cancer.
Conclusion: “From our review, it becomes clear that there is an increasing evidence of sunlight having a preventive effect on the initiation and/or progression of different kinds of cancer.”
Conclusion: Sun exposure and vitamin D prevent colon, breast, prostate, and ovarian cancer
The Association of Solar Ultraviolet B (UVB) with Reducing Risk of Cancer: Multifactorial Ecologic Analysis of Geographic Variation in Age-Adjusted Cancer Mortality Rates (2006)
Conclusion: A study of American cancer mortality rates from 1950-1969 and 1970-1994 found that cancer mortality rates have been higher in areas of American with weaker UVB solar radiation (i.e. northern latitudes).
Conclusion: Study examined 551 people with non-hodgkin lymphoma and 462 controls and found that those who received more UV exposure through sunlight and tanning lamps had a slightly reduced risk for NHL.
Conclusion: Within the U.S., the states with the highest amount of solar radiation (New Mexico, Arizona, Florida, California, Texas – low latitudes) have the lowest rates of colon cancer mortality and the states with the lowest solar radiation (New York, New Jersey, Rhode Island, Connecticut – high latitudes) have the highest rates of colon cancer mortality. Lower latitude populations tend to have higher vitamin D levels than higher latitude populations.
Conclusion: “Sun exposure is associated with increased survival from melanoma.”
Conclusion: Outdoor workers are at a lower risk of developing melanoma skin cancer compared to indoor workers.
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.
The Influence of Painful Sunburns and Lifetime Sun Exposure on the Risk of Actinic Keratoses, Seborrheic Warts, Melanocytic Nevi, Atypical Nevi, and Skin Cancer (2003)
Conclusion: While chronic lifetime sun exposure is associated with an increased risk for non-melanoma skin cancer, lifetime sun exposure is also associated with a decreased risk for deadly melanoma skin cancer.
Sunlight and Mortality from Breast, Ovarian, Colon, Prostate, and Non-Melanoma Skin Cancer: A Composite Death Certificate Based Case-Control Study (2002)
Conclusion: American cancer deaths and matched non-cancer control deaths in 24 American states were evaluated for lifetime sun exposure by evaluating the subjects based on the solar region they lived their lifetime in (state) and their occupation (how much time their job had them in the sun versus indoors) – all this info was collected from their death certificates. Researchers found that the people who received the most lifetime sun exposure enjoyed significantly lower rates of internal cancers, and these associations were stronger in the states with more intense sunlight. These people also had the highest rates of non-melanoma skin cancer, but that’s a good trade. These associations were the strongest for female breast and colon cancer, but also significant in ovarian and prostate 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, ovarian, prostate, bladder, esophageal, kidney, lung, pancreatic, rectal, stomach, and uterine cancer.
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
Prostate Cancer Risk: Associations With Ultraviolet Radiation, Tyrosinase and Melanocortin-1 Receptor Genotypes (2001)
Conclusion: “Exposure to ultraviolet radiation may reduce prostate cancer risk”
Conclusion: “Sunlight exposure and dietary vitamin D reduce the risk of breast cancer.”
Conclusion: “Sunlight may be a protective factor for ovarian cancer mortality.”
Conclusion: “The research studies presented here suggest that dermal activation of vitamin D from regular, moderate sun exposure has a strong protective effect in the prevention of breast and colon cancer; has a weaker protective effect in melanoma, leukemia, and lymphoma; and acts to lower overall cancer death rates.”
Geographic Patterns of Prostate Cancer Mortality. Evidence for a Protective Effect of Ultraviolet Radiation (1992)
Conclusion: There are lower prostate cancer mortality rates in the southern regions of America compared to the northern regions due to the south receiving stronger sunlight with more vitamin D-producing UVB radiation.
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: Navy personnel who work indoors have an increased incidence of melanoma skin cancer compared to personnel who work outdoors.
Conclusion: Sun exposure increases immunity to cancer