A Cause of Cancer Disparities? Vitamin D, Say Pair
A Cause of Cancer Disparities? Vitamin D, Say Pair
June 18, 2012 — Vitamin D deficiency is a possible cause of the unexplained disparities in cancer survival rates between black and white Americans, according to the 2 authors of a review published in the April/May/June issue of Dermato-Endocrinology.
The authors believe that differences in socioeconomic status, cancer stage at the time of diagnosis, and treatment are "primary explanatory factors" for cancer survival disparities.
These factors account for "many" of the racial differences in cancer mortality, say William B. Grant, PhD, director of the Sunlight, Nutrition and Health Research Center in San Francisco, California, and Alan N. Peiris, MD, from the Department of Internal Medicine at Eastern Tennessee State University in Johnson City.
However, "even when analyses of cancer survival data include all known or suspected factors affecting survival, African Americans still tend to have a lower survival rate than White Americans," they write.
What else could be at fault? "Unmodeled factors such as biologic differences" are a possibility, they say.
Specifically, they propose vitamin D. "Discussions of cancer survival disparities generally overlook the role of vitamin D," they write in their review of the literature on associations between vitamin D and cancer and between cancer disparities and race.
Theory and Findings
The theory about vitamin D has "biologic plausibility," Drs. Grant and Peiris note.
The literature indicates that there are disparities for 13 types of cancer (after socioeconomic, stage at diagnosis, and treatment are considered): bladder, breast, colon, endometrial, lung, ovarian, pancreatic, prostate, rectal, testicular, and vaginal cancer; Hodgkin's lymphoma; and melanoma. It has been reported that solar ultraviolet (UV) B doses and/or serum 25(OH)D concentrations are inversely correlated with incidence and/or mortality rates for all 13 of these cancers, write the authors.
The studies reviewed do not report a significant correlation between serum 25(OH)D and survival for bladder, lung, and ovarian cancer.
Still, the 13 cancers associated with levels of vitamin D and/or solar UVB are important because a "large body of literature supports a beneficial effect of vitamin D in reducing the risk of cancer incidence and mortality rates." Furthermore, solar UVB irradiance is the primary source of vitamin D for most Americans, accounting for 80% to 90% of vitamin D, they say. However, black Americans, "with darker skin, are less efficient at producing vitamin D from UVB irradiance." In addition, black Americans are "less likely to have as much vitamin D from oral intake." In short, black Americans are vitamin D deficient, say the authors, citing verifying research.
To Drs. Grant and Peiris, all of this adds up to a possible explanation for race-based cancer disparities. They acknowledge that "the issue of cancer etiology is complex and is clearly multifactorial"; nevertheless, they assert that "it appears very likely that vitamin D is an important and often ignored factor in the biology of cancer."
Black Americans Should Take Vitamin D, Says Author
More research is required to confirm this hypothesis, the authors note. However, they suggest that partially repairing cancer racial disparities can be done very simply. "If [this theory is] substantially correct, programs to increase serum 25(OH)D concentrations among African Americans could reduce the cancer disparities," they write.
In a press statement, Dr. Grant suggested that immediate action might be advisable. "Raising vitamin D concentrations to 40 ng/mL by taking vitamin D3 supplements [1000 to 4000 IU/day] is the easiest thing African Americans can do to reduce the heavy burden of cancer they experience," he said.
Vitamin D deficiency is widespread in black America, said a commentator not involved with the study. "Vitamin D deficiency is at epidemic proportions in the United States, and it is far worse among blacks. This paper provides much needed insight into the important role that vitamin D deficiency plays in helping to explain the significantly higher cancer incidence and mortality rates among African Americans," said Emily Allison-Francis, who is the author of a book on the subject, in the press statement.
Dr. Grant explained that vitamin D supplementation could improve the overall health of black Americans. "In addition to reducing the risk of cancer, vitamin D would also reduce the risk of cardiovascular disease, diabetes mellitus, respiratory infections, and many other chronic and infectious diseases," he said.
Dermatoendocrinol. 2012;4(2). Abstract
June 18, 2012 — Vitamin D deficiency is a possible cause of the unexplained disparities in cancer survival rates between black and white Americans, according to the 2 authors of a review published in the April/May/June issue of Dermato-Endocrinology.
The authors believe that differences in socioeconomic status, cancer stage at the time of diagnosis, and treatment are "primary explanatory factors" for cancer survival disparities.
These factors account for "many" of the racial differences in cancer mortality, say William B. Grant, PhD, director of the Sunlight, Nutrition and Health Research Center in San Francisco, California, and Alan N. Peiris, MD, from the Department of Internal Medicine at Eastern Tennessee State University in Johnson City.
However, "even when analyses of cancer survival data include all known or suspected factors affecting survival, African Americans still tend to have a lower survival rate than White Americans," they write.
What else could be at fault? "Unmodeled factors such as biologic differences" are a possibility, they say.
Specifically, they propose vitamin D. "Discussions of cancer survival disparities generally overlook the role of vitamin D," they write in their review of the literature on associations between vitamin D and cancer and between cancer disparities and race.
Theory and Findings
The theory about vitamin D has "biologic plausibility," Drs. Grant and Peiris note.
The literature indicates that there are disparities for 13 types of cancer (after socioeconomic, stage at diagnosis, and treatment are considered): bladder, breast, colon, endometrial, lung, ovarian, pancreatic, prostate, rectal, testicular, and vaginal cancer; Hodgkin's lymphoma; and melanoma. It has been reported that solar ultraviolet (UV) B doses and/or serum 25(OH)D concentrations are inversely correlated with incidence and/or mortality rates for all 13 of these cancers, write the authors.
The studies reviewed do not report a significant correlation between serum 25(OH)D and survival for bladder, lung, and ovarian cancer.
Still, the 13 cancers associated with levels of vitamin D and/or solar UVB are important because a "large body of literature supports a beneficial effect of vitamin D in reducing the risk of cancer incidence and mortality rates." Furthermore, solar UVB irradiance is the primary source of vitamin D for most Americans, accounting for 80% to 90% of vitamin D, they say. However, black Americans, "with darker skin, are less efficient at producing vitamin D from UVB irradiance." In addition, black Americans are "less likely to have as much vitamin D from oral intake." In short, black Americans are vitamin D deficient, say the authors, citing verifying research.
To Drs. Grant and Peiris, all of this adds up to a possible explanation for race-based cancer disparities. They acknowledge that "the issue of cancer etiology is complex and is clearly multifactorial"; nevertheless, they assert that "it appears very likely that vitamin D is an important and often ignored factor in the biology of cancer."
Black Americans Should Take Vitamin D, Says Author
More research is required to confirm this hypothesis, the authors note. However, they suggest that partially repairing cancer racial disparities can be done very simply. "If [this theory is] substantially correct, programs to increase serum 25(OH)D concentrations among African Americans could reduce the cancer disparities," they write.
In a press statement, Dr. Grant suggested that immediate action might be advisable. "Raising vitamin D concentrations to 40 ng/mL by taking vitamin D3 supplements [1000 to 4000 IU/day] is the easiest thing African Americans can do to reduce the heavy burden of cancer they experience," he said.
Vitamin D deficiency is widespread in black America, said a commentator not involved with the study. "Vitamin D deficiency is at epidemic proportions in the United States, and it is far worse among blacks. This paper provides much needed insight into the important role that vitamin D deficiency plays in helping to explain the significantly higher cancer incidence and mortality rates among African Americans," said Emily Allison-Francis, who is the author of a book on the subject, in the press statement.
Dr. Grant explained that vitamin D supplementation could improve the overall health of black Americans. "In addition to reducing the risk of cancer, vitamin D would also reduce the risk of cardiovascular disease, diabetes mellitus, respiratory infections, and many other chronic and infectious diseases," he said.
Dermatoendocrinol. 2012;4(2). Abstract
