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Vitamin D and Prostate Cancer
Prostate cancer kills 31,000 American men every year, the second leading cause of cancer deaths among men. This year, more than 220,000 American men will be diagnosed with the disease, making prostate cancer the leading cancer among men. Early diagnosis is important as surgery can be curative. After the cancer has spread, especially to bone, treatment options are more limited. Castration, usually chemical, will delay the cancer from spreading for several years, but then the treatment options are quite limited.
No matter what cancer you have, or are trying to prevent, the real question is should cancer patients be left vitamin D deficient? Many experts will tell you that vitamin D should not be taken for prostate cancer until well controlled scientific studies prove it helps. The problem with that approach is two-fold. First, you may die waiting for the studies to be conducted and two, it misses the point. The point is this: men with prostate cancer should not allow themselves to be vitamin D deficient and neither should their doctors.
If you have prostate cancer, please remember that vitamin D is not a cure-all and should never be used as the main treatment for your cancer. Your oncologist will prescribe treatment that has proven efficacy and you should carefully follow his/her advice as the mainstay of treatment. At the same time, you should know that evidence suggests that the proper amount of vitamin D may help you in your fight against prostate cancer.
Next, let's look at selected studies from the scientific literature to see what clues exist about the role vitamin D may play in preventing, and treating, prostate cancer.
In 1990, Schwartz proposed that Vitamin D deficiency may underlie the major risks for prostate cancer, including age, Black race, and northern latitudes. He pointed out that all these factors are associated with decreased synthesis of Vitamin D. Mortality rates from prostate cancer in the U.S. are inversely correlated with ultraviolet radiation, the principal source of Vitamin D.
Anticancer Res. 1990 Sep-Oct;10(5A):1307-11.
In 1992, Hanchette and Schwartz again proposed that sunlight and vitamin D may play a role in prostate cancer. They pointed out that men in the United States were ten times more likely to develop prostate cancer than men in Japan, where men consume higher amounts of vitamin D due to their consumption of fatty fish. Although the authors did not mention it, Japanese men also consume soy, which inhibits the breakdown of calcitriol (activated vitamin D) in the tissues. Furthermore, traditional Japanese men consume higher quantities of omega-3 fatty acids their American counterparts and such fats are now known to dissociate vitamin D metabolites from their binding protein, thus raising the free, or active, levels of those metabolites in the blood.
To support their hypothesis, Hanchette and Schwartz analyzed American prostate cancer deaths in relation to sunlight and discovered a .0001 negative correlation, a very significant association. That is, they found that men who received more sunlight were less likely to die from prostate cancer.
Cancer. 1992 Dec 15;70(12):2861-9.
In the same year, Schwartz discovered that death rates from prostate cancer were correlated with death rates from multiple sclerosis, another disease know to be associated with lack of sunlight. Again, he proposed that lack of vitamin D may a causative factor in both diseases.
Neuroepidemiology. 1992;11(4-6):244-54.
In 1993, Skowronski and colleagues discovered that all three of the prostate cancer cell lines they studied possessed a vitamin D receptor and the active form of vitamin D, calcitriol, "dramatically inhibited" the growth of two of the three cell lines.
Endocrinology. 1993 May;132(5):1952-60.
Over the next several years, four studies appeared to disprove the vitamin D hypothesis. In each case, various metabolites of vitamin D were drawn on large numbers of men who were then followed over many years to see which men developed prostate cancer. Although some of the studies found that activated vitamin D (calcitriol) levels in the blood protected against colon cancer, none of the studies showed that low calcidiol levels (25 hydroxy-vitamin D) were associated with risk of developing prostate cancer. Schwartz's hypothesis appeared to be disproved.
Cancer Epidemiol Biomarkers Prev. 1993 Sep-Oct;2(5):467-72.
Cancer Causes Control. 1995 May;6(3):235-9.
Cancer Epidemiol Biomarkers Prev. 1996 Feb;5(2):121-6.
Cancer Causes Control. 1998 Aug;9(4):425-32.
However, in 1995 Miller and colleagues expanded their earlier work and examined seven prostate cancer cell lines. They found all seven lines had receptors for vitamin D. They also showed that activated vitamin D (calcitriol) inhibited the growth of four of seven prostatic carcinoma cell lines and found that the more vitamin D receptors, the greater the inhibition. Furthermore, they found that the enzyme that breaks down calcitriol in the tissues (24-hydoxylase) reduced that inhibition. That is, the more 24-hydroxylase, the less the cancer cells were inhibited by activated vitamin D. Not only did this mean that activated vitamin D may retard prostate cancer growth, it suggested that substances which interfere with 24 hydroxylase may also prove useful in treating prostate cancer.
Clin Cancer Res. 1995 Sep;1(9):997-1003.
Later in 1995, Feldman and colleagues at Stanford University confirmed Miller's findings and stated, "Based on these findings, we postulate that vitamin D may have protective actions on the development and/or progression of prostate cancer. . . We further hypothesize that vitamin D supplementation may have beneficial effects on retarding the development and/or progression of prostate cancer." For the first time, cancer researchers at a major university seemed to be saying that evidence existed that cholecalciferol (plain vitamin D) may be useful in preventing and treating prostate cancer.
Adv Exp Med Biol. 1995;375:53-63.
In 1998, Gross and colleagues at Stanford conducted the first clinical trial of a vitamin D metabolite in treating advanced prostate cancer. However, instead of raising the tissue levels of activated vitamin D (calcitriol) by supplementing with oral vitamin D (cholecalciferol), they chose to give calcitriol itself. In spite of circumventing the natural system to raise prostate calcitriol levels, they found calcitriol decreased the rate of progression of PSA blood levels (a test of prostate cancer's progression) in 6 of the 7 patients. Elevations in blood calcium levels (hypercalcemia) seriously limited the use of calcitriol and the cancer eventually progressed. (No one knows what would have happened to those seven men if they had been given equipotent doses of vitamin D (cholecalciferol). Cholecalciferol has to be given in massive doses (40,000 units) over an extended period of time (months) to cause significant hypercalcemia. In addition, the tissue production of calcitriol is not rate limited, suggesting that oral cholecalciferol is effective in raising tissue levels of calcitriol).
J Urol. 1998 Jun;159(6):2035-9
In 1998, Schwartz, the same scientist who had first postulated that vitamin D deficiency played a role in prostate cancer, confirmed that prostate cells, including most prostate cancer cell lines, were able to activate vitamin D. Schwartz and his colleagues concluded that "these data suggest a potential role for 25-OH-D (calcidiol) in the chemoprevention of invasive prostate cancer." As the easiest way to raise calcidiol is through oral supplementation with vitamin D, this meant scientists at another major American medical school were suggesting that plain, cheap, non-prescription vitamin D may help prostate cancer.
Cancer Epidemiol Biomarkers Prev. 1998 May;7(5):391-5.
In the year 2000, Ahonen and colleagues conducted a careful study of calcidiol levels in young men and followed them for the development of prostate cancer. Unlike earlier studies, he found a relationship between low vitamin D blood levels and prostate cancer. Ahonen found young men with calcidiol levels below 40 nm/L (16 ng/ml) were three times more likely to develop prostate cancer than were men with higher levels.
Just as important, he found these men were six times more likely to develop invasive cancers. This finding implied a treatment effect for vitamin D as the prevention of invasiveness is a key goal of treatment.
Cancer Causes Control. 2000 Oct;11(9):847-52.
Later in 2000, Barreto and colleagues at Wake Forest University School of Medicine were the first see if calcidiol inhibited prostate cell growth. They found that calcidiol was just as effective as calcitriol in inhibiting growth. The concluded that their findings "support the use of 25 (OH)D (calcidiol) as a chemotherapeutic agent in the treatment of prostate cancer." As oral cholecalciferol is the best way to raise calcidiol levels, it became clear that another group of cancer researchers at a major university medical center was calling for the use of vitamin D in prostate cancer.
Cancer Epidemiol Biomarkers Prev. 2000 Mar;9(3):265-70.
Chen and colleagues at Boston University School of Medicine then demonstrated that calcidiol was just as effective as calcitriol in inhibiting growth of prostate cancer cell lines in the test tube. They also found that a vitamin D analogue already on the market, one known to cause less hypercalcemia that other analogues, was also effective in inhibiting cancer growth. (Vitamin D analogues are patentable modification of calcitriol.) However, their findings about calcidiol again emphasized that readily available vitamin D should help fight prostate cancer. In fact, the authors concluded calcidiol might be a good candidate for "human trials in prostate cancer." Now four different groups of scientist, from four major university medical centers, were calling for the use of vitamin D in prostate cancer.
Clin Cancer Res. 2000 Mar;6(3):901-8.
In 2001, Luscombe and colleagues at the School of Medicine in North Straffordshire Hospital in England published three studies linking ultraviolet exposure and skin type to the development of prostate cancer. They found that cumulative outdoor exposure, outdoor occupations and skin type was associated with reduced risk of advanced stage tumors. They also found that childhood sunburns dramatically reduced the risk of developing prostate cancer, probably because those with fair skin are more likely to burn but also find it easier to make vitamin D in their skin. Furthermore, the found that people who have difficulty making a skin pigment called melanin (a natural sun screen) are much less likely to develop prostate cancer.
Br J Cancer. 2001 Nov 16;85(10):1504-9.
Carcinogenesis. 2001 Sep;22(9):1343-7.
Lancet. 2001 Aug 25;358(9282):641-2.
In addition, in 2001, Zhao and Feldman at Stanford University studied the one prostate cancer cell line (DU 145) that does not respond to calcitriol. They found this cell line, which is poorly differentiated and derived from brain metastasis, can be made to respond to calcitriol by adding drugs which inhibit the breakdown of calcitriol. This raised the possibility that prostate cancers which did not respond to vitamin D could be made responsive by the addition of a metabolic inhibitor. Farhan and colleagues at the University of Vienna Medical School soon showed that the isoflavonoid, genistein, (which is found in soybeans) is a powerful metabolic inhibitor of the enzyme that breaks down calcitriol.
Steroids. 2001 Mar-May;66(3-5):293-300.
J Chromatogr B Analyt Technol Biomed Life Sci. 2002 Sep 25;777(1-2):261-8.
In 2003, Chen and Holick at Boston University School of Medicine reiterated their call for the use of vitamin D in prostate cancer. After reviewing most of the research on the subject, the authors concluded, "adequate exposure to sunlight or oral supplementation might provide a simple way to increase synthesis of calcitriol in the prostate and, therefore, decrease the risk of prostate cancer." They added, "adequate vitamin D nutrition should be maintained, not only for bone health in men and women, but because it might decrease the risk of prostate cancer and mitigate metastatic disease should it develop."
Trends Endocrinol Metab. 2003 Nov;14(9):423-30.
In 2003, Bodiwala and colleagues in England studied sun exposure and skin type and again found that men who sunbathed or otherwise exposed themselves to sunlight were less likely to develop prostate cancer. They also identified men with various combinations of skin type and reduced sun exposure, which were up to 13 times more likely to develop prostate cancer.
Cancer Lett. 2003 Oct 28;200(2):141-8.
Carcinogenesis. 2003 Apr;24(4):711-7.
Cancer Lett. 2003 Mar 31;192(2):145-9.
Also in 2003, Beer and colleagues at the Oregon Health and Science University again tested calcitriol as a treatment for prostate cancer. They found a significant reduction in the rate of increase in PSA, a marker of the cancer's growth although no patient achieved the hoped for 50% reduction. Unfortunately, none of the patients received oral vitamin D supplementation, which would more effectively raise prostate calcitriol levels. In fact, none of the patients were even tested or treated for vitamin D deficiency.
Cancer. 2003 Mar 1;97(5):1217-24.
In 2003, two studies from at the University of Vienna Medical School confirmed that the isoflavonoids in soy dramatically reduce the breakdown of calcitriol in prostate cancer cells. In fact, they found that such products profoundly inhibit the enzyme that metabolizes calcitriol, reducing its activity to almost zero. This again raised the possibility that such compounds could be combined with vitamin D to treat prostate cancer.
Recent Results Cancer Res. 2003;164:413-25.
J Steroid Biochem Mol Biol. 2003 Mar;84(4):423-9.
J Nutr. 2004 May;134(5):1207S-1212S.
Three studies in 2004 examined the association between vitamin D levels and prostate cancer. Two of the studies found no association between vitamin D levels and the subsequent risk of developing prostate cancer. A third study, from Finland, actually raised the possibility that both low and high vitamin D levels are associated with prostate cancer.
Careful analysis of the Finnish paper revealed 57 of the 67 men with high vitamin D blood levels who subsequently developed prostate cancer were from Norway. In Norway, increased consumption of vitamin A (associated with increased risk of prostate cancer) through cod liver oil is common.
In addition, in a letter to the editor, Reinhold Vieth proposed that that the Finnish finding was best explained by annual variations in calcidiol levels causing low tissue calcitriol levels. In their response to Vieth, the authors accepted his explanation as the probable cause for their findings and also proposed that tissue calcidiol levels, not just tissue calcitriol levels, may be protective.
J Steroid Biochem Mol Biol. 2004 May;89-90(1-5):533-7.
Cancer Causes Control. 2004 Apr;15(3):255-65.
Int J Cancer. 2004 Jan 1;108(1):104-8.
Then, researchers in Norway showed that patients diagnosed with prostate cancer in the summer and fall, when vitamin D levels are the highest, have a significantly better prognosis than patients diagnosed in the winter or spring. The authors concluded that their "study supports the hypothesis that vitamin D may influence cancer specific mortality in a beneficial way. A possible mechanism to explain our results might be a combined action of vitamin D and cancer treatment that amplifies the treatment effect. In confirmed, in addition to traditional cancer treatment, vitamin D would be of particular importance in the primary prevention of deaths from cancer."
Cancer Causes Control. 2004 Mar;15(2):149-58.
Lu and his group from Finland then demonstrated for the first time that calcidiol [25(OH)D] is an active steroid hormone in prostate cells. Up until this time, most scientists believed calcidiol was only a prehormone and had to be metabolized into calcitriol before it could regulate genes. Although much less potent than calcitriol, calcidiol is present in much higher concentrations. It now appeared calcidiol is a steroid hormone as well and active in suppressing cell proliferation in prostate tissue.
FASEB J. 2004 Feb;18(2):332-4. Epub 2003 Dec 04.
Young and his group at Boston University School of Medicine then confirmed that tissue calcitriol concentrations are virtually uncontrolled. That is, the usual mechanisms that regulate blood calcitriol concentrations, calcium and parathormone, do not regulate tissue calcitriol levels in prostate cells. In fact, calcitriol did not exhibit negative feedback, and reduce its own production, until pharmacological amounts of calcitriol were introduced. The authors also pointed out that soy would further increase tissue levels and concluded their finding should "encourage the further development of nutritionally-based models for prostate cancer chemoprevention using vitamin D."
Carcinogenesis. 2004 Jun;25(6):967-71. Epub 2004 Jan 16.
In late 2004, Woo, Vieth and colleagues from the University of Toronto presented a groundbreaking paper at the November NIH conference on vitamin D and cancer. They showed that 2,000 units of simple vitamin D (cholecalciferol) either reduced or prevented further increases in PSA in the majority of men with advancing prostate cancer. For the first time, a human interventional trial indicted that simple vitamin D was effective in fighting cancer.
What does this mean? It may mean a lot if you have prostate cancer. Of course, many questions are unanswered. However, many questions are always unanswered, that is the nature of science. It certainly looks as if vitamin D supplementation may help reduce the rate of the growth of prostate cancer.
Only one human study shows that vitamin D helps prostate cancer, but, tragically, no other studies have been done to address that simple question. Hundreds of thousands of people around the world will die this year from prostate cancer and many will be vitamin D deficient.
If asked, most scientists will tell you that vitamin D should not be given to prostate cancer patients until vitamin D is proved to be both safe and effective. However, that is not the question. The question is, should prostate cancer patients be allowed to die from their cancer while not being treated for their vitamin D deficiency. We don't think so, and neither would most victims.
The questions is, what can you do now, based on what is known now. Say you cannot wait for science? The Vitamin D Council will not tell you what to do. We are a non-profit educational organization but we are not your doctors. We will not make any recommendations. In the future, we plan to publish an e-book that will tell you what we would do if we developed prostate cancer.
30 ng/mL) not only is important for maximizing intestinal calcium absorption but also may be important for providing the extrarenal 1
-hydroxylase that is present in most tissues to produce 1,25-dihydroxyvitamin D3. Although chronic excessive exposure to sunlight increases the risk of nonmelanoma skin cancer, the avoidance of all direct sun exposure increases the risk of vitamin D deficiency, which can have serious consequences. Monitoring serum 25-hydroxyvitamin D concentrations yearly should help reveal vitamin D deficiencies. Sensible sun exposure (usually 5–10 min of exposure of the arms and legs or the hands, arms, and face, 2 or 3 times per week) and increased dietary and supplemental vitamin D intakes are reasonable approaches to guarantee vitamin D sufficiency.
± SE) among African Americans and 4.2 ± 0.7% among whites. Among African Americans, hypovitaminosis D was independently associated with consumption of milk or breakfast cereal <3 times/wk, no use of vitamin D supplements, season, urban residence, low body mass index, and no use of oral contraceptives. Even among 243 African Americans who consumed the adequate intake of vitamin D from supplements (200 IU/d), 28.2 ± 2.7% had hypovitaminosis D.
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