Vitamin D and Prostate Cancer

Prostate cancer

The prostate is a small gland found in men. It is about the size of a walnut and is part of the reproductive system. Prostate cancer occurs when prostate cells grow abnormally and form clumps called tumors. Prostate cancer is very common, especially in older men. It is not yet known what causes prostate cancer, but researchers think it is a combination of genetic, environmental, and hormonal factors. Hormones called androgens play a large role in the development of prostate cancer. Research has shown that there is a link between prostate cancer and vitamin D. Studies have found that men with prostate cancer tend to have lower levels of vitamin D. Men with healthy levels of vitamin D tend to have lower rates of death from prostate cancer and less aggressive cancers. However, more experiments need to be done to determine if vitamin D is an effective treatment for people with prostate cancer. Researchers don’t know yet whether taking a vitamin D supplement or getting more sun exposure can help to prevent, treat, or manage prostate cancer. If you have prostate cancer and want to take vitamin D, it is unlikely to make your prostate cancer worse or cause you any harm, as long as you take less than 10,000 IU per day. However, it’s not proven that taking vitamin D will help to treat or prevent prostate cancer. If you have prostate cancer, you shouldn’t take vitamin D in place of your treatment medications. Talk to your physician for more advice about taking vitamin D supplements.

What is prostate cancer?

The prostate is a small gland found in men. It is about the size of a walnut and is part of the reproductive system. Its function is to produce seminal fluid and transport sperm¹. Prostate cancer develops when some of the cells in your prostate start to grow and become abnormal. Instead of the cells dying off like they should, they grow faster than usual and start to form clumps of cells. These clumps are called tumors¹. Sometimes prostate cancer develops slowly and stays in the prostate, which can be treated by removing the prostate gland. However, other times prostate cancer develops faster and more aggressively and spreads to other parts of the body.

How common is prostate cancer?

Prostate cancer is considered very common². It is the second most common cancer in men, after skin cancer. One in every 6 men is estimated to have prostate cancer. You are more likely to get prostate cancer if:

• You are over the age of 50.
• You are African American.
• You have a father, brother, or son that has had prostate cancer.

African American men are 2.5 times more likely to die from prostate cancer than Caucasian men. Although it can be treatable, prostate cancer is the second leading cause of death from cancer in men in the United States³.

What are the symptoms of prostate cancer?

In early stages of prostate cancer, you may not have any symptoms at all. It is recommended that you get tested for prostate cancer as you age, even if you don’t have any symptoms. To check for prostate cancer, your doctor will⁴:

• Perform a digital rectum scan, where your doctor will stick a finger in your rectum to see if your prostate is enlarged.
• Perform a prostate-specific antigen (PSA) blood test. Low levels of PSA are normally found in your blood. If your PSA level is higher than normal, this can mean that your prostate is infected, inflamed, bigger than usual, or cancerous.

Sometimes, tests will show that while you do have prostate cancer, it’s not aggressive enough to treat and your doctor will choose to just monitor it. This means that your prostate cancer will not go away, but it has not progressed enough to need surgery or radiation therapy. If the results of these tests are abnormal, your doctor will then do more tests to determine if you have prostate cancer and how aggressive it is. Sometimes, tests will show that while you do have prostate cancer, it’s not aggressive enough to treat and your doctor will choose to just monitor it. This means that your prostate cancer will not go away, but it has not progressed enough to need surgery or radiation therapy. Advanced prostate cancer tends to show symptoms, which may include:

• Trouble urinating
• Decreased force in the stream of urine
• Blood in the urine
• Blood in the semen
• Swelling in the legs
• Discomfort in the pelvic area
• Bone pain

If you have any of these symptoms, make an appointment with your doctor. If you don’t have symptoms, ask your doctor about the benefits and risks of getting checked for prostate cancer. Many organizations have different recommendations on whether or not to screen and at what age to start screening for prostate cancer.

What causes prostate cancer?

It is not known exactly what causes prostate cancer. Doctors and scientists know that mutations in DNA can cause prostate cells to become cancerous, but they do not know what causes these mutations. Researchers think that prostate cancer is caused by a combination of genetic, hormonal, and environmental factors⁵. A class of hormones called androgens promote tumor growth in prostate cancer. Testosterone is the most well-known androgen. A common therapy for advanced prostate cancer is called androgen deprivation therapy, or ADT, which lowers the amount of androgens in your body. Prostate cells need androgen to grow and survive, so ADT promotes the death of prostate cancer cells⁶.

What is the link between prostate cancer and vitamin D?

Research has shown that there is a link between prostate cancer and vitamin D. Studies have found that men with prostate cancer tend to have lower levels of vitamin D. However, the relationship between prostate cancer and vitamin D is complex and still being researched. Vitamin D receptors are found on the surface of a cell and vitamin D can attach themselves to these receptors. By binding to a receptor, vitamin D sends chemical signals that direct a cell to do something, such as divide or die. There are vitamin D receptors in prostate tissue, and vitamin D can bind to these receptors. This may cause cancerous cells to die, stop growing, or stop from spreading to other parts of the body. Therefore, it is thought that vitamin D may help in protecting against the progression of prostate cancer. Cells in the prostate are able to take the inactive form of vitamin D and activate it. Some of the cancerous cells in the prostate lose this ability, but they still have receptors for vitamin D, which could mean that supplementing with vitamin D may help to slow the growth of cancerous cells⁶.

What does the research say, in general, about prostate cancer and vitamin D?

Preventing prostate cancer

Doctors and scientists have found that prostate cancer rates in the United States are highest in places that get the least amount of sun exposure. Your body makes vitamin D from sunlight, so it is thought that having low levels of vitamin D may play a role in the development of prostate cancer. A large study that followed men for 13 years found that those with the lowest levels of vitamin D had the highest risk of getting prostate cancer⁵. Men with dark skin are more likely to develop prostate cancer, which may be because they need more sun exposure to make enough vitamin D, which is especially hard in areas with low sunlight⁷. However, most studies on vitamin D and prevention of prostate cancer have been observational, meaning that researchers can’t say for sure whether or not vitamin D can help to prevent prostate cancer.

Prostate cancer outcomes and treatment

Not many studies have been examined the treatment of prostate cancer with only vitamin D, but some studies have been done on men with prostate cancer to see how vitamin D affects different outcomes, like survival, stage of cancer, and whether or not the cancer spreads to other parts of the body. A study done on veterans in the United States found that men with prostate cancer who had the lowest levels of vitamin D were less likely to survive compared to men with higher vitamin D levels⁸. Other studies have found that men with low levels of vitamin D were twice as likely to have their prostate cancer spread to other body parts compared to men with higher vitamin D levels⁹. Another study followed American males for 18 years and found that the men with the lowest vitamin D levels had the most aggressive forms of prostate cancer. Researchers think that vitamin D might help to slow the progression of prostate cancer¹⁰. About half of men with prostate cancer will receive ADT. However, ADT has negative side effects, including bone loss. A study of men undergoing ADT found that those who took vitamin D supplements had higher bone mineral density than those who didn’t take vitamin D. Bone loss and fractures in men with prostate cancer are linked to worse outcomes and survival, so taking vitamin D while on ADT for prostate cancer may help to prolong life¹¹.

What does the recent research say about prostate cancer and vitamin D?

Preventing prostate cancer

A study done in the United States in 2014looked at men who were having their first prostate biopsy. Biopsies remove a small portion of tissue to look at the cells and see if they are cancerous. The researchers wanted to know if there were differences in vitamin D levels between men who had positive and negative biopsies. They found that¹²:

• African-American men with low levels of vitamin D had higher odds of having prostate cancer.
• Caucasian and African-American men with positive biopsies had a higher tumor stage if they had low levels of vitamin D.

Although they didn’t find an important difference in the vitamin D levels between positive and negative biopsies, they did discover that the more aggressive and advanced tumors were linked to lower levels of vitamin D.

Prostate cancer outcomes and treatment

An experiment done in the United States in 2012 looked at men with early stage prostate cancer. The researchers gave all of the men 4,000 IU of vitamin D per day for one year. They looked at the vitamin D levels in the men and found that^13,14:

• Over half of the men showed improvements in their biopsy results after a year.
• The men had fewer positive cores on their biopsy, which means that there were fewer cancerous cells around the tumor.

Many people with early stage prostate cancer will choose to monitor the disease carefully, rather than undergoing treatment with potential side effects. These researchers conclude that taking vitamin D may help to slow the progression of prostate cancer, so that less people have to go through difficult treatment. An American study from 2012 looked at men with prostate cancer and followed them for 5 years. They found out how many men had died during that time and how many of their cancers spread to other body parts. The researchers found that¹⁵:

• Men with the lowest levels of vitamin D had almost double the chance of dying from prostate cancer or having it spread to other body parts, compared to men with the highest levels of vitamin D.

The researchers think that vitamin D may work to help slow prostate cancer progression by increasing the death of cancerous cells. A study from 2009 in Norwayresearched men with prostate cancer, some of who were on hormonal treatment (ADT). They found that¹⁶:

• The risk of dying was lower for men with higher levels of vitamin D.
• There was a strong relationship between levels of vitamin D and death from prostate cancer, especially in men on ADT.

These researchers conclude that vitamin D may improve prostate cancer outcomes in men on ADT by helping the body to lower androgen levels even more.

Key points from the research

• Prostate cancer is more common in regions with lower amounts of sunlight exposure.
• Men with lower levels of vitamin D are more likely to die from prostate cancer or have it spread to other parts of the body.
• Lower vitamin D levels are linked to more aggressive forms of prostate cancer.
• Having good levels of vitamin D may help to slow the progression of prostate cancer.
• More experiments need to be done to determine if taking vitamin D supplements can help to prevent or treat prostate cancer.

What does this mean for me?

Research has shown that there is a link between vitamin D and prostate cancer. Most studies have shown that having higher levels of vitamin D can lead to better outcomes, such as lower mortality rates and are associated with less aggressive cancers. However, more experiments need to be done to determine if vitamin D is an effective treatment for people with prostate cancer. Doctors don’t know yet whether taking a vitamin D supplement, or getting more sun exposure, can help to prevent, treat, or manage prostate cancer. If you have prostate cancer and want to take vitamin D, it is unlikely to make your prostate cancer worse or cause you any harm, as long as you take less than 10,000 IU per day. However, it’s not proven that taking vitamin D will help to treat or prevent prostate cancer. If you have prostate cancer, you shouldn’t take vitamin D in place of your treatment medications. Talk to your physician for more advice about taking supplements.

References

1. Mayo Clinic. Prostate Cancer. 2012. https://www.mayoclinic.org/diseases-conditions/prostate-cancer/symptoms-causes/syc-20353087
2. Prostate Cancer Foundation. Prostate Cancer FAQs. 2013. https://www.pcf.org/patient-resources/family-cancer-risk/prostate-cancer-risk-factors/
3. Krishnan A V, Feldman D, Pike J, Adams J. Vitamin D and Prostate Cancer. Third. Elsevier; 2011.
4. American Cancer Society. What is prostate cancer? 2013. https://www.cancer.org/cancer/types/prostate-cancer/about/what-is-prostate-cancer.html
5. Wang Z, Fan J, Liu M, et al. Nutraceuticals for prostate cancer chemoprevention: from molecular mechanisms to clinical application. Expert Opin. Investig. Drugs 2013;22(12):1613-26. doi:10.1517/13543784.2013.833183.
6. Schwartz GG. Vitamin D and intervention trials in prostate cancer: from theory to therapy. Ann. Epidemiol. 2009;19(2):96-102. doi:10.1016/j.annepidem.2008.03.007.
7. Gilbert R, Metcalfe C, Oliver SE, et al. Life course sun exposure and risk of prostate cancer: population-based nested case-control (ProtecT) and meta-analysis. Inst J Cancer 2010;125(6):1414-1423. doi:10.1002/ijc.24411.Life.
8. Der T, Bailey BA, Youssef D, Manning T, Grant WB, Peiris AN. Vitamin D and Prostate Cancer Survival in Veterans. Mil. Med. 2014;179(January):81-85.
9. Gilbert R, Metcalfe C, Fraser WD, et al. Europe PMC Funders Group Associations of Circulating 25-hydroxyvitamin D with prostate cancer diagnosis , stage and grade. Inst J Cancer 2012;131(5):1187-1196. doi:10.1002/ijc.27327.Associations.
10. Li H, Stampfer MJ, Hollis JBW, et al. A prospective study of plasma vitamin D metabolites, vitamin D receptor polymorphisms, and prostate cancer. PLoS Med. 2007;4(3):e103. doi:10.1371/journal.pmed.0040103.
11. Alibhai SMH, Mohamedali HZ, Gulamhusein H, et al. Changes in bone mineral density in men starting androgen deprivation therapy and the protective role of vitamin D. Osteoporos. Int. 2013;24(10):2571-9. doi:10.1007/s00198-013-2343-4.
12. Murphy AB, Nyame Y, Martin IK, et al. Vitamin D Deficiency Predicts Prostate Biopsy Outcomes. Clin Cancer Res. 2014;20(9):2289-99.
13. Hollis BW, Marshall DT, Savage SJ, Garrett-Mayer E, Kindy MS, Gattoni-Celli S. Vitamin D3 supplementation, low-risk prostate cancer, and health disparities. J. Steroid Biochem. Mol. Biol. 2013;136:233-7. doi:10.1016/j.jsbmb.2012.11.012.
14. Marshall DT, Savage SJ, Garrett-Mayer E, et al. Vitamin D3 supplementation at 4000 International Units per day for one year results in a decrease of positive cores at repeat biopsy in subjects with low-risk prostate cancer under active surveillance. J Clin Endocrinol Metab 2012;9(7):1-10.
15. Shui IM, Mucci L a, Kraft P, et al. Vitamin D-related genetic variation, plasma vitamin D, and risk of lethal prostate cancer: a prospective nested case-control study. J. Natl. Cancer Inst. 2012;104(9):690-9. doi:10.1093/jnci/djs189.
16. Tretli S, Hernes E, Berg JP, Hestvik UE, Robsahm TE. Association between serum 25(OH)D and death from prostate cancer. Br. J. Cancer 2009;100(3):450-4. doi:10.1038/sj.bjc.6604865.