Team questions safety, efficacy of selenium and colorectal cancer risk

October 14, 2016, University of Arizona
A UA-led clinical trial found that selenium supplementation did not prevent colon polyps and may increase the risk of type 2 diabetes. Credit: University of Arizona Health Sciences

A 12-year study led by a team of University of Arizona Cancer Center researchers is bringing into question the safety and efficacy of selenium, a popular nutritional supplement touted to combat and reduce the risk of colorectal cancer.

The findings indicate the need for a significant change in practice, given that selenium supplements cannot be recommended for preventing .

Selenium has been a popular nutritional supplement for decades, touted for its antioxidant properties and its role in stopping free radicals from damaging cells and DNA. Studies have shown a deficiency of this micronutrient to be associated with cancer risk.

However, a involving 1,824 participants from clinical centers in Arizona, Colorado, Texas and New York indicates that selenium supplements failed to prevent the development of colon polyps, but significantly increased the risk of developing type 2 diabetes in older individuals.

"The possibility that selenium supplements may increase the risk of type 2 diabetes has been hinted at before," said Peter Lance, MD, deputy director of the UA Cancer Center and the study's principal investigator. "But this is the first study to have substantiated such a risk in the setting of a prospective, randomized, placebo-controlled trial." Study participants were randomized to take 200 mcg of selenium as selenized yeast or a placebo daily.

Cancer — Histopathologic image of colonic carcinoid. Credit: Wikipedia/CC BY-SA 3.0

The trial also looked at celecoxib, a selective COX-2 inhibitor non-steroidal anti-inflammatory drug (NSAID), versus placebo. While the once-daily 400 mg dose prevented in high-risk patients, it increased the risk of hypertension in those with pre-existing cardiovascular risk factors. "Our study has added important refinements to understanding who may benefit most from the colon polyp-preventing effects of celecoxib and how best to avoid cardiovascular toxicity caused by this agent," added Dr. Lance.

Further UA-led studies are under way to define the biological mechanisms underlying the effects, including toxicity, of . A study is planned to target celecoxib to those patients who will benefit most from the colon polyp-preventing actions of celecoxib while minimizing cardiovascular toxicity.

The findings of the Selenium and Celecoxib Trial recently were published online before print in two articles in the Journal of the National Cancer Institute (JNCI): "Selenium Supplementation for Prevention of Colorectal Adenomas and Risk of Associated Type 2 Diabetes" and "Celecoxib for the Prevention of Colorectal Adenomas: Results of a Suspended Randomized Controlled Trial". The articles will appear in print in the December 2016 issue of JNCI.

Explore further: Selenium status influence cancer risk

More information: Patricia A. Thompson et al, Selenium Supplementation for Prevention of Colorectal Adenomas and Risk of Associated Type 2 Diabetes, Journal of the National Cancer Institute (2016). DOI: 10.1093/jnci/djw152

Patricia A. Thompson et al. Celecoxib for the Prevention of Colorectal Adenomas: Results of a Suspended Randomized Controlled Trial, Journal of the National Cancer Institute (2016). DOI: 10.1093/jnci/djw151

Related Stories

Selenium status influence cancer risk

August 31, 2016
As a nutritional trace element, selenium forms an essential part of our diet. In collaboration with the International Agency for Research on Cancer, researchers from Charité - Universitätsmedizin Berlin have been able to ...

Selenium and vitamin E supplementation over recommended dietary intake may raise prostate cancer risk

February 21, 2014
A multi-center study led by Fred Hutchinson Cancer Research Center has found that high-dose supplementation with both the trace element selenium and vitamin E increase the risk of high-grade prostate cancer. But importantly, ...

Vitamin E, selenium supplements unlikely to effect age-related cataracts in men

September 18, 2014
Taking daily supplements of selenium and/or vitamin E appears to have no significant effect on the development of age-related cataracts in men, writes Author William G. Christen, Sc.D., of Brigham & Women's Hospital and Harvard ...

Taking additional selenium will not reduce cancer risk

May 11, 2011
Although some people believe that taking selenium can reduce a person's risk of cancer, a Cochrane Systematic Review of randomised controlled clinical trials found no protective effect against non-melanoma skin cancer or ...

Recommended for you

'Kiss of death' cancer: How computational geeks may have uncovered a therapy for a deadly disease

June 19, 2018
It's called the 'kiss of death'. Triple negative breast cancer has no targeted drug therapy and, as such, the only hope for these patients is chemotherapy. Triple negative breast cancer is aggressive and deadly. Patients ...

Ovarian cancer cells switched off by 'unusual' mechanism

June 19, 2018
Scientists at the Ovarian Cancer Action Research Centre at Imperial College London have discovered a mechanism that deactivates ovarian cancer cells.

Team discovers gene mutations linked to pancreatic cancer

June 19, 2018
Six genes contain mutations that may be passed down in families, substantially increasing a person's risk for pancreatic cancer. That's according to Mayo Clinic research published in the June 19 edition of the JAMA. However, ...

Breast cancer could be prevented by targeting epigenetic proteins, study suggests

June 19, 2018
Researchers at the Princess Margaret Cancer Centre in Toronto have discovered that epigenetic proteins promote the proliferation of mammary gland stem cells in response to the sex hormone progesterone. The study, which will ...

Targeting the engine room of the cancer cell

June 18, 2018
Researchers at Columbia University Irving Medical Center (CUIMC) have developed a highly innovative computational framework that can support personalized cancer treatment by matching individual tumors with the drugs or drug ...

Study suggests well-known growth suppressor actually fuels lethal brain cancers

June 18, 2018
Scientists report finding a potentially promising treatment target for aggressive and deadly high-grade brain cancers like glioblastoma. But they also say the current lack of a drug that hits the molecular target keeps it ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.