Selenium shows no benefit in prevention of lung cancer

Jun 05, 2010

Selenium, a supplement taken daily by millions in hopes of protection against cancer and a host of other diseases, has proven to be of no benefit in reducing a patient's risk of developing lung cancer - either a recurrence or second primary malignancy, according to results of an international Phase III clinical trial.

Results from the decade-long study, initiated by the Eastern Cooperative Oncology Group, were presented today at the American Society of Clinical Oncology 2010 Annual Meeting by Daniel D. Karp, M.D., professor in the Department of Thoracic/Head and Neck at The University of Texas MD Anderson Cancer Center.

"Several epidemiological and animal studies have long-suggested a link between deficiency of selenium and ," said Karp, the study's principal investigator. "Interest and research escalated in the late 1990's after a and selenium study, published in 1996, found no benefit against the skin cancer, but did suggest an approximate 30 percent reduction of prostate and lung cancers. Our lung cancer research and another major study for the prevention of prostate cancer evolved from that finding."

These large, follow-up clinical studies investigating the naturally occurring mineral, however, have since proven disappointing. In 2009, the National Cancer Institute (NCI) halted SELECT, an international study of more than 35,000 men investigating if either selenium or Vitamin E, alone or in combination, could reduce the risk of . Both supplements failed to show benefit.

According to the American Cancer Society, approximately 219,440 people were diagnosed with lung cancer in 2009 and 159,390 died from the disease, making it the leading cause of cancer death in both men and women. When caught as early as Stage I, and the tumor is surgically resectable, however, and can even be cured in about 80 percent of the cases. In this population, a chemoprevention agent would be desirable, as the risk of recurrence in Stage I patients after surgery accumulates by one to two percent annually. For example, a patient's risk of developing a new cancer at 10 years is approximately 10-20 percent, said Karp.

From 2000 to 2009, the international NCI-sponsored Phase III study, enrolled 1,522 Stage I non-small cell lung cancer patients, all of whom had their tumors surgically removed and were cancer-free for at least six months post-surgery. Participants were randomized to receive either 200 micrograms of selenium or placebo. The study's primary endpoints were reduction of development of a new cancer, or second primary, and/or recurrence of their initial cancer.

The study was halted early after an interim analysis revealed that the progression-free survival was superior in the placebo arm: 78 percent taking the placebo were alive without recurrence after five years, compared to 72 percent on selenium. A total of 216 secondary primary tumors developed, of which 84 (38.9 percent) were lung cancers. Of those taking selenium, 1.9 percent developed a second primary tumor after the first year, compared to 1.4 percent taking placebo. In total, 3.66 percent of participants in the selenium arm developed a secondary primary tumor of any type after one year, compared to 4.1 percent in the placebo group.

Side effects were minimal and no different in both groups: of those taking placebo, 38 percent had grade 1 or 2 toxicity, and 3 percent had grade 3, compared to 39 percent and 1 percent, respectively in those taking the supplement. The study was stopped by the independent Data and Safety Monitoring Committee due to futility.

The researchers did find that in a small group of the lung cancer patients who were never smoked, selenium did provide a small benefit; however, the size of the group of patients, 94, was too small to be statistically significant.

"Our results demonstrate that is not an effective chemoprevention agent in an unselected group of lung cancer patients, and it's not something we can recommend to our patients to prevent a second cancer from developing or recurring," said Karp. "These findings also remind us that never smokers may represent a unique disease and should be an area for special consideration for research focus.

"Given our results and that of SELECT, physicians now can point to two large NCI-sponsored Phase III trials and tell patients that, at this time, the only definitive studies that have been conducted have been negative," said Karp.

Explore further: AstraZeneca cancer drug, companion test approved

add to favorites email to friend print save as pdf

Related Stories

Selenium may prevent high risk-bladder cancer

Dec 08, 2008

A study published in the December issue of Cancer Prevention Research, a journal of the American Association for Cancer Research, suggests that selenium, a trace mineral found in grains, nuts and meats, may aid in the pr ...

Selenium Supplements May Increase the Risk of Type 2 Diabetes

Jul 13, 2007

Selenium, an antioxidant included in multivitamin tablets thought to have a possible protective effect against the development of type 2 diabetes, may actually increase the risk of developing the disease, an analysis by researchers ...

Recommended for you

Putting the brakes on cancer

Dec 19, 2014

A study led by the University of Dundee, in collaboration with researchers at our University, has uncovered an important role played by a tumour suppressor gene, helping scientists to better understand how ...

Peanut component linked to cancer spread

Dec 19, 2014

Scientists at the University of Liverpool have found that a component of peanuts could encourage the spread and survival of cancer cells in the body.

User comments : 0

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.