Protective effect of calcium in reducing colon cancer polyps lasts for years

April 18, 2005

Anaheim, Calif. -- Long term use of calcium supplements provides a protective effect that lasts for years against development of potentially precancerous colon polyps, researchers at Dartmouth Medical School say.

Their study, presented at the 96th Annual Meeting of the American Association for Cancer Research, found that patients in the treatment group of a randomized trial of calcium supplements had a 36 percent reduction in polyp formation in the five years after the end of the trial, compared to patients in the placebo group.

Although the researchers believe it is premature to recommend widespread use of calcium supplements for chemoprevention, they say their research is the second major study that shows the value of calcium in protecting people at risk of developing worrisome polyps.

"This provides further evidence of the potential of calcium to be used as a chemopreventive agent against development of colorectal cancer," says the study's lead author, Maria Grau, M.D., a research associate in the Section of Biostatistics and Epidemiology at Dartmouth. Co-author John Baron, M.D., a professor of medicine, will be presenting the results at AACR.

Calcium is the most abundant mineral in the body and is essential for the formation and repair of bone and teeth. It is known to play a role in such activities as nerve transmission, muscle contraction, and blood clotting.

It is also the only dietary substance that has been shown to be chemoprotective against development of colorectal polyps. The trial that proved that association, the Calcium Polyp Prevention Study, randomized 930 patients who had a history of developing precancerous adenoma to either 1200 mg. of elemental calcium supplements daily for four years, or to a placebo medication. Results demonstrated a statistically significant 19 percent overall reduction in polyp formation among participants who used the calcium supplements. The reduction in risk of advanced adenomas - more worrisome polyps with a closer association with cancer, was even larger at 28 percent.

The findings being reported at AACR is a continuation of that study. The Calcium Follow Up Study was designed as an observational phase to track polyp formation in those who participated in the Calcium Polyp Prevention Study, as well as to look at the effect of additional use of calcium supplements among the participants.

The Dartmouth research team obtained information on 822 of the original subjects, including detailed records from follow up colonoscopies performed on 597 participants.

Even while adjusting for the use of calcium supplements after the primary study was over, the researchers learned that patients who had been randomized to daily use of the mineral during the trial had a significant reduction (36 percent) in the development of new adenoma polyps during the first five years post-study. There was even a larger effect for protection against development of non-neoplastic hyperplastic polyps - a 48 percent reduction of risk.

But they also found that the protective effect diminished over time. Over the entire follow-up period, which was as much as 10 years in some patients, the protective effect fell to a non-significant 19 percent in patients who had used the supplements in the study. Patients who used calcium supplements after the randomized trial had ended had a non-significant 15 percent reduced risk of developing polyps.

Calcium's long-term protective effect may be due to suppression of a precarcinogenic process that itself takes years to develop, Baron says, but adds that more study is needed to confirm that notion.
-end-
Founded in 1907, the American Association for Cancer Research is a professional society of more than 24,000 laboratory, translational, and clinical scientists engaged in all areas of cancer research in the United States and in more than 60 other countries. AACR's mission is to accelerate the prevention and cure of cancer through research, education, communication, and advocacy. Its principal activities include the publication of five major peer-reviewed scientific journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Epidemiology, Biomarkers & Prevention. AACR's Annual Meetings attract more than 15,000 participants who share new and significant discoveries in the cancer field. Specialty meetings, held throughout the year, focus on the latest developments in all areas of cancer research.

American Association for Cancer Research

Related Cancer Articles from Brightsurf:

New blood cancer treatment works by selectively interfering with cancer cell signalling
University of Alberta scientists have identified the mechanism of action behind a new type of precision cancer drug for blood cancers that is set for human trials, according to research published in Nature Communications.

UCI researchers uncover cancer cell vulnerabilities; may lead to better cancer therapies
A new University of California, Irvine-led study reveals a protein responsible for genetic changes resulting in a variety of cancers, may also be the key to more effective, targeted cancer therapy.

Breast cancer treatment costs highest among young women with metastic cancer
In a fight for their lives, young women, age 18-44, spend double the amount of older women to survive metastatic breast cancer, according to a large statewide study by the University of North Carolina at Chapel Hill.

Cancer mortality continues steady decline, driven by progress against lung cancer
The cancer death rate declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop in cancer mortality ever reported.

Stress in cervical cancer patients associated with higher risk of cancer-specific mortality
Psychological stress was associated with a higher risk of cancer-specific mortality in women diagnosed with cervical cancer.

Cancer-sniffing dogs 97% accurate in identifying lung cancer, according to study in JAOA
The next step will be to further fractionate the samples based on chemical and physical properties, presenting them back to the dogs until the specific biomarkers for each cancer are identified.

Moffitt Cancer Center researchers identify one way T cell function may fail in cancer
Moffitt Cancer Center researchers have discovered a mechanism by which one type of immune cell, CD8+ T cells, can become dysfunctional, impeding its ability to seek and kill cancer cells.

More cancer survivors, fewer cancer specialists point to challenge in meeting care needs
An aging population, a growing number of cancer survivors, and a projected shortage of cancer care providers will result in a challenge in delivering the care for cancer survivors in the United States if systemic changes are not made.

New cancer vaccine platform a potential tool for efficacious targeted cancer therapy
Researchers at the University of Helsinki have discovered a solution in the form of a cancer vaccine platform for improving the efficacy of oncolytic viruses used in cancer treatment.

American Cancer Society outlines blueprint for cancer control in the 21st century
The American Cancer Society is outlining its vision for cancer control in the decades ahead in a series of articles that forms the basis of a national cancer control plan.

Read More: Cancer News and Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.