Selenium and colorectal cancer: The Bonelli study

bonelli study
The Bonelli study showed that a selenium-based antioxidant supplement combination reduces the risk of developing new adenomatous polyps in the large intestine following the removal of colorectal polyps. Adenomas, if not prevented or removed, can develop into colorectal cancer tumors.

Dr. Luigina Bonelli and a team of researchers in Genoa, Italy, were motivated by the following set of compelling facts:

  • Colorectal cancer was the second leading cause of cancer death in Europe.
  • Adenomas in the colon (adenomas are benign tumors, which sometimes transform to malignant tumors) were known to be precursors of colorectal cancer.
  • Patients who had undergone a colonic polypectomy (removal of an adenomatous polyp) had an increased risk of developing colorectal cancer and needed to have periodic follow-up colonoscopies.
  •  Increased risk of developing adenomas was equated with increased risk of developing colorectal cancers.
  •  Observational studies indicated that there was an association between the plasma or serum concentrations of several antioxidant substances including selenium and the risk of colorectal cancer.
  •  In some intervention studies, supplementation with selenium was associated with reductions in the incidence of colorectal cancer.

The time was right to start a large study of the effectiveness of selenium and other antioxidants in reducing the risk of colorectal cancer.

Selenium to reduce the risk of colorectal cancer
Dr. Bonelli and her colleagues wanted to see if daily supplementation with a combination of antioxidants including selenium could reduce the risk of recurrent adenomas in patients who had had one or more adenomatous polyps removed.  The researchers designed a randomized, double-blind, placebo-controlled clinical trial and, over the period of many years, they enrolled a total of 411 patients who had undergone a polypectomy. read more