Study: Colorectal Cancer Also Develops From "Innocent" Polyps

While strategies for detecting colorectal cancer depend largely on discovery of precancerous lesions called adenomas, Canadian researchers report it also develops in a significant number of cases from lesions common in the colon and rectum called hyperplastic polyps.

These polyps have until recently been generally considered "innocent" polyps, according to Dr. Jeremy Jass, a pathologist at McGill University, whose team reviewed 150 different scientific studies over several years.

But researchers now believe that hyperplastic polyps form an "alternative pathway" for the development of colorectal cancer, Jass reported in the journal Gastroenterology.

"Bowel cancer is really a collection of different kinds of cancer," said Jass.

While researchers have long believed that cancerous polyps form in the colon after a gene signals cells to grow, Jass said cancerous polyps are also caused when a cell ignores the signal to die due to a chemical change to DNA called methylation.

"Only in the last few years has it been realized that methylation is an important approach to silence genes," said Jass.

"If colorectal cancer is a heterogeneous disease comprising discrete subsets that evolve through different pathways, it is evident that these subsets will need to be studied individually in the future," he concluded.

Other Sources: Gastroenterology