Experts opine that in spite of the reports about its limitations, colonoscopy is still among the best ways to save lives from colorectal cancer. It has also been found that it is better at detecting cancer on the left side of the colon.

"Colonoscopy seems to prevent two-thirds of deaths on the left side," says Dr. Nancy Baxter, a colorectal surgeon and researcher at St. Michael's Hospital in Ontario, Canada, and lead author of the study. "But there's not much effect at all on the right." A team of researchers lead by Baxter reviewed public health records in Ontario to identify more than 10,000 people, or "case patients," between the age group of 52 to 90. All the patients had been diagnosed with colorectal cancer between January 1996 and December 200. It was found that all these patients had died of the cancer by December 2003.

Yet another research has revealed that colonoscopies can find many round polyps but often fail to detect flat or indented lesions.

There are Physiological reasons which complicate the right-side picture. According to Baxter, stool is more watery on the right side. This makes it difficult for the doctor to see the polyps on this side. Also cancer on the right side is different from the left one. She feels "they're like two different diseases."

Since colonoscopy techniques are improving each day the current colonoscopies may be more accurate than the ones used in 1990s.