SEATTLE - Between 60 and 70 percent of Washingtonians over age 50 have had colonoscopies to screen for colon cancer, which means at least three out of 10 have not. March is Colorectal Cancer Awareness Month, and there is new medical evidence that these tests pay off. The National Polyp Study followed patients for up to 23 years after they had polyps removed during a colonoscopy.
Dr. Robert Raish with the Knight Cancer Institute at Oregon Health and Science University says not all of the growths are cancerous - but if they're left in place, that can change.
"The time frame is usually pretty long - it can take five, 10 or 15 years before it turns into cancer. So, the general principle of colonoscopic screening is that if you take out a polyp, you prevent the disease."
The study suggests that removing polyps reduces death rates by half. The five-year survival rate drops from 90 percent when colon cancer is caught early to 11 percent after it spreads to other areas of the body.
Claire Greco says the first colonoscopy she had revealed some polyps, which were then removed. Now a veteran of several follow-ups, she says dreading them is not the best mind-set.
"I really consider this relatively easy procedure to go through as a gift to myself and a gift to my family. The momentary inconvenience, which isn't really all that bad, isn't that difficult."
Greco knows people are squeamish about the test, but she says colonoscopies have improved over the years.
"The procedure itself, any more, isn't bad, with the medication that they give you and the environment. You go to sleep - next thing you know, you wake up and you're done. The prep is interesting to go through, but not that bad, really, because again, they have it down to a pretty good science."
After 26 years as an oncologist, Dr. Raish has this advice for anyone avoiding a colonoscopy:
"By far the best way to deal with cancer is to prevent it in the first place. It's not a disease you want to get. You want to see me in the grocery store; you never want to see me in the office."
The Colon Cancer Alliance says more than 140,000 cases will be diagnosed this year, and almost 50,000 people will die from colon cancer in the United States.