According to a new report from the American Cancer Society, rates of colorectal cancer - commonly called colon cancer - are decreasing steeply among older people in the US because of increasing use of colonoscopy screening, which can detect and remove precancerous growths.
Over the last 10 years in the US, colon cancer incidence rates have fallen by 30% among people aged 50 and over, with the largest fall in those over 65.
Meanwhile, use of colonoscopy screening has nearly tripled among those aged 50 to 75 - from 19% in 2000 to 55% in 2010.
These were the key findings of the latest issue of Colorectal Cancer Statistics 2014, which is due to be published in the March/April issue of CA: A Cancer Journal for Clinicians, and for which a companion report is available on the Society's website.
They are being released as part of a new initiative to push colon cancer screening rates up to 80% by 2018.
Screening detects precancerous growths and early stages of colon cancer
Colon cancer is the third most common cancer and the third leading cause of cancer death in the US. Yet because it grows slowly from precancerous polyps - small growths on the inner lining of the colon - there is an opportunity not available with many other cancers to prevent it by finding and removing these growths.
Colonoscopy screening - where the colon is examined with a camera - can also detect any cancer itself in the early stages, increasing the chance of successful treatment.
For the latest figures, the American Cancer Society researchers, led by Dr. Rebecca Siegel, drew on incidence data collected by two national programs: a surveillance program run by the National Cancer Institute and a program of cancer registries run by the Centers for Disease Control and Prevention (CDC).
They found that during the period of 2001 to 2010, overall rates of colon cancer incidence fell by an average of 3.4% per year.
Among the under 50s, colon cancer rates have risen slightly year on year
However, within this average, the trends varied greatly by age. For instance, colon cancer rates fell by 3.9% per year among those aged 50 and over, but they went up by 1.1% per year among the under 50s.
The steady increase in colon cancer among those under 50 is mostly in cases where tumors developed in the distal colon and the rectum, which has been linked to increases in rates of obesity and unhealthy diets, say the report authors.
The most striking fall in colon cancer rates is among those aged 65 and over - where the decline has accelerated from 3.6% per year up to 2008 and then plummeted to 7.2% per year.
The authors suggest the sharper fall in colon cancer rates among seniors - who become eligible for Medicare when they turn 65 - is likely due to higher take up of screening because of universal insurance coverage:
"In 2010, 55% of adults aged 50 to 64 years reported having undergone a recent colorectal cancer screening test, compared with 64% of those aged 65 years and older."
Overall deaths from colon cancer follow similar sharp decline
Rates of death from colon cancer in the past decade follow a similar sharp decline. Between 2001 and 2010, they fell by around 3% a year, compared with 2% in the 1990s.
Dr. Richard C. Wender, chief cancer control officer for the American Cancer Society, says:
"These continuing drops in incidence and mortality show the lifesaving potential of colon cancer screening; a potential that an estimated 23 million Americans between ages 50 and 75 are not benefiting from because they are not up to date on screening."
"Sustaining this hopeful trend will require concrete efforts to make sure all patients, particularly those who are economically disenfranchised, have access to screening and to the best care available," he adds.
Medical News Today recently published an article on the risks, symptoms and importance of screening for colon cancer. The article mentions a recent report from the CDC that says more than 20 million eligible adults in the US have never had the recommended screening for colon cancer, putting them at higher risk of dying from a preventable condition.