New guidelines released Wednesday recommend American adults start getting colon cancer screenings earlier -- at age 45 instead of 50.
The American Cancer Society said it decided to urge earlier screenings because a study last year found rising rates of colon cancer deaths in people younger than 50.
The new guidelines are for men and women ages 45 to 75 with average risk for colon cancer. The recommendations may differ for people with certain conditions, like Crohn's disease, or a family history of colon cancer.
The American Cancer Society endorses six kinds of screening exams, ranging from inexpensive take-home stool tests performed annually to colonoscopies done every 10 years.
"All of these tests are good tests, and the choice should be offered to patients," said the ACS's Dr. Rich Wender. "The best test is the test that gets done."
Dr. Harsha Polavarapu of Blessing Physician Services in Quincy, who specializes in colorectal surgery, said he thinks the earlier screening recommendation is a good idea based on the studies showing colon cancer is striking "a younger and younger population."
Polavarapu said it makes sense to start the screening process earlier "and catch those marginal patients who are between 40 and 50."
He said early detection is the key to helping someone diagnosed with colon cancer, which is typically confirmed through a colonoscopy -- an examination of the colon using a flexible tube inserted through the rectum. If the exam uncovers the presence of a polyp, a tissue sample from the polyp will be taken to determine if cancer cells are present.
If cancer is not present or if no polyps are found, the patient can usually wait 10 years before having another colonoscopy.
"Our goal is to catch these cancers at the polyp stage where we can take it out completely without any major surgery," he said.
Polavarapu said any type colon cancer screening is helpful, including stool tests that look for microscopic traces of cancer or even CT scans that look for abnormalities in the colon.
"But the colonoscopy is still the gold standard test for screening for colorectal cancer," he said.
"Colon cancer screening is extremely important, and it's something that everybody needs to seriously consider and talk to their primary care doctor about."
The ACS's new guideline is out of sync with guidelines from the U.S. Preventive Services Task Force, an influential government advisory group that kept the initial screening age at 50 in an update two years ago.
The panel reviews evidence and issues advice for a variety of screenings and treatments. It updated its colon cancer guidelines in 2016 and its next review isn't expected until around 2021.
The panel's recommendations drive what screening is covered by insurance under the Affordable Care Act, although 20 states have laws that link coverage to the cancer society's guidelines. It's not uncommon for groups to have slightly different guidelines, although those for colon cancer have been about the same for decades.
Cancer society officials acknowledge the shift to 45 could cause confusion for doctors and patients, but they felt they needed to act now because of the rising number of younger cases.
Polavarapu agreed that the change in guidelines could lead to some confusion, but he feels it's "something that can easily be disseminated in the medical community" through an educational campaign.
Statistics show most colon cancer occurs in adults 55 and older, and the good news is rates of cases and deaths have been falling for decades. Colon cancer, combined with rectal cancer, is the second leading cause of cancer death in the U.S. This year, more than 140,000 Americans are expected to be diagnosed with it, and about 50,000 will die from it.
Doctors will probably look to specialty medical societies to sort out the different guidelines, said Dr. Marcus Plescia, of the Association of State and Territorial Health Officials. But it may take a little while before they offer clear advice.
Some experts have worried about pre-50 risks of colon cancer in some racial and ethnic groups, and at least one specialty society for gastroenterologists has urged screening of black adults starting at age 45.
Others argue that instead of lowering the age for routine screening, more effort should be put into getting more people tested. Only about two-thirds of people 50 and older have been following screening guidelines.
"It's hard enough to get people to do it at all," Plescia noted.
The Associated Press contributed to this report.