Where to go for more information:

American Cancer Society

http://www.cancer.org/

Centers for Disease Control and Prevention

http://www.cdc.gov/cancer/colorectal/

The Colon Club

http://www.colonclub.com/

Colon Cancer Alliance

http://www.ccalliance.org/

Shaye Dunn thought it was a mistake. Tests showed she had colon cancer.

“Oh no, that’s got to be wrong,” the Fairburn woman said of her diagnosis a decade ago. “Isn’t this an old person’s disease?”

Indeed, Dunn was considered a low risk for colon cancer, which is the third-most commonly diagnosed cancer in both men and women. Colorectal cancer is also the third-leading cause of cancer death in men and women combined.

But colorectal cancer often occurs in older adults — 90 percent of colon cancer cases and 94 percent of colon cancer deaths occur in people 50 and over, according to the American Cancer Society.

It’s estimated colorectal cancer will kill more than 50,000 people in the U.S. in 2014, including 1,480 in Georgia. Screening has been proven to save lives, discovering polyps before they become malignant.

No one in Dunn’s immediate family had colon cancer. She exercised and had a pretty healthy diet. And she was young, just 36 at the time.

“It’s ignorant to think that just because of your age, you can’t get cancer,” said Dunn, a human resources specialist at Delta Air Lines. “Now I tell everyone to get screened if you have GI (gastrointestinal) problems.”

That’s especially true for her older friends and relatives.

One of her mother’s friends, who is in her 70s, took Dunn’s advice. In an ensuing colonoscopy, Dunn said doctors found a precancerous polyp. “Don’t keep putting it off, do it now,” she said.

Others are apparently getting the message. But it’s not enough, say health officials.

Incidents of colon cancer in the United States has fallen 30 percent in the last decade or so among adults 50 and older, in large part because more screening. The largest drop occurred in people over 65, according the American Cancer Society.

Dr. Otis W. Brawley, chief medical officer for the American Cancer Society, attributed the drop largely to screening with both fecal occult blood testing and colonoscopy.

“There has been almost a halving of the death rate since the mid 1980s, again due to screening and more effective treatment,” he said. “Screening for this disease can find precancerous polyps which, when removed, prevents a cancer.”

Efforts are underway to encourage more people 50 and older to get tested. Although there has been a decline in incidence of colorectal cancer, research shows about 65 percent of adults have been screened and even fewer are up to date.

The National Colorectal Cancer Roundtable, which the American Cancer Society helped to found along with the Centers for Disease Control and Prevention, recently kicked off an “80 percent by 2018” campaign, which strives to increase the number of adults getting screened.

“We stress screening with FOBT and colonoscopy,” said Brawley. “There is a myth that the only good screening is colonoscopy. The best test is the test that fits your lifestyle. FOBT is inexpensive and ironically, the science to support it is stronger than the science supporting colonoscopy. That is not to say colonoscopy is a bad test. Sigmoidoscopy, which looks at the last half of the colon, is also a reasonable alternative.”

Dunn first went to the doctor after she started rectal bleeding one morning as she prepared for work. She had experienced bouts of nausea, but thought it was stress related.

After her cancer diagnosis, doctors removed a half-foot of her colon and followed up with six months of chemotherapy. About a year later, doctor’s discovered the cancer    had metastasized to her lung, but after surgery and more chemo, she is in remission.

Discovering colon cancer in someone younger than 50 is not common, but it’s also not “unheard of either,” said Dr. Harry Liberman of Atlanta Colon and Rectal Surgery in Marietta. He said if someone has a close relative who had colon cancer, it is wise to get tested earlier.

He said symptoms include blood in the stool, a change in bowel habits and weight loss.

“It’s about a physician paying close attention to a patient’s complaints in addition to paying close attention to a patient’s history,” he said.

Doctors are encouraged by promising new treatments and ways to make diagnosis earlier and less invasive.

Dr. Bassel El-Rayes, associate director for clinical research at the Winship Cancer Institute at Emory University and a colon cancer expert, said new drugs for treating colon cancer are being tested at Winsthip, including those that target the cancer specifically and those that help boost the immune system.

That extends to research in screening, including methods that are less invasive and can detect problems earlier.

“It’s a very preventable disease, if people undergo screening if recommended,” El-Rayes said. “There will always be colon cancer but I think we can diagnose it early. We can eliminate death.”

Summed up the American Cancer Society’s Brawley: “The best test is the one you get.”