Colorectal cancer cases increase in adults under 50

Colorectal cancer rates are rising in adults younger than 50 with the biggest jump, more than 5 percent, recorded in those ages 20 to 29, a study found.

People older than age 50 began getting tested routinely for the disease in the mid-1980s, leading to a 2.8 percent yearly decline from 1998 to 2005 in adult men overall, according to the American Cancer Society report. Younger Americans, who make up 9 percent of the 146,970 cases expected by the society this year, aren't usually tested for the disease, the second most common cause of cancer death in U.S. adults.

The study was published in the journal Cancer Epidemiology Biomarkers and Prevention. The research didn't identify a cause for the increase. Elizabeth Ward, vice president of surveillance and health policy research at the society, said rising obesity and diabetes rates and diets heavy in red and processed meats are likely culprits.

"The fact that cancer is affecting younger people is worrisome," said Ward, a study author, in a telephone interview. "We want to educate health-care practitioners and the public that this increase is happening, and it may be related to obesity and unfavorable dietary patterns."

From 1992 through 2005, the rate of colorectal tumors climbed 1.5 percent a year in men ages 20 to 49 and 1.6 percent a year in women the same ages, the study found.

The study should raise vigilance about symptoms reported in younger adults, including rectal bleeding, abdominal pain, changes in bowel habits and anemia with blood in the stool, the researchers wrote. Early cancer often doesn't have symptoms, so by the time doctors detected cases in the younger adults, the cancers were invasive, the report said.

Colorectal malignancy is expected to cause 49,920 deaths overall in 2009, the society said.

While tobacco and alcohol are potential risk factors for colorectal cancer, the researchers said they are unlikely to explain the rate increase because alcohol intake has edged down since 1981, and tobacco use takes at least 30 years to lead to colon cancer, the study said.

"I was alarmed reading this. I had no idea this was happening," said Peter Gann, a physician and cancer epidemiologist at the University of Illinois at Chicago College of Medicine.

The American Cancer Society in Atlanta has recommended since the 1980s that adults age 50 and older get routine screening for colorectal cancer. Testing of people under 50 is advised if they have genetic risk factors, a family history of the tumors or inflammatory bowel disease that raise their odds of malignancy, she said.