The last one
Colorectal cancer rates are rising rapidly among adults in their 20s, 30s and 40s, and the most common warning sign for the disease is blood in the stool, according to a new scientific review.
Rectal bleeding is associated with a five-fold increased risk of colorectal cancer, according to the new analysis, which looked at 81 studies that included nearly 25 million adults under 50 from around the world.
Abdominal pain, changes in bowel habits and anemia are other common warning signs of the disease and should not be ignored, said the researchers, who published the paper Thursday in the journal JAMA Network Open.
Because matter
Colon and rectal cancer rates have increased among young adults while rates have decreased among older adults, who are much more likely to undergo colonoscopies that can detect tumors and precancerous lesions called polyps.
But although millennials born around 1990 are at nearly double the risk of colon cancer than people born in the 1950s, and have a four-fold higher risk of rectal cancer, young people without a strong family history of colon cancer colon are not eligible for colonoscopy until the age of 45.
Doctors may not even notice the warning signs. Anecdotal evidence suggests that because doctors are less likely to suspect malignancies in younger people, they may attribute a symptom like rectal bleeding to a benign condition like hemorrhoids, rather than cancer, said Joshua Demb, a cancer epidemiologist at the University of California, San Diego. and one of the lead authors of the paper.
From the time younger adults first approach a caregiver with a complaint about a symptom until they receive a diagnosis can take an average of four to six months, the analysis found. Because diagnosis is often delayed, younger adults tend to have more advanced disease that is more difficult to treat.
“We need to facilitate early diagnosis, and one way is to identify these warning signs,” said Dr. Demb.
What we don't know
The causal factors driving the increase in colon and rectal cancers in young adults were not addressed in the new analysis and are not well understood.
Colorectal cancer has long been associated with obesity, smoking, a sedentary lifestyle, high alcohol consumption, and diets high in red meat, processed foods, and sugary drinks.
New research exploring the rapid rise of colorectal cancer in young adults is examining other possible causes, including environmental exposures, changes in gut bacteria and the use of certain medications, such as antibiotics.