Cancers of the colon and rectum have been declining in older adults in recent decades and have always been considered rare in young people. But scientists are reporting a sharp rise in colorectal cancers in adults as young as their 20s and 30s, an ominous trend.
The vast majority of colorectal cancers are still found in older people, with nearly 90 percent of all cases diagnosed in people over 50. But a new study from the American Cancer Society that analyzed cancer incidence by birth year found that colorectal cancer rates, which had dropped steadily for people born between 1890 and 1950, have been increasing for every generation born since 1950. Experts aren’t sure why.
Rectal cancers are rising particularly sharply, far faster than cancers in other parts of the large intestine or colon. The American Cancer Society estimates about 13,500 new cases of colon and rectal cancers will be diagnosed in Americans under 50 this year, with more than 95,500 cases of colon cancer and nearly 40,000 cases of rectal cancer in all age groups.