Early-onset colorectal cancer, defined as being diagnosed when younger than 50, continues to steadily increase in the US and other higher income countries, reveals the latest review by Mayo Clinic researchers. The incidence among people of less than 50 years of age currently accounts for 10 percent of colorectal cancer cases and the patients often present with advanced disease in the left colon. One in six patients has deficient DNA mismatch repair. It is also important to note that most of these rising cases are without a known hereditary basis and have no identifiable cause, the review article stated. The rising cases among the young has also been established by several ongoing researches involving large cohorts and international consortia that aim to identify early life exposures that are most relevant to the development of early-onset colorectal cancer. Therefore, the screening is now recommended to begin at 45 years of age.