Colorectal cancer (CRC) is one of the most preventable types of cancer because screening tests can detect precancerous growths called polyps, allowing for their removal before they turn into cancer. For decades, guidelines advised individuals with an average risk to begin regular screening at age 50. The recommended starting age has now been updated to 45, responding directly to evolving disease patterns.
The Shift to Age 45
The recommendation to lower the starting age for colorectal cancer screening began with the American Cancer Society (ACS), which updated its guideline in May 2018. The more widely influential change came later from the U.S. Preventive Services Task Force (USPSTF).
The USPSTF finalized its updated guidance in May 2021, lowering its official recommendation for screening from age 50 to 45. The task force assigned a “Grade B” rating to screening for adults aged 45 to 49. This specific rating is significant because of its connection to the Affordable Care Act (ACA).
The Grade B recommendation means that most private health insurance plans are mandated to cover the screening procedure without any cost-sharing, such as copayments or deductibles. The USPSTF’s decision effectively removed a financial barrier for millions of people between the ages of 45 and 49, immediately expanding access to preventive care. This policy alignment cemented the new standard for average-risk adults.
The Rationale Behind Lowering the Age
The primary driver for the guideline change was the increase in the incidence of early-onset colorectal cancer, defined as cases diagnosed in people under age 50. While overall CRC rates have been declining for decades in older adults, rates in younger age groups began to rise significantly in the mid-1990s.
This epidemiological trend showed that the disease was increasingly affecting people in their late 40s. Adults born around 1990 have double the risk of colon cancer and quadruple the risk of rectal cancer compared to those born around 1950. By the year 2020, about 11% of colon cancers and 15% of rectal cancers were occurring in patients younger than 50.
This shift prompted medical researchers to use microsimulation modeling, which demonstrated a more favorable balance of benefits versus harms when screening was initiated at age 45 instead of 50. Starting screening earlier allows for the detection and removal of precancerous polyps, reducing both the incidence and mortality rates in this younger cohort.
Defining Average Versus High Risk
The recommendation to begin screening at age 45 specifically applies to individuals considered to be at average risk for colorectal cancer. An average-risk person is someone who has no personal or family history of CRC, precancerous polyps, or certain hereditary syndromes. They also should not have a personal history of inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis.
Individuals are classified as high risk if they have a strong family history, a personal history of inflammatory bowel disease, or a known genetic condition. For instance, having a first-degree relative—a parent or sibling—who was diagnosed with CRC before age 60 elevates a person’s risk significantly.
In these cases, screening should typically begin at age 40, or 10 years earlier than the age at which the relative was diagnosed, whichever occurs first. People with hereditary conditions like Lynch syndrome or Familial Adenomatous Polyposis (FAP) require intensive screening. Those with FAP may need to begin screening procedures as early as age 10 or 12, often with annual examinations.
Available Screening Options
For average-risk individuals starting at age 45, there are two main categories of screening tests available: direct visualization methods and stool-based tests. The gold standard visualization test is the colonoscopy, which is recommended every 10 years if the results are normal. A colonoscopy has the advantage of being both diagnostic and therapeutic, as it can remove any polyps found during the same procedure.
Other visualization tests include CT colonography (virtual colonoscopy), recommended every five years, and flexible sigmoidoscopy, which examines only the lower part of the colon every five years. Stool-based tests are non-invasive and can often be completed at home.
The Fecal Immunochemical Test (FIT) checks for hidden blood in the stool and is typically performed every year. The stool DNA-FIT test, which looks for both blood and abnormal DNA markers, is recommended every one to three years. If any stool-based test returns a positive or abnormal result, a full colonoscopy is required as a follow-up procedure. The choice of test often depends on patient preference and discussion with a physician.