Colorectal cancer — cancers that affect the colon and rectum, the last stops on the digestive tract — is now the leading cause of cancer death in people under 50. This concerning trend of increasing colorectal cancer rates in younger people led the U.S. Preventive Services Task Force to change its colorectal cancer screening recommendations in 2021 to advise an earlier start.
Dr. Rachel Issaka, a gastroenterologist and director of the Population Health Colorectal Cancer Screening Program at UW Medicine and Fred Hutch Cancer Center, wants people to understand how tests and early intervention can prevent colorectal cancer deaths in all ages.
She calls the reason behind the rising colorectal cancer rates in young people “a million-dollar question,” but early studies point to factors such as increased consumption of alcohol and ultra-processed foods, along with obesity.
Issaka discussed colorectal cancer screening options and timing, as well as symptoms that should prompt a visit to the doctor and testing. The conversation below was edited for clarity and length.
Q: Why should people get screened for colorectal cancers?
A: Colorectal cancers are one of the most preventable cancers, and screening is a powerful tool for prevention and early detection. These cancers typically begin as small growths within the colon called polyps, which can progress over time and become cancer. We have very effective ways to detect and remove polyps before they’re cancerous, as well as to catch cancer at its earliest stage when it’s easiest to treat.
Q: When should screening begin?
A: We recommend most average-risk individuals — people who do not have a family history of colorectal cancer or who do not have inflammatory bowel diseases like ulcerative colitis or Crohn’s disease — start colorectal cancer screening at age 45. We define family as first-degree relatives, including parents, siblings and children related by blood.
The current guidelines recommend screening happen between the ages of 45 and 75, but there are exceptions to that rule. People at higher risk, meaning those with a family history of colorectal cancer or with an inflammatory bowel disease, might begin screening earlier.
Q: What are the test options, and how often should screening occur?
A: There are many screening options. Some visual tests, like colonoscopies, look directly at the colon. There are also non-direct tests, including stool tests that look for small amounts of blood in the stool or newer-generation blood tests. The frequency of screening depends on the test and the results. A completely normal colonoscopy needs to be repeated every 10 years. A stool-based test, if completely normal, needs to be repeated annually or up to every three years, depending on the type of test.
If a person chooses to be screened with a test other than colonoscopy, any abnormal test result should be followed by a timely colonoscopy.
Q: What symptoms should prompt someone to get screened?
A: Most colorectal cancers are asymptomatic, which is why we recommend people start screening at age 45, even if they feel perfectly fine.
Symptoms of colorectal cancer might include blood in the stool that may be persistent or intermittent, abdominal pain that is not otherwise explained, unexplained weight loss or changes in bowel movements. For anyone experiencing these symptoms, we recommend a colonoscopy. Health insurance will usually cover screening at any age for people with worrisome symptoms.
Also, pay attention to abnormalities in blood lab work. Iron deficiency anemias are one of the more common signs that we see in people who have colon cancer. If you have anemia, we suggest getting screened with a colonoscopy to make sure colon cancer is not a cause.
Many people don’t like to talk about stool and don’t want to look at their stool, but I tell my patients to make a habit of looking at their stool. You won’t see blood in your stool or know if there are changes in your bowel movements if you haven’t been paying attention.
Q: If I’m under 45, do I need to get screened?
A: For people who are under the age of 45, we recommend that they talk to their relatives to understand their family’s cancer history. We know that certain cancers, such as uterine cancer and Lynch syndrome (a hereditary condition that raises the risk of many cancers), are associated with genetic syndromes that increase an individual’s risk of colorectal cancer. So, understanding your family’s medical history can help your healthcare team to know if you need to be screened earlier.
Q: What percentage of people who should get screened are doing so, and if not, why not?
A: In the United States, our goal is to screen 80% of people between the ages of 45 and 75. However, one in three people who should get screened has not completed screening yet. That’s due to a combination of factors, including lack of insurance, difficulty accessing physicians and the logistics of navigating healthcare systems.
Q: What do you wish everyone understood about screening?
A: Survival from colorectal cancer is greatest when it’s captured early. For people who are diagnosed with this cancer when it’s still within the colon, 90% to 95% of them are alive and well five years after diagnosis. But if the cancer spreads beyond the colon, only about 10% to 13% of people are doing well at that same five-year mark. Don’t delay screening; it could make a significant difference.