When David Thau, a lobbyist in Washington, D.C., was 34, he periodically experienced pain in his stomach, irregular bowel movements, blood in his stool and vomiting, and he visited doctors who diagnosed him with hemorrhoids and extreme fatigue.
The pain in his stomach got so severe that he couldn’t move from the couch, and he went to an emergency room thinking he had appendicitis. Instead, a CT scan showed he had a 7.5-centimeter tumor in his colon.
Following two colorectal surgeries, one to put a stent into his colon and one to remove the tumor and some lymph nodes, he went to Dana-Farber Cancer Institute in Boston, where he underwent chemotherapy, postoperative treatment and counseling.
“It never crossed my mind that a 34-year-old would have cancer,” says Thau, now 41. “Because there is no history of colon cancer in my family and it obviously wasn’t on the radar of the doctors I saw when symptoms appeared, nobody suggested that I be screened for colorectal cancer.”
He estimates that he had colon cancer for at least two years before he was diagnosed.
Colorectal cancer, which originates in the large intestine (colon and rectum), is the fourth most common cancer in the U.S. for men and women combined and the second leading cause of cancer deaths in men and women, according to the Colorectal Cancer Alliance. But when caught early, it’s highly curable.
Why Is Colorectal Cancer Screening Important?
Once considered primarily a disease of older age, colorectal cancer is rising at alarming rates in people under the age of 50, with 1 in 5 diagnoses occurring in people younger than 55 years old. It’s currently a leading cause of cancer-related death in young people.
Screening for colorectal cancer can save lives — regardless of which screening option you choose — by detecting and removing precancerous polyps or by finding cancers at early, more treatable stages.
[SEE: Colon Cancer Diet.]
Colorectal Cancer Screening Guidelines by Risk Level
The U.S. Preventive Services Task Force recommends:
| Risk Level | Key Risk Factors | Starting Age for Screening | Frequency of Screening |
| Average Risk | Those who are age 45 with no significant personal or family history of the disease | 45 | Regular screenings (continuing every 10 years through age 75) |
| Higher Risk | Those with a family history of colorectal cancer and polyps, inflammatory bowel disease or genetic symptoms | Earlier than 45 | More frequently |
You’re considered at higher risk for the following reasons:
— History. Your family has a history of colorectal or other cancers.
— Bowel disease. If you have bowel disease you are at higher risk.
— Genetic risk factors. About 5% to 10% of colorectal cancer cases are caused by inherited syndrome mutations, such as Lynch syndrome. Up to 30% of cases involve a familial, hereditary or genetic predisposition.
— Childhood cancer survivors. Those who have had cancers at a young age are at higher risk than others.
“It’s important to know your family history of all cancers and to speak with your family to determine if you’re at increased risk,” says Dr. Matthew Yurgelun, a gastrointestinal medical oncologist at Dana-Farber Cancer Institute.
[READ: Why Are More Younger People Getting Cancer?]
Colonoscopy: The Gold Standard for Screening and Prevention
Colonoscopy is the gold standard for colorectal cancer screening and prevention.
“Colonoscopy is the only colorectal cancer screening method that can detect cancer early and remove polyps,” says Dr. Emmanuel Coronel, a gastroenterologist and director of endoscopy at the University of Texas MD Anderson Cancer Center.
During a colonoscopy, a flexible tube with a high-definition video camera at the tip is inserted through your anus into the rectum and colon, allowing doctors to look at the entire colon and rectum and detect abnormalities that may not be causing symptoms.
This is a key advantage, as most colorectal cancers begin as noncancerous, premalignant growths known as colon polyps.
Some polyps can be so subtle that careful examination is vital. Due to this subtlety, some endoscopy units are even equipped with some artificial intelligence tools to assist with polyp detection.
Small polyps can be easily removed during the exam, and any suspicious lesions can be sampled for additional testing.
To prepare for your colonoscopy, you’ll be required to drink a prescription laxative solution and follow food restrictions to completely empty your colon and rectum. Some medications may need to be adjusted or held before the test to ensure that you’ll be clean and will tolerate sedation well.
[READ: Where to Go for Cancer Treatment.]
Stool-Based Testing
Blood vessels in larger colorectal polyps or in cancers are often fragile and easily damaged when stool passes through them. Those damaged vessels bleed into the colon or rectum, but there’s usually not enough blood to be detected by the naked eye. Some at-home stool-based tests can detect hidden blood and signs of colorectal cancer.
Other noninvasive home stool-based tests can detect changes in the DNA or RNA from cells in your stool.
Some of the stool-based tests include the following:
Fecal immunochemical testing (FIT)
A single stool sample can check for hidden blood in the stool from your lower intestines. Your doctor will give you supplies for doing the test at home, which you will send to a lab for results. The test generally requires no special preparation.
Guaiac fecal occult blood test (gFOBT)
A guaiac fecal occult blood test (gFOBT) detects hidden blood in the stool.
Samples from three consecutive bowel movements are placed on a chemically treated card that will change color if blood is present.
Unlike the FIT, gFOBT cannot determine if blood is from the colon or from other parts of the digestive tract, such as the stomach. Some food or drugs can affect the results, so you should avoid the following before you take the samples at home:
— Nonsteroidal anti-inflammatory drugs (NSAIDs). Ibuprofen (Advil), naproxen (Aleve) or aspirin should not be taken for a week prior to testing because they can cause bleeding that could lead to false positive results.
— Vitamin C. More than 250 milligrams a day of vitamin C from supplements, fruit or juices can affect the chemicals in the test and lead to negative results even when blood is present.
— Red meat. Beef, lamb and liver should be avoided for several days before testing to prevent false-positive results.
Multi-targeted stool DNA or RNA tests
Colorectal cancer or polyp cells often have DNA or RNA mutations that can get into the stool. These tests may be able to detect them. Testing is composed of a full bowel movement. No food or medicine restrictions are required before conducting the test, which must be returned to the lab within 24 hours.
Experts recommend that if you’re at average risk or when no signs of concern are detected, stool-based colorectal cancer tests should be administered once every three years. If results show possible signs of cancer, a colonoscopy will need to be performed.
“The specificity of stool-based testing for blood and abnormal DNA has improved over the last few years and can be a good option,” says Dr. Nilo Azad, professor of oncology at The Johns Hopkins School of Medicine in Baltimore.
Blood-Based Testing
Today, there are two blood-based tests approved by the Food and Drug Administration that look for signs of colorectal cancer or precancerous polyps in your blood.
In a clinic, samples of blood are collected and sent to a lab where they’re tested for certain DNA changes that could suggest the presence of cancer or precancerous cells.
However, some experts advise caution with this screening option.
“While blood-based testing may be an option for the future, it’s still in the developmental stage, isn’t highly specific and isn’t yet sensitive enough to detect colorectal cancer,” Azad says.
CT Colonography (Virtual Colonoscopy)
A CT colonography is a noninvasive screening procedure that uses a CT scan to capture cross-sectional images of your large intestines to detect any polyps and other abnormalities.
Prior to undergoing the low-dose radiation scan, a small flexible tube is inserted into the rectum to pump air into the colon and rectum to expand them so that clearer pictures can be taken.
In the scanner, you’ll be asked to hold your breath while one scan is taken with you lying on your back and another is taken when you’re lying on your side or front.
The scans take about 10 minutes and if they show no abnormalities, you won’t need scans for another five years. If an abnormality is detected, you’ll have to have a colonoscopy.
The drawback is that these scans can miss small or hard to see polyps.
Bottom Line
All of these options for colorectal screening are better than not being screened at all. While a colonoscopy is the most reliable, it may not be ideal for everyone. Talk to your doctor about which screening option is the best for you.
“The best screening test is the one that gets done,” Yurgelun says.
More from U.S. News
Home Care vs. Assisted Living: 2026 Costs, Pros & How to Choose
Can GLP-1s Help With Alcohol and Drug Addiction? Research on Cravings & Dopamine
Total Hip Replacement: Costs, Recovery and New Technologies
Colorectal Cancer Screening: Tests, Guidelines & What to Know originally appeared on usnews.com
