Key Takeaways
- Colorectal cancer is the second leading cause of cancer death and the third most common cancer in the U.S.
- Timely screening for colorectal cancer is extremely important because finding and removing polyps or abnormalities before they become cancerous reduces the risk by 90%.
- Some risk factors for colorectal cancer can be modified with lifestyle changes; others cannot.
- Do not ignore symptoms of colorectal cancer because if the condition is caught early, a cure is likely.
- Treatments for colorectal cancer depend on the stage at which it is diagnosed.
Emily King of Mobile, Alabama, was diagnosed with colon cancer five years ago at the age of 27. She had experienced some diarrhea, abdominal pain and anemia, but having cancer had never entered her mind. Her first inkling that something might not be right was when she saw blood in her stool. Not long after, she had the cancerous tumor removed, along with a foot of her colon. Her doctors told her that the cancer had spread to 13 lymph nodes in her body.
King underwent 12 rounds of chemotherapy, after which she was told there were no signs of cancer. During a routine checkup six months later, she found out the cancer had reappeared. She underwent another 11 rounds of chemotherapy. Again, it seemed the cancer had disappeared, but three months later it had metastasized to the lungs. Now, she’s in her second clinical trial at Dana-Farber Cancer Institute in Boston.
Colorectal cancer, mostly diagnosed in older people, is the second leading cause of cancer death and the third most common cancer in the United States. In recent years, it’s become the leading cause of cancer death in men under 50 and the second leading cause of cancer death in women under 50.
Cancer diagnoses are rising among young adults, particularly colorectal cancer. By 2030, U.S. incidence rates for early onset colorectal cancer are projected to spike by 90% among those ages 20 to 34 and by 46% for those ages 35 to 49, according to a 2025 study.
“Many symptoms of colorectal cancer can be confused with other, more common conditions, which makes timely diagnosis challenging among young patients. Because some people have no symptoms at all, screening is recommended for individuals at average risk beginning at the age of 45,” says Dr. Kimmie Ng, associate chief of gastrointestinal oncology and founding director of the Young-Onset Colorectal Cancer Center at Dana-Farber Cancer Institute. “One of our concerns, though, is that since the 1990s, we’ve seen an increase in colorectal cancer in people younger than 50, with the steepest rise seen in those in their 20s and 30s, a young group of individuals who are outside the screening guidelines.”
What Is Colorectal Cancer (CRC)? Definition, Colon vs. Rectal Cancer
Colorectal cancer is a type of cancer that develops in the colon or rectum.
Colon cancer
Colon cancer is a type of colorectal cancer that results from an abnormal growth of cells that begins in a part of the large intestine called the colon. The colon is the first and longest part of the large intestine and is part of the body’s digestive system, which includes the esophagus, the stomach and the small and large intestines.
Most colon cancers develop from polyps (growths) in the colon’s inner lining, but not all polyps turn into cancer. Colon cancer screening with a stool-based test or colonoscopy is strongly recommended. A colonoscopy is a procedure that uses a flexible tube with a camera and tools to examine the inside of the colon and to remove any polyps, as needed, before they can become cancerous. If found early, cancerous polyps are very treatable, and cancer is likely to be cured.
Rectal cancer
Rectal cancer, on the other hand, forms in the rectum, the lowest part of the large intestine. Like colon cancer, rectal cancer often develops from polyps in the rectal lining.
The U.S. Preventive Services Task Force recommends that adults at average risk start screening for colorectal cancer at age 45. This guideline was recently lowered from 50 due to the serious rise in young onset cases.
If you have a family member who was diagnosed at a young age, experts encourage you to begin screening 10 years earlier than the age at which your family member was diagnosed. They also encourage genetic testing for patients who are younger or at higher risk due to family history.
Colorectal Cancer Screening: Updated Guidelines and Test Options (Colonoscopy, FIT)
Colonoscopy
A colonoscopy is the most common tool used for screening. Typically performed by a gastroenterologist or colorectal surgeon, this medical procedure examines the inner lining of the colon and rectum to screen for polyps or other abnormalities using a colonoscope, a long catheter with a camera attached to one end.
It requires cleaning stool and other debris from the colon and rectum the day before the procedure to ensure the doctor has a clear view by ingesting a prescribed bowel prep. You are given anesthesia and are sedated for the procedure. During the procedure, the colonoscope is inserted into your anus to look for and remove any polyps or other abnormalities in your colon’s inner lining. If nothing is found during the procedure, you won’t have to have another colonoscopy for 10 years, but if something is found, your doctor may suggest more frequent colonoscopies.
While experts consider colonoscopy to be the most accurate of screening tests for detecting precancerous growths and abnormalities in the colon or rectum, other options are also available.
“Many people either don’t have access to a colonoscopy, have medical conditions that make a colonoscopy risky or are unable or unwilling to undergo the preparation required prior to the test. They need to know that other options exist,” says Dr. Fola P. May, a gastroenterologist at UCLA.
Stool-based tests
There are two types of stool-based tests:
- Fecal immunochemical test (FIT). A FIT is a good choice for people who are at average risk for colon or rectal cancer with no symptoms. You can perform this test in your home, and it doesn’t require a bowel cleanse.
- FIT-DNA test. The FIT-DNA test is a newer stool-based test that looks for both blood and DNA mutations in your stool.
For both tests, an abnormal result would require a colonoscopy to check for polyps and cancers.
Virtual colonoscopy
A virtual colonoscopy uses an advanced computer tomography (CT) scan to generate a 3-D image of the colon and surrounding organs where radiologists can look for abnormalities. The home preparation is similar to colonoscopy preparation, but it’s a good option for those who shouldn’t be sedated (as in traditional colonoscopy) because of preexisting medical conditions. If a polyp or lesion is found, a colonoscopy is required.
Sigmoidoscopy
This procedure looks inside the lower colon for polyps and other abnormalities or cancer using a sigmoidoscope that is inserted through the rectum. A sigmoidoscope is a thin tube-like instrument with a light and lens for viewing and a tool that can remove polyps and anything else that looks unusual to be studied under a microscope. This procedure only looks at the left side of the colon and may still require a bowel prep and anesthesia.
Risk Factors for Colorectal Cancer
Modifiable lifestyle risk factors help reduce your risk and include the following:
- Diet. You can lessen your risk for colorectal cancer by following a healthy diet and limiting red and processed meats. Specifically, a plant-based diet is recommended by National Comprehensive Cancer Network guidelines.
- Obesity. Maintaining a healthy weight is important in reducing your risk for colorectal cancer.
- Smoking. Using tobacco products like cigarettes, chewing tobacco and e-cigarettes will put you at higher risk.
- Alcohol. Consuming even small amounts of alcohol may increase your risk for colorectal cancer.
Nonmodifiable colorectal cancer risk factors include:
- Age. In the U.S., after the age of 50, you are at higher risk for developing colorectal cancer, though in recent years, more people in their 20s and 30s are getting the disease. Risk increases with age.
- Racial and ethnic background. American Indians and Alaska Natives have the highest rates of colorectal cancer in the U.S., followed by African Americans. This is due to disparities in access to health care, environmental exposures and genetic predispositions.
- Health disparities. Many cases of colorectal cancer could be prevented if people were aware of the disease and had access to screening and treatment. Almost one-third of Americans don’t even have access to primary care.
- Sex at birth. It’s unclear why, but men who have colorectal cancer are more likely to die from it than women. Women who have colorectal cancer tend to have right-sided colorectal cancer, especially if they are post-menopausal, implying that the cancer is hormone-related.
- Personal history. If you have had colorectal cancer, your risk of getting it again is increased.
- Inflammatory bowel disease (IBD). Having ulcerative colitis or Crohn’s disease puts you at higher risk for developing colorectal cancer. When you have IBD, your colon is inflamed for long periods of time. Your doctor may suggest you undergo screening at an early age and/or more often than the average person.
- Family history of colorectal cancer. If a first-degree relative (parent, sibling or child) has had colon or rectal cancer, you may be at higher risk, especially if that family member was diagnosed before the age of 50. May says that due to the stigma and embarrassment associated with colorectal cancers, a surprising number of family members are unaware that they have a family history of the disease.
- Inherited syndrome. About 5% of people who develop colorectal cancer have inherited gene mutations that can lead to colon or rectal cancer. They include Lynch syndrome, familial adenomatous polyposis and other conditions that travel in families. If you have 10 or more polyps found in your colonoscopy, then you will be referred for testing.
Top Colorectal Cancer Symptoms: Blood in Stool, Anemia and Changes in Bowel Habits
The most common colorectal cancer symptoms include:
- Blood in the stool. If you see blood in the toilet or on toilet paper after wiping or blood mixed in with the stool, don’t ignore it. Blood in the stool or darker colored bowel movements could indicate bleeding in the intestinal tract.
- Changes in bowel habits. In healthy people, bowel movements typically produce stool that is brown, soft, well-formed and easy to pass. Signs of colorectal cancer can include constipation, diarrhea, narrow stool and mucus in your stool.
- Abdominal pain and bloating. Stomach bloating, distention, cramps or pain in the abdominal bowel region with no known cause that doesn’t go away may be a symptom of colorectal cancer.
- Anemia. Intestinal bleeding may cause anemia in people with colorectal cancer. When a colorectal cancer tumor bleeds, it causes iron loss in the body, which leads to anemia.
- Nausea and vomiting. Nausea and vomiting, like all colorectal cancer symptoms, may also be symptoms of other problems. If you’re vomiting for no reason and it continues for 24 hours, seek medical attention.
- Unintentional weight loss. Unexplained significant and ongoing weight loss could be a sign of colorectal cancer. See your doctor if you have lost at least 10% of your body weight in six months unintentionally.
At the early stages of colorectal cancer there may be no symptoms.
Some symptoms can mimic those of less serious conditions. For example, blood in the stool can sometimes be mistaken for hemorrhoids.
Unfortunately, doctors tend to attribute colorectal cancer symptoms to other, less serious conditions, and colonoscopies for people under the age of 45 are difficult to access, which can lead to missed diagnoses, says Dr. Nicholas DeVito, a medical oncologist and assistant professor of medicine at Duke Cancer Institute in Durham, North Carolina.
In an era when there is rising early-onset colorectal cancer, this can be extremely problematic.
Types of Colorectal Cancer: Understanding Adenocarcinoma and Other Tumors
The following are types of colorectal cancer:
- Adenocarcinoma. Approximately 90% of colorectal cancer cases are adenocarcinoma that develops in the cells of the epithelial or inner lining of the large intestine and can spread deeper to other layers of the intestine.
- Carcinoid tumors. These tumors start in the cells that normally produce hormones in the large intestine. They usually tend to grow slowly over many years. There can be more aggressive versions of neuroendocrine tumors that develop.
- Gastrointestinal stromal tumors. This is a soft tissue sarcoma that starts in the muscle layer of the large intestine.
- Lymphoma. Lymphoma usually starts in the lymph nodes, but it can sometimes start in the white blood cells of the colon. It usually arises in patients with chronic suppression of their immune system.
Colorectal Cancer Diagnosis: Biopsy, Scans and Blood Tests
Depending on your symptoms and screening tests, a diagnosis will be made in the following ways:
- Biopsy. A small sample of a growth or tissue is obtained through a colonoscopy and analyzed under a microscope to look for cancer or precancerous polyps.
- Imaging scan. An MRI, PET or CT scan may be used to determine the stage of cancer and whether it has spread to other areas of the body.
- Complete blood count. This measures the number and size of the different cells in your blood.
- Comprehensive metabolic panel. This will give you information about how your body uses food and energy and the balance of certain chemicals in your body.
- Carcinoembryonic antigen test. This measures a blood protein that can be increased due to some cancers.
- Iron test. Iron studies, such as a ferritin blood test, are also suggested if you have low red cells found on your complete blood count, as iron deficiency anemia is a common sign of colorectal cancer.
Stages of Colorectal Cancer: From Stage 0 to Stage 4 Metastasis
Colorectal cancer staging is determined by the size of the tumor, where it is and whether it has spread to other organs (metastasis). Staging is important because it helps determine treatment.
The following are the stages of colorectal cancer:
- Stage 0. Cancer is in the earliest stage and consists of precancerous or abnormal cells in the innermost lining of the colon wall. This stage is also called “in situ,” which means “in its original place.” This can be managed by a gastroenterologist.
- Stage 1. Cancer has grown into the wall of the intestine, but it hasn’t spread to the lymph nodes. This is either managed by a surgeon or gastroenterologist.
- Stage 2. Cancer has spread farther into the wall of the intestine, but it hasn’t spread to the lymph nodes. This is either managed by a surgeon and sometimes requires a referral to a medical oncologist.
- Stage 3. Cancer has spread outside of the colon to nearby lymph nodes that are part of the immune system. This is managed by a surgeon and medical oncologist.
- Stage 4. Cancer has spread to other organs, such as the liver, lungs or ovaries, far from the colon or to the lining of the abdominal cavity (hollow part of the body above the stomach). This can sometimes be managed by a surgeon with the involvement of a medical oncologist as well.
Colorectal Cancer Treatment Options: Surgery, Chemotherapy, Targeted Therapy and Immunotherapy
Once the stage of cancer is determined, a strategy for treatment can be planned and implemented.
The following are some the treatments available for colorectal cancer:
- Surgery. Surgery is the most common colorectal cancer treatment and ranges from procedures for early-stage cancer to those for more advanced cancer. Here are some of those surgical procedures:
- Polypectomy. If cancer is contained within the polyp, it can be removed during a colonoscopy.
- Partial colectomy. This is also called colon resection surgery. A cancerous part of the colon and some surrounding areas are removed, and your colon is reconnected.
- Surgical resection with colostomy. This procedure is like a partial colectomy, but healthy sections of the colon can’t be reconnected. Instead, your bowel is moved to an opening in your abdominal wall and your feces is collected in a bag.
- Liver debulking and resection. For selected patients, this can sometimes lead to cure and should be discussed with a multidisciplinary approach.
- Chemotherapy. Chemotherapy is a cancer treatment that uses strong drugs to try to shrink a tumor to make it easier to remove. It also may be used after surgery to kill any unseen remaining cancer.
- Radiation. Radiation uses energy beams from X-rays, protons or other sources to kill cancer cells. Most often used to treat rectal cancers, it’s sometimes used to treat a cancer that’s growing into an adjacent structure.
- Targeted therapy. This therapy uses lab-created antibodies that attach to specific targets on cancer cells to target genes, proteins and tissue that help colorectal cancer cells grow. It can be used with chemotherapy or by itself, depending on the drug and mutation.
- Immunotherapy. For certain tumors, when cancer cells have tested positive for specific gene changes, immunotherapy uses your own immune system to kill cancer cells. It can be used before surgery, to treat colorectal cancer that’s come back after surgery or to treat cancer that can’t be removed with surgery.
- Radiofrequency ablation. A minimally invasive procedure, this technique uses heat to destroy cancer cells. In colorectal cancer, it’s sometimes used to treat liver metastases.
- Clinical trials. Clinical trials are research studies that test how well new medical treatments work. Patients enroll in them if their doctors believe they’ll have a chance of improving their condition. Contrary to common belief, clinical trials are not treatments of last resort. They, in fact, may be a first choice of treatment for certain patients.
- Palliative treatment. Palliative care is specialized medical care for people who have advanced colorectal cancer and can be administered at any age and any stage of your illness with or without other treatments. The goal is to relieve the symptoms and stress of illness.
All patients should get a second opinion and, if possible, be treated at a cancer center where there’s greater access to cutting-edge therapies, technology, research and clinical trials, advises Dr. Ashley Hardy, a surgical oncologist at Northwestern Medicine Regional Medical Group in Illinois.
Health Care Providers for Colorectal Cancer
Colorectal Cancer Awareness
Many individuals – particularly young adults and those with limited access to health care – often overlook symptoms and remain unaware of colorectal cancer risk factors.
Because those under 45 are not yet eligible for routine screening, they must be their own advocates for their health by recognizing warning signs and requesting a gastroenterology referral for any new, persistent GI symptoms.
Without increased public health campaigns targeting these high-risk groups, patients will continue to be diagnosed at more advanced stages.
