What Is Colorectal Cancer?
Medically reviewed by Jay N. Yepuri, MD, MS
Colorectal cancer is the uncontrolled growth of cells in the colon or rectum. It’s the fourth most common type of cancer in the United States. It was estimated that approximately 153,020 cases of colorectal cancer would be diagnosed in 2023, and 52,550 people would die from it.
"Colon" is another name for the large intestine. The rectum is the end of the large intestine that connects to the anus. This part of the body absorbs water and nutrients from food and propels the waste out of the body.
This article will cover the symptoms, causes, diagnosis, and treatment of colorectal cancer. It will also discuss the prognosis and survival rate.
Types of Colorectal Cancer
"Colorectal cancer" is the name for the cancers that begin in the colon or the rectum. While these cancers are pretty similar, there are differences between colorectal and colon cancer.
Most colorectal cancers are adenocarcinomas. These begin in the cells that line the inside of the colon and rectum.
Other rare cancers that can develop in the colon and rectum include:
Small cell carcinoma
Colorectal Cancer Symptoms
Colon cancer symptoms and signs are vague. They’re also signs of many other diseases, including irritable bowel syndrome and hemorrhoids. Just because you have these symptoms doesn’t mean you have colorectal cancer. But you should mention any of them to a healthcare provider.
The warning signs of colorectal cancer include:
Change in bowel habits—including how often you poop, what your poop looks like, and if you have rectal pain or pressure
Diarrhea, constipation, or feeling like you can’t get all your poop out
Blood in your poop that is bright red or very dark
Poop that looks narrower or thinner than usual
Abdominal pain or discomfort—gas pains, bloating, fullness, and abdominal cramps
Losing weight without reason
Constant tiredness, exhaustion, fatigue
Unexplained anemia or iron deficiency
There is no known cause for most colon cancers. Causes and risk factors of colon cancer are varied, but the most important factor is your age, which increases your colorectal cancer risk.
Lifestyle factors that you can control, like drinking alcohol, smoking cigarettes, and having obesity can increase your risk of developing colorectal cancer.
Other relevant risk factors for colorectal cancer include:
A first-degree relative (parent, sibling, or child) who has had colorectal cancer
Having had colorectal adenomatous polyps, colorectal cancer, or ovarian cancer yourself
Having a genetic condition like familial adenomatous polyposis or Lynch syndrome
Having an inflammatory bowel disease like chronic ulcerative colitis or Crohn’s colitis
In the United States, Black people are diagnosed with colorectal cancer more often than those of other races/ethnicities.
If you have any of these symptoms and a healthcare provider thinks you may be at risk of colon cancer, they’ll do a physical exam, take your medical history and do some testing.
Diagnosing colon cancer typically involves:
Tests to look for blood in your stool might include a fecal occult blood test or fecal immunochemical test that you can take at home.
Blood tests often include a complete blood count, liver enzyme test, and a tumor markers test for carcinoembryonic antigen.
Tests that let the healthcare provider see the colon and rectum and take samples (a biopsy) if needed may include a diagnostic colonoscopy or proctoscopy.
Molecular tests of the biopsied tissue include testing for changes in the KRAS, NRAS, and BRAF genes, the HER2 protein, or NTRK genes. They may also test for microsatellite instability or mismatch repair (MMR) genes (MLH1, MSH2, MSH6, and PMS2). EPCAM, another gene related to MSH2, is also routinely checked.
Imaging tests look inside your body to check for and monitor cancer growth. These include a computed tomography (CT) scan, an ultrasound, magnetic resonance imaging (MRI), a chest X-ray, a positron-emission tomography (PET) scan, or angiography.
The diagnostic testing will also help determine your colon or rectal cancer stage. Staging is how healthcare providers compare different cancers and help decide the best treatments. They also can give you an idea of your prognosis.
Treatment of colon and rectal cancer depends on the type and stage. In some cases, colorectal cancer is treatable and even curable.
Treatment may include surgery, radiation therapy, chemotherapy, targeted therapy, and immunotherapy.
Colorectal cancer surgery is the most common treatment for colorectal cancer. Typically, a surgeon removes the tumor, some surrounding healthy tissue, and nearby lymph nodes.
Surgery is often combined with other treatments, including radiation. Radiation is the use of high-energy waves to damage cancer cells. For colorectal cancer, you might get radiation before or after surgery. You'll usually get several treatments over a set period.
A few types of radiation may be used for colorectal cancer treatment, including:
External-beam radiation therapy sends a beam of X-rays to the cancer.
Stereotactic radiation therapy is used when colorectal cancer has spread to the liver or lungs. It sends a large, precise beam of X-rays to a small area.
Intraoperative radiation therapy is a single, high dose of X-rays given during surgery.
Brachytherapy is radiation inserted into the body as "seeds" in the liver to treat colorectal cancer that has spread there.
Chemotherapy given simultaneously with radiation can make it more effective. When used before surgery for rectal cancer, it can reduce the need for a colostomy (creating an artificial opening in the colon to bypass the damaged area, allowing feces to pass) and the chance that the cancer will return.
Chemotherapy is drugs that destroy fast-growing cells, including cancer. Multiple chemotherapy drugs can be combined and given on a specific schedule of medicines and doses over a set period. It may be given before or after surgery or along with radiation.
Chemotherapy drugs used for colorectal cancer include:
Targeted therapy drugs are specific for cancer's genes, proteins, or how it grows and survives. Not all cancers have the same targets—the oncologist (cancer specialist) will run tests to find the genes, proteins, and other factors they may be able to target in your tumor.
Targeted therapies for colorectal cancer include:
Drugs that stop the body from making new blood vessels to starve the tumor of nutrients. These include Avastin (bevacizumab), and similar drugs, Mvasi (bevacizumab-awwb), and Zirabev (bevacizumab-bvzr), Stivarga (regorafenib), Zaltrap (ziv-aflibercept), and Cyramza (ramucirumab)
Drugs that block the epidermal growth factor receptor (EGFR), including Erbitux (cetuximab) and Vectibix (panitumumab)
Drugs that target the BRAF V600E mutation, including Braftovi (encorafenib).
Drugs targeting the HER2 receptor include Tukysa (tucatinib) and Herceptin (trastuzumab)
Drugs that target NTRK fusion, a specific genetic change in some types of cancer. These include Vitrakvi (larotrectinib) and Rozlytrek (entrectinib)
Immunotherapies for colorectal cancer work to engage the immune system in fighting back against the cancer. The most important immunotherapy drugs that treat colorectal cancer are checkpoint inhibitors, which take the brakes off the immune system. Common ones used for these cancers include:
If you're diagnosed with colorectal cancer, your prognosis (outcome) depends on your type of cancer and how advanced it is. Colon cancer survival rates vary by stage and type of cancer.
The National Cancer Institute tracks cancer survival rates in its Surveillance, Epidemiology, and End Results (SEER) database. These rates cannot predict an individual's prognosis, but they provide an overview of how the cancer affects a population. They do not reflect the impact of newer treatments released in the past five years.
SEER tracks survival rates based on three stages: localized, regional, and distant. Localized colorectal cancer has not spread beyond the bowel or rectum. Regional colorectal cancer has spread to nearby lymph nodes or other tissues. Distant colorectal cancer has spread to other organs.
For people diagnosed between 2012 and 2018, the five-year survival rate for all stages of colon cancer was 63%. For localized colon cancer, it's 91%; for regional colon cancer, it's 72%; and for distant colon cancer, it's 13%.
The five-year survival rate for cancers of the rectum was 68%. For localized rectal cancer, it's 90%; for regional rectal cancer, it's 74%; for distant rectal cancer, it's 17%.
Combined, colorectal cancer has a 65% five-year survival rate. That means colorectal cancer is fatal in 35% of people in the first five years after diagnosis. Localized colorectal cancer has a five-year survival rate of 90.9%. Regional colorectal cancer is 73.4%, and for distant, it is 15.6%.
A diagnosis of colon cancer can be overwhelming and emotional. Taking care of yourself physically and mentally is important during this time. Here are some tips to help you cope with colorectal cancer:
Get support from family and friends. Consider joining a support group or finding a cancer therapist.
Educate yourself about your treatment options, side effects, and potential outcomes. This will help you make informed decisions about your treatment and feel more in control of your situation.
Take care of your body by eating a healthy diet and getting regular activity and rest. A strong body can better handle treatment.
Ask for help with everyday tasks like cooking, cleaning, and running errands. Friends and family members are often willing to lend a hand.
Try to stay positive and focus on the things you can control. Surround yourself with positive people and activities that bring you joy.
Work closely with your care team to develop a treatment plan for you. Ask questions and communicate any concerns you may have.
Remember, a colorectal cancer diagnosis is not a death sentence. With early detection and treatment, many people can successfully fight the disease and lead healthy lives. Stay hopeful and take things one day at a time.
Colorectal cancer is a type of cancer that affects the colon or rectum. It is the fourth most common type of cancer in the United States. Most colorectal cancers are adenocarcinomas. These begin in the cells lining the inside of the colon and rectum. Some colorectal cancers are rare types.
Symptoms of colorectal cancer include:
Changes in bowel habits
Blood in the stool
Abdominal pain or discomfort
There is no known cause for most colon cancers. Age, and lifestyle factors, like drinking and smoking, can play a role. A family history of colorectal cancer or certain genetic conditions can increase the risk.
Diagnosing colorectal cancer typically involves a physical exam, testing for blood in the stool, blood tests, biopsies, and imaging tests. Treatment options depend on the type and stage of the cancer. They may include surgery, radiation therapy, chemotherapy, targeted therapy, and immunotherapy.
Colorectal cancer has an overall 65% five-year survival rate. However, the survival rate varies by whether cancer is localized or has spread.