We understand how disruptive colon cancer can be to your life. At Stanford Health Care, we work with you to provide relief from your symptoms using advanced treatment techniques.
What is colon cancer?
Colorectal cancer happens when cells grow uncontrollably in the colon or rectum. The cells form small growths, called polyps or tumors. Your doctor can find polyps during screening and diagnostic tests that look for colon cancer. Not all polyps are cancerous, but they can turn into colorectal cancer and spread within the body over time.
During its early stages, colon cancer may not cause any symptoms. Regular screening tests are especially important in preventing and finding colon cancer early on.
What causes colon cancer?
The risk for cancer increases with age, colon cancer most frequently affects people over 45. Genetic disorders may also increase your risk of developing colon cancer. Many colon cancers develop from mutations, or changes, in certain genes.
Knowing colon cancer risk factors and your family history can help you stay ahead of colon cancer. You and your doctor can determine when to start screening for signs of cancer and how often. Screening and leading a healthy lifestyle make colon cancer largely preventable.
Learn more about Cancer Risk Assessment with Genetic Testing and Counseling
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Colon cancer symptoms
Colorectal cancer affects everyone differently. During its early stages, colon cancer may not cause any symptoms. Symptoms may be vague, such as tiredness or dull stomach pain. Sometimes symptoms look like other health conditions, such as infections, hemorrhoids (swollen veins in the anus and rectum), or inflammatory bowel disease (swelling in the digestive tract).
The most common colon cancer symptoms include:
- Cramping or burning stomach pain
- Dark or bloody stool
- Decreased appetite or weight loss
- Fatigue and weakness
- Irregular bowel movements, such as diarrhea, constipation, or narrow stool
- Yellowing of the skin and eyes (jaundice)
- Rectal bleeding
- Vomiting
Colon cancer risk factors
Risk factors are things that increase your chance of having colorectal cancer. Having one or more risk factors does not mean you will get cancer. Sometimes, people with no risk factors develop colon cancer.
- Being overweight or obese
- Drinking alcohol every day
- Eating a diet high in fat and red meat
- Lacking regular physical activity
- Smoking cigarettes
- A history of polyps or colon cancer
- Type 2 diabetes
- Inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease
Genetics may influence your risk of developing cancer. Sometimes changes in genes are passed down in families or caused by elements in the environment. For example, your risk may be increased if someone in your family has had colon cancer. Our Cancer Genetics Program assesses your family history and genetics to provide a better understanding of your risk level.
Colon cancer prevention
Certain healthy habits can decrease your risk of getting colorectal cancer, such as:
- Eating a diet high in fruits, vegetables, and whole grains
- Keeping a healthy weight
- Scheduling regular colon cancer screenings as recommended by your doctor
- Staying active
Colon cancer screening
We offer in-depth risk assessments, specialized surveillance, and screening tests at our Gastrointestinal (GI) Cancer Prevention Program. Our multispecialty team of gastrointestinal doctors, genetic professionals, and cancer doctors helps you stay ahead of cancer.
Screening tests are for people without symptoms of colorectal cancer. They allow your doctor to regularly check for signs of the disease and catch cancer during its early stages if it develops. Colonoscopies are the most common type of screening test, but there are other options. You can discuss with your doctor which test is right for you.
Most doctors recommend routine screening for people aged 45 to 75. If you have any risk factors, your doctor may want to start testing for colon cancer earlier.
Types of Colon Cancer
Several types of colorectal cancer exist, including:
- Adenocarcinoma: The most common colon cancer, this type starts in cells that secrete proteins, called glands. The tumor forms in the lining of the colon or rectum.
- Carcinoids: These tumors start in cells that produce hormones in the large intestine. Often they do not cause symptoms.
- Familial colorectal cancer (FCC): This type affects people with family members who have had colon cancer. The cancer may have been inherited, but there is no known genetic condition.
- Gastrointestinal stromal tumors (GIST): GIST starts in muscle tissue in large intestine. They usually begin as noncancerous tumors and later turn into cancer.
- Lymphoma: This colon cancer starts in structures that are part of the immune system called lymph nodes.
Colon cancer from genetic mutations
Certain genetic diseases lead to colorectal cancer. People with these diseases have changes in their genes called gene mutations. Colon cancer may develop from:
- Juvenile polyposis coli: This condition develops in childhood and causes polyps to form in the digestive tract.
- Peutz-Jeghers syndrome (PJS): PJS also causes polyps to develop in the stomach and digestive tract.
- Turcot syndrome: This disease causes polyps in the colon and rectum.
Some gene mutations are hereditary, meaning they get passed down through multiple generations of a family. Hereditary colon cancers include:
- Familial adenomatous polyposis (FAP): This condition causes hundreds of polyps to develop in the colon and rectum. The polyps turn into cancer with age.
- Hereditary nonpolyposis colorectal cancer (HNPCC): This condition increases the risk of developing cancers, especially colorectal cancer. HNPCC is also called Lynch syndrome.
Colon cancer stages
Colorectal cancer grows over time, becoming more severe and spreading to other parts of the body. Doctors use a system called TNM staging to describe how much the cancer has developed in the body.
In TNM staging, each letter describes an aspect of the cancer:
- Tumor size, which tells how large the tumor has grown and suggests its likelihood of spreading
- Nodes, meaning whether cancer is present in nearby lymph nodes and, if so, in how many
- Metastasis, meaning whether the cancer has spread beyond the lymph nodes
After each letter, an “X” or a number tells you about each aspect. “X” means the aspect can’t be measured, while higher numbers describe more advanced cancer. T ranges from TX-T4, N ranges from NX-N3, and M ranges from MX-M1. For example, you may see T1N0MX.
The TNM stages of colorectal cancer can also be grouped into simpler, less-detailed names:
- Stage 0: Cancer is in its earliest stage and can only be found in the first layer of the colon or rectum lining.
- Stage 1: Cancer can be found in the first and middle layers of the colon or rectum lining.
- Stage 2: Cancer has grown into all layers of the colon or rectum lining, through the wall of the colon or rectum, or to nearby tissues.
- Stage 3: Cancer is in the layers of the colon or rectum lining and has spread to nearby lymph nodes. Lymph nodes are part of the immune system.
- Stage 4: Cancer has spread to other organs far from the colon and rectum, or to the lining of the abdominal cavity (a hollow part of the body above the stomach).
Colon cancer diagnosis
At our Gastrointestinal Cancer Program, our specialists combine their extensive experience and the latest technology to diagnose colorectal cancer. You can trust our experienced team with your cancer care, from recognizing abnormal growths to complex tumors. Having a complete and accurate diagnosis is key to choosing the right treatment.
Diagnostic tests
Based on your symptoms or screening test results, you and your doctor will discuss which diagnostic tests you need. We use several diagnostic methods, including:
- Biopsy: This procedure takes a small tissue sample of a growth for experts to analyze under a microscope. The test looks for cancer or other abnormal cells in the tissue.
- Blood count: This blood test checks red blood cell levels. Low levels of red blood cells (anemia) may indicate a tumor is bleeding.
- Colonoscopy: This test uses a thin, flexible tube with a camera on the end to see inside the entire colon and rectum. As the tube moves through your large intestine, your doctor looks for and removes polyps.
- Sigmoidoscopy: Similar to a colonoscopy, this test looks specifically at the lower part of the large intestine.
- Digital rectal exam: During this exam, your doctor checks the rectum for signs of colon cancer, such as unusual lumps.
- Fecal immunochemical test (FIT): This test finds blood in your stool (a symptom of colon cancer) by looking at the stool under a microscope.
Imaging tests
Your care team may perform imaging tests that provide more information about your diagnosis. The tests look at the stomach and intestines for tumors and other possible problems. Once we determine your diagnosis, imaging tells us more about the growth of the cancer and where it has spread.
Imaging tests may include:
- Virtual colonoscopy
- Magnetic resonance imaging (MRI)
- Ultrasound
- CT Scan
- PET Scan
Next Steps
If your care team finds evidence of colorectal cancer, you and your doctor will discuss the right treatment plan for you. We offer a variety of treatments, personalized to your specific diagnosis and needs.
We’re here to help you and your family each step of the way. You can find support through our Cancer Care Services for every aspect of your care—physical, emotional, spiritual, and social.
Colon Cancer
From common to complex colon cancer, you can trust our specialists for an accurate diagnosis, expert treatment, and compassionate cancer care.
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