Colorectal cancer is the development of malignant cells in the large intestine, which consists of the colon, rectum and anal canal. While colorectal cancer is most commonly found in the sigmoid colon and rectum, it can occur anywhere in the large intestine. At Great Lakes Cancer Care, our experts understand the intricacies of colorectal cancer and what it takes to treat your cancer with expertise and compassion.
Colorectal cancer has no symptoms in its early stages. Tumors can grow slowly over the course of several years, and may only cause symptoms at later stages. Symptoms will also vary depending on the location of the tumor, how long it has been growing and your unique bowel functions. Discuss all symptoms with your doctor, including:
Changes in Bowel Function
- Alternating between diarrhea and constipation
- Increased frequency of bowel movements
- A feeling of incomplete bowel movements
- Stool that is narrower than normal (like a pencil) or differently shaped
- Intestinal discomfort, including cramping, pain, gas and/or bloating
- Intestinal discomfort that is not relieved by bowel movements
Colorectal tumors can cause bleeding in your large intestine. Sometimes, blood is not visible in the stool, especially if the tumor is in the first sections of the colon. This is called occult blood. There are specific tests that can detect occult blood in the stool. Visible blood may appear as:
- Bleeding from the rectum during a bowel movement without other anal symptoms, such as itching, pain, or lumps
- Stool is streaked with blood
- Stool is dark, tarry or black
All rectal bleeding, with or without a bowel movement, should prompt a call to your doctor. Rectal bleeding can be caused by noncancerous conditions, such as hemorrhoids, which may require medical treatment.
Later stages of colorectal cancer may cause:
- Abdominal pain or the sensation of a mass
- Obstructive rectal problems
- Decreased appetite and unintended weight loss
- Intense fatigue, abnormally low energy
- Abdominal or back pain
- Swelling in the legs
- Bone pain
Colorectal cancer is most common in women over 25 years old. Factors that may increase your chance of Colorectal cancer include:
Heredity is perhaps the strongest risk factor for developing colorectal cancer. The two most common forms of inherited colon cancer are:
- Lynch Syndrome: This is a fast-growing form of colorectal cancer. It accounts for about 5% of all colorectal cancer cases. Typically, people with this form develop cancer in their 40s.
- Familial Adenomatous Polyposis (FAP): People with this rare type of colorectal cancer develop hundreds of polyps at a very young age, sometimes as early as their teens. Initially, polyps are benign but do become cancerous over time.
Diets high in fat, particularly fat from animal sources, and low in fiber are associated with an increased risk of colorectal cancer. Eating a diet that is high in fruits and vegetables may help lower this risk.
A sedentary lifestyle increases the risk of colorectal cancer. Even moderate exercise of 30 minutes per day is beneficial.
Smokers are at increased risk of getting colorectal and other cancers. The risk of dying from colorectal cancer is also higher for smokers than nonsmokers.
Three or more alcoholic beverages a day increases the risk of colorectal cancer.
The following medical conditions have been shown to increase the risk of developing colorectal cancer:
- Ulcerative colitis and Crohn's disease: Infection and irritation cause cell changes in the wall of the colon and rectum.
- Colon polyps: Abnormal growths can sometimes turn into cancer if left untreated.
- Previous colorectal cancer: Cancer can recur in new areas of the colon and rectum even if a tumor was surgically removed. The earlier in age you had colorectal cancer, the more likely it is to come back.
- Type 2 diabetes: People with type 2 diabetes have a higher risk of colorectal cancer. Diabetes is also associated with negative outcomes during and after treatment.
- Obesity: Obesity increases the risk of colorectal cancer, particularly when weight is distributed in the waist, rather than on the hips and thighs.
Race and Ethnicity
African-Americans carry the highest risk of developing and dying from colorectal cancer. Ashkenazi Jews are also at a heightened risk due to a specific genetic mutation.
After reviewing your symptoms, medical history and family history, your doctor may recommend several tests to identify abnormalities and confirm a diagnosis, including:
- Digital Rectal Exam: The doctor will insert a lubricated, gloved finger into the rectum, checking for lumps and abnormal areas.
- Hemoccult Test: A small sample of stool is tested by a lab for hidden blood. While blood can be a sign of colorectal cancer, this test does not confirm a diagnosis. There are many reasons blood may be present in stool.
- Blood Tests: When a tumor develops, it releases substances into the blood that can indicate the presence of a tumor. These markers may become elevated in the presence of cancer. Blood tests also evaluate blood cell counts. Low red blood cell counts may be present if there is bleeding in the intestine from cancerous growths.
- Biopsy: The only way to confirm a colorectal cancer diagnosis is with a biopsy. A biopsy is the removal and examination of a tissue sample.
Imaging tests are used to locate tumors and assess their size. Your doctor may recommend one or more of the following imaging tests to get a better understanding of your cancer:
- Barium Enema: A barium liquid is inserted into the rectum by way of the anus. Barium is a metallic compound that helps highlight the image of the lower gastrointestinal tract on an x-ray.
- Sigmoidoscopy: A sigmoidoscope is a thin tube with a light and tiny camera attached. It is inserted into the rectum to view inside the lower colon and rectum. The doctor will use it to search for polyps, tumors and abnormal growths. Polyps and abnormal tissue will be removed and examined.
- Colonoscopy: A thin tube with a tiny camera and light attached is inserted into the rectum to examine the entire inside of both the rectum and colon. Polyps and abnormal tissue will be removed and examined. This is the standard test for examining the colon and rectum.
- Virtual Colonoscopy: A type of CT scan that takes detailed images of the rectum and colon without the insertion of a tube into the colon.
The goal of treatment is to remove as much of the cancer as possible, while preserving colon and/or rectal tissue and function. How your cancer is treated will depend on its characteristics, as well as your age, health and prognosis.
Colorectal cancer treatment includes: