Only 37 percent of colorectal cancers are caught when the disease it most curable, before it has spread. This is because many patients do not experience symptoms in these early stages—and that’s why screening is so important. Individuals age 50 and over need to be screened for colorectal cancer. Screening for colorectal cancer can include:
- Digital rectal exam: In this exam, which is performed in a doctor’s office, the doctor inserts a gloved finger a few inches into rectum to search for large polyps and cancers. The downside of this test is that the screening is limited to the lower rectum, and it may be difficult for the doctor to detect small polyps.
- Fecal occult blood test: This test examines a stool sample for blood. While blood in the stool may be a symptom of colorectal cancer, it may also be indicative of another condition, such as hemorrhoids or minor tears.
- Flexible sigmoidoscopy: In this test, the doctor uses a flexible, slender and lighted tube to examine the rectum and the last two feet of the colon, called the sigmoid colon.
- Barium enema: In this test, the doctor evaluates the entire large intestine via x-rays. A contrast dye called barium is placed into the bowel through an enema; this dye fills and coats the lining of the bowel, creating an outline of the rectum, colon and sometimes a small portion of the small intestine. The x-ray can then be used to look for tumors or polyps.
- Colonoscopy: This is the most sensitive colon cancer test. Similar to a flexible sigmoidoscopy, this test uses a colonscope, which is a long, flexible tube attached to a video camera that allows the doctor to view the entire colon and rectum on a monitor. If the doctor notices any polyps, he can either remove them immediately or take samples for biopsy.
- Genetic testing: Patients whose families have a history of colorectal candidate may be candidates for genetic tests that look for genetic markers of cancer.
- Blood tests: These tests may include tests for anemia and the carcinoembryonic antigen assay, which analyzes a stool sample for DNA of abnormal cells.
- Biopsy: The doctor removes a small piece of tissue, which is sent to a lab for analysis.
- Imaging studies: Imaging scans are used to examine internal organs and structures for signs of cancer. These scans can include ultrasounds, CT scans, MRIs, chest x-rays, PET scans and angiographies.
The American Cancer Society recommends that men and women over the age of 50 be regularly screened for colorectal cancer using one of the following methods:
- Yearly stool blood tests
- Flexible sigmoidoscopy every five years
- Yearly blood stool test plus a flexible sigmoidoscopy every five years
- A double contrast barium enema every five years
- A colonoscopy every 10 years