The National Cancer Institute reports that colorectal cancer has become “a leading cause of cancer death” among Americans under age 50.
The good news is that it’s possible to detect colorectal cancers at an early stage when they’re easier to treat and cure! If colorectal screening tests show colorectal polyps or colorectal tumor markers, a colonoscopy may be recommended as a follow-up procedure to confirm if colorectal cancers are present.
This article will help you understand the colon and rectum, how colorectal cancer starts and spreads and the types of colorectal cancers.
What is Colorectal Cancer?
Colorectal cancer is a disease in which tumors form and grow in the colon and rectum. The colon is a long, hollow tube extending from the small intestine to the anus. It’s about six feet long and one inch wide. The rectum is the last few inches of your large intestine—where stools are stored until they’re ready to be passed through the anus.
Most colorectal cancers are adenocarcinomas, cancers that start in cells that are responsible for the mucus that lubricates the inside of the colon and rectum. Some subtypes of adenocarcinoma include signet ring and mucinous. Much less common types of tumors related to colorectal cancer include carcinoid tumors, gastrointestinal stromal tumors (GISTs), lymphomas and sarcomas.
How Colorectal Cancer Starts and Spreads
In colorectal cancer, cells grow abnormally and form a tumor. The tumor can start in any part of the colon or rectum, which is why it’s also referred to as colorectal cancer. It usually starts with polyps, abnormal growths on the lining of the colon or rectum.
Some polyps can progress into cancer over time (usually several years), but not all polyps do. The form of the polyp determines its likelihood of developing into cancer. There are different types of polyps:
- Adenomatous polyps (adenomas): Adenoma refers broadly to any benign tumor of glandular tissue. Adenomatous polyps are the most common type of polyp in the colon, and their prevalence increases with age. Because certain types of polyps can lead to adenocarcinoma, adenomas are classified as a precancerous condition. The three types of adenomas are tubular, villous and tubulovillous.
- Hyperplastic polyps and inflammatory polyps: These polyps are more common but are generally not precancerous. More often, people with large hyperplastic polyps (larger than 1 centimeter) may need evaluation with colonoscopy.
- Sessile serrated polyps (SSP) and traditional serrated adenomas (TSA): These types of polyps are often treated like adenomas and have a higher risk of developing into colorectal cancer.
Colorectal Cancer Screening Tests
Colorectal cancer tests can be divided into two main groups:
- Stool-based tests. These tests are less invasive and check the stool (feces) for signs of cancer. While they are easier for the patient to complete, they may need to be performed more often.
- Visual (structural) exams. These tests involve using a scope (tube-like instrument with a light and tiny video camera on the end) to examine the inside of the colon and rectum for any abnormal areas. These exams also often involve special imaging or x-ray tests.
If you are at high risk for colon cancer, contact Tampa Bay Radiation Oncology today for more information about screening and treatment options. More than a thousand men and women diagnosed with cancer each year turn to our trusted team of cancer specialists. We encourage you to call us, ask us a question or consult with us to get a second opinion so you, too, can experience the difference.