When your colon was biopsied, the samples taken were studied under the microscope by a specialized doctor with many years of training called a pathologist. The pathologist sends your doctor a report that gives a diagnosis for each sample taken. This report helps manage your care. The questions and answers that follow are meant to help you understand the medical language used in the pathology report you received for your biopsy. They do not cover all of the information that would be in a pathology report that would result from having part of your colon removed (resected) to treat colon cancer.
These are all parts of the large intestine. The cecum is the beginning of the colon where the small intestine empties into the large intestine. The ascending colon, transverse colon, descending colon, and sigmoid colon are other parts of the colon after the cecum. The colon ends at the rectum, where waste is stored until it exits through the anus.
A polyp is a projection (growth) of tissue from the inner lining of the colon into the lumen (hollow center) of the colon.
An adenoma is a type of polyp made up of tissue that looks much like the normal lining of your colon although it is different in several important ways when it is looked at under the microscope. In some cases, a cancer can arise in the adenoma.
These are different types of adenomas that are named based on growth patterns that can be seen under the microscope by the pathologist. Once cancer develops in the adenoma, the type of the adenoma is not as important as other factors (see below).
Adenocarcinoma is a type of cancer that starts in the cells that form glands making mucus to lubricate the inside of the colon and rectum. This is the most common type of colon cancer.
These are all terms for the earliest type of cancer that can be found in the colon. Cells that look like cancer cells are only found in the top layers of the polyp or colon lining (called the mucosa). It may be found in an adenoma as it begins to progress toward colon cancer. Because this early cancer does not yet have the ability to spread to other parts of the body, it may be called a pre-cancer, and has probably been caught just in time.
While an adenoma with one of these conditions needs to be completely removed, it is not the same thing as having “colon cancer”, since it cannot spread. Still, patients who have high-grade dysplasia, intramucosal carcinoma, carcinoma in situ, or carcinoma in the lamina propria in their adenomas will need to have future colonoscopies more often to make sure more polyps do not develop.
As colon cancer grows and spreads beyond the inner lining of the colon, it is called invasive. Cancers that are invasive are called true cancers because they can spread to other places in the body.
Differentiation is the grade of the cancer, which is based on how abnormal the cancer cells look under the microscope. Cancers that are higher grade or poorly differentiated tend to grow and spread more quickly. Colon cancer is usually divided into 3 grades:
Sometimes, though, it is just split into 2 grades: well-moderately differentiated (low-grade) and poorly differentiated (high-grade).
Grade is one of the many factors that are used to help predict how likely a cancer is to grow and spread. Poorly differentiated (high-grade) colon cancers tend to grow and spread more quickly than well or moderately differentiated colon cancers. If a polyp contains poorly differentiated adenocarcinoma (cancer), you may need to have an operation to remove part of your colon to make sure that the tumor has not spread outside the colon. You should discuss treatment options with your treating doctor to see what is best for you.
These terms mean that cancer is present in the blood vessels and/or lymph vessels (lymphatics) of the colon, so there is an increased chance that cancer could have spread outside the colon. When vascular, lymphatic, or lymphovascular invasion is present, you may need to have an operation to remove part of your colon to make sure the tumor has not spread outside the colon. You should discuss treatment options with your doctor to see what is best for you.
If your adenoma with invasive adenocarcinoma was not completely removed, then you will need another procedure to remove it. While this is most often an operation performed by a surgeon, your doctor will discuss what treatment options are best for you.
If your adenoma with invasive adenocarcinoma was completely removed, you might not need any further treatment (like surgery) as long as it is not poorly differentiated (see above) and does not have vascular, lymphatic, or lymphovascular invasion (see above). You should discuss treatment options with your doctor to see what is best for you.
Colon polyps are common. Hyperplastic polyps are typically benign (not cancer or pre-cancer) and are not a cause for concern. But the different types of adenomatous polyps (adenomas) need to be removed. Still, if polyps are present in addition to cancer elsewhere in the colon, they don’t usually affect the treatment or follow-up of the cancer.
This series of Frequently Asked Questions (FAQs) was developed by the Association of Directors of Anatomic and Surgical Pathology to help patients and their families better understand what their pathology report means. These FAQs have been endorsed by the College of American Pathologists (CAP) and reviewed by the American Cancer Society.
Last Revised: February 27, 2017
Copyright 2017 Association of Directors of Anatomic and Surgical Pathology, adapted with permission by the American Cancer Society.