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Invasive Adenocarcinoma Of The Colon
(Not Arising In A Polyp)


When your colon was biopsied or resected, the samples taken were studied under the microscope by a specialized doctor with many years of training called a pathologist. The pathology report tells your treating doctor the diagnosis in each of the samples to help manage your care. This FAQ sheet is designed to help you understand the medical language used in the pathology report.

1. What if my report mentions “cecum”, “ascending colon”, “transverse colon”, “descending colon”, “sigmoid colon”, or “rectum”?

The cecum is the beginning of the colon where the small intestine empties into the large intestine. The ascending colon, transverse colon, descending colon, sigmoid colon, and rectum are, in order, other parts of the colon beyond the cecum. The colon ends at the rectum and waste exits through the anus.

2. What is adenocarcinoma of the colon?

Adenocarcinoma of the colon is the most common type of colon cancer (malignant tumor). Adenocarcinoma has a wide range of behavior from cases that are very slow growing with a low risk of causing harm, to cases that are more aggressive and can spread to other areas of your body.

3. What does “invasive” or “infiltrating” mean?

As colon cancer grows and spreads beyond the inner lining of the colon (mucosa), it is called “invasive adenocarcinoma”. It then has the potential to spread to other places in the body.

4. Does this mean that the tumor has invaded deeply and is associated with a poor prognosis?

Not necessarily. On a biopsy, the pathologist cannot typically determine the depth of tumor invasion. The depth of tumor invasion as well as prognosis are typically determined when the entire tumor is subsequently removed.

5. What does differentiation refer to?

Differentiation is the grade of the cancer and is determined by its microscopic appearance. It is an indication of the aggressiveness of the cancer. Colon cancer is usually divided into three grades (well differentiated, moderately differentiated, and poorly differentiated) or sometimes two grades (well-moderately differentiated and poorly differentiated).

6. What is the significance of the grade of colon cancer?

Grade is one of the many factors that helps determine the aggressiveness of a given cancer. Poorly differentiated colon cancers tend to be more aggressive than well and moderately differentiated colon cancers. However, other factors in addition to grade, such as how far the cancer has spread (which cannot be determined on the biopsy) also affect the prognosis.

7. What does it mean if there is vascular, lymphatic, or lymphovascular invasion?

These terms mean that cancer is present in the vessels (arteries, veins, and/or lymphatics) of the colon and that there is an increased chance that cancer could spread out of the colon. However, your cancer could still be very curable depending on other factors.

8. What is a polyp?

A polyp is a projection (growth) of tissue from the inner lining of the colon into the lumen (hollow center) of the colon. Different types of polyps have certain identifiable microscopic appearances. They are usually non-cancerous (benign) but, in some instances, cancer can arise in various types of polyps.

9. What does it mean if, in addition to cancer, my report says there are also other polyps such as adenomatous polyp (adenoma) or hyperplastic polyps?

Polyps are very common and in the setting of cancer elsewhere in the colon will typically not affect treatment and are nothing to worry about.

10. What is the significance if “mucin” or “colloid” is mentioned in my report?

Mucin is produced by the colon to help lubricate the colon. Colon cancers that produce large amounts of mucin are referred to as mucinous or colloid adenocarcinomas. However, on a biopsy specimen, the presence of “mucin” or “colloid” will not determine prognosis or treatment.

11. What does it mean if my biopsy report mentions special studies such as microsatellite instability and MSH2, MSH6, MLH1, and PMS2?

In some colon cancers, special laboratory testing may reveal an abnormality referred to as “microsatellite instability”’. Microsatellite instability is associated with several proteins including MSH2, MSH6, MLH1, and PMS2. Microsatellite instability may be due to a genetic defect that could be present in other family members. At times, additional tests may be necessary and your doctor can help determine when these are needed. Your doctor may use these test results to modify your treatment plan (type, or use, of chemotherapy) or to direct testing of other family members.