Your Colon Cancer Glossary: Words You Need to Know

It’s easy to be baffled by an oncologist’s jargon. Even when you’re well into diagnosis and treatment of colorectal cancer (also known as colon cancer), there may still be words you don’t understand. For instance, when your doctor mentions a “PET,” she’s not referring to man’s best friend. And when she talks about “stages,” it’s got nothing to do with theaters. This guide to the language of colon cancer will help you “talk the talk” and make smart, informed decisions so you can get back to living your life.

Doctor with model of colon

What does the word colon mean?

In your digestive system, food exits the stomach into the small intestine, then passes into your colon, also known as the large intestine. The cecum is a pouch that connects the two. From there, the ascending colon travels up your right side to the transverse colon, which, as its name implies, crosses your upper abdomen to the left side, leading to the descending colon, which travels down the left side of your abdomen to the short, curving sigmoid colon that connects to the rectum.

intestine polyp

Screening Terms You Might Hear

The gold standard of colorectal cancer screening is a colonoscopy, in which a tube is inserted in the colon to look for polyps, overgrowths of the epithelial tissue that lines the intestines. Most polyps are harmless, but they can turn into malignant tumors known as adenocarcinomas. If your doctor sees an area of concern, she’ll take a biopsy—remove a tissue sample—says Samir Gupta, M.D., a gastroenterologist at the University of California San Diego Health. The sample goes to the lab for a histology, a study of the tissue under a microscope to look for cancer.

carcinoma colon

Understanding Your Diagnosis

If it’s determined that you have cancer, the next step is staging—the process of determining if the cancer is contained or has spread within the colon or rectum and to other parts of the body. There are five stages, with Stage 0 being the earliest possible and Stage IV having the worst prognosis, or expected outcome. Stage 0 is also known as carcinoma in situ: These are abnormal cells still in the place where they formed— but keep in mind that they could turn to cancer and spread.

CT scanner

Imaging: How Doctors Take a Closer Look

“During staging we do a multitude of imaging studies for more clues,” says David Rivadeneira, M.D., director of colorectal surgery at Huntington Hospital on Long Island, NY. A CT scan (CT stands for “computed tomography”) uses x-rays to make detailed cross-sectional images that show if the cancer has spread to nearby lymph nodes—immune system glands that help cancer travel—or beyond to other organs.


More Methods of Imaging

An ultrasound relies on sound waves to examine the nearby organs for cancer spread. Magnetic resonance imaging (MRI) uses radio waves and strong magnets to detect spread to the liver, brain, and spinal cord. In a PET scan (positron emission tomography), which is less often used in colon cancer, a slightly radioactive form of sugar that collects in cancer cells is injected into the blood to see where it travels.

ostomy bag

Two Types of Surgery

For people with Stage 0, 1, and 2 colon cancer, surgery alone can be the cure. The procedure to remove part of your colon is known as a colectomy. It may be referred to by the cancer location, such as a right colectomy or transverse colectomy. Many patients today have minimally invasive robotic or laparoscopic surgeries, which can result in a faster recovery, notes Dr. Rivadeneira. A colostomy, a procedure that draws the end of the colon through an incision in the stomach so stool can be collected in an exterior pouch, may also be necessary while you heal, but is usually temporary.


Common Chemotherapy Terminology

People with Stage 3 or 4, and some Stage 2 patients with high-risk colon cancer, will also be given chemotherapy—drugs to kill cancer cells. Chemo after surgery is an adjuvant therapy—which simply means additional treatment that goes after malignant cells that may have been left behind. (Other forms of adjuvant therapy include radiation, hormone therapy, and targeted therapy.) Chemo may also be given prior to surgery to shrink a tumor, which is known as a neoadjuvant therapy (the “neo” indicates it’s a first step before the main treatment, the surgery).

chemo port

Chemo Delivery Methods

Because chemo can go on for months, a port is often implanted in the patient’s chest—it’s a catheter so doctors can deliver meds into the patient’s system without the need for constant IV needle sticks. A PICC line (peripherally inserted central catheter) is similar: It’s a long, implantable catheter that’s placed in the arm rather than the chest.


Important Terms About Advanced Colorectal Cancer

Colon cancer is considered advanced when it’s Stage 4, which means there is metastasis, or spread to distant organs. Typically it spreads to the liver, lungs, and bones, but there also may be perineural invasion—spread to the space surrounding nearby nerves. While that sounds scary, progress in personalized oncology, the development of treatments unique to your specific genes and disease, has made it possible for Stage 4 patients to achieve remission, or no detectable signs of cancer, says Andrea Cercek, M.D., a medical oncologist at Memorial Sloan Kettering Cancer Center in New York City.

radiation therapy

What “Regional Treatments” Are All About

There are also regional treatments with fewer side effects, notes Ryan Merkow, M.D., a surgical oncologist at Northwestern Memorial Hospital in Chicago. One of these is hepatic arterial infusion, which treats liver metastasis by delivering chemo directly to the tumor in the liver via a pump. Radiation therapy, which may be used on rectal cancers and Stage 4 colon cancer, uses high-energy rays to home in on and kill cancer cells, and may be used to ease serious symptoms such as intestinal blockage, bleeding, and pain, or to treat spread to other organs.

Polyp in intestin

More Treatment Terms to Know

Other types of regional treatments may also be used to treat metastasis to the lungs and liver. They include ablation, which basically means to “destroy” the tumor. Radiofrequency ablation uses radio waves delivered via a probe to heat and kill the tumor cells, while cryosurgical ablation uses very cold gas to freeze tumor cells. Embolization is another option: This procedure involves injecting minute particles or beads into selected vessels to block the blood flow feeding the tumor, which allows higher doses of chemo to be delivered directly to it.


Immunotherapy: The Basics

One of the newer cancer treatments, immunotherapy, also called immuno-oncology, uses medications to fire up the immune system, says Dr. Cercek, who’s also a Stand Up to Cancer Colorectal Dream Team investigator. It’s a form of biological therapy, medications made from living sources (rather than chemicals). The two medications currently available are known as checkpoint inhibitors: They block a protein that turns off or slows immune response. Immunotherapy is approved only for Stage 4 patients with tumors with a high level of microsatellite instability (MSI-H), meaning they have a high number of mutations that make them aggressive.

targeted therapy

Educate Yourself on Targeted Therapy

Yet another breakthrough category of treatment, targeted therapy zeroes in on a cancer’s specific genes, proteins, or tissues to block the spread of cancer cells. It’s available to some Stage 4 cancer patients; your doctor will first test your tumor for certain biomarkers—DNA, proteins, genetic mutations—then prescribe appropriate meds. These include EGRF inhibitors, which attack the epidermal growth factor receptors that spur the growth of cancer cells, and VEGF inhibitors, which stop the development of new blood vessels feeding the cancer. VEGF inhibitors are also called angiogenesis inhibitors.


Two Inherited Conditions to Know About

Although rare (they affect about 5% of colorectal cancer patients), there are two conditions caused by genetic defects that can be passed from parent to child. In Lynch syndrome, people inherit a corrupt version of a gene that’s supposed to correct errors in the genetic code. Without this error-correcting capability, DNA mutations multiply, increasing cancer risk. Familial Adenomatous Polyposis (FAP) is caused by a defect in the adenomatous polyposis coli gene that results in the overdevelopment of potentially cancer-causing polyps that can start as early as adolescence.

Stephanie Wood
Meet Our Writer
Stephanie Wood

Stephanie Wood is a award-winning freelance writer and former magazine editor specializing in health, nutrition, wellness, and parenting.