Colon Cancer

Colon cancer is also known as colorectal cancer, a term that refers to both colon and rectal cancers. The two are often grouped together because they start in the large intestine. The colon is the final part of the digestive tract, the first five feet of the large intestine, and absorbs water from stool. Colon cancer typically starts as small, noncancerous (benign) polyps on the inner lining of the colon.

Types & Stages

Colorectal cancer arises from the lining of the colon or rectum, usually from cells that secrete mucus. Most colorectal cancers are adenocarcinomas. These cancers start in cells that make mucus to lubricate the inside of the colon and rectum. When doctors talk about colorectal cancer, they’re almost always talking about this type. 

Other, much less common types of tumors can also start in the colon and rectum. These include:

• Carcinoid tumors. These start from special hormone-making cells in the intestine. 
   
• Gastrointestinal stromal tumors (GISTs) start from nerve cells in the wall of the gastrointestinal tract. Some are benign (not cancer). These tumors are most commonly found in the stomach and small intestine. They’re not commonly found in the colon or rectum.
   
• Lymphomas are cancers of immune system cells. They mostly start in lymph nodes, but they can also start in the colon, rectum or other organs. 
   
• Sarcomas can start in blood vessels, muscle layers or other connective tissues in the wall of the colon and rectum. Sarcomas of the colon or rectum are rare. 

Signs & Symptoms

In most cases, colorectal cancer is often symptomless, which is why screening is so important. However, some people do experience telltale signs, which include:

• blood in the stool
• rectal bleeding
• a change in bowel habits, such as more frequent diarrhea or constipation
• ongoing discomfort in the belly area, such as cramps, gas or pain
• a feeling that the bowel doesn't empty all the way during a bowel movement
• weakness or tiredness
• losing weight without trying 

Anyone experiencing these symptoms should speak with their primary care physician.

Diagnosis

Colonoscopy is considered the gold standard for diagnosis because it’s the only test that can identify and treat polyps in the entire colon. If a polyp is detected during screening, it often can be removed and biopsied at that time, eliminating the need for additional procedures. This is called a polypectomy. 

While people often dread undergoing a colonoscopy, recent changes make it a gentler experience. For example, Stony Brook uses many different kinds of bowel preparations—some are even in pill form. Your doctor will determine which preparation you’ll tolerate best. 

Treatment

Colorectal cancers respond well to treatment, which is often relatively uncomplicated. About 30 percent of cases can be treated with surgery alone. Cancers in later stages respond well to chemotherapy and radiation, and overall, the five-year survival rate approaches 65 percent.

Treatment for a very small colon cancer might be a minimally invasive approach to surgery, such as:

• Removing polyps during a colonoscopy, called a polypectomy: If the cancer is contained within a polyp, removing the polyp may remove all of the cancer.
   
• Endoscopic mucosal resection: This procedure can remove larger polyps during colonoscopy. Special tools help remove the polyp and a small amount of the lining of the colon.
   
• Minimally invasive surgery, called laparoscopic surgery, can remove polyps that can't be removed during a colonoscopy. In this procedure, our surgeon makes several small incisions in the abdominal wall then uses a laparoscope—a thin, lighted tube with a video camera at its tip—which projects an image onto a large viewing screen. Guided by the laparoscope, our surgeon operates through tiny surgical “ports” (small tubes placed into the abdomen) using specially designed instruments to take samples from lymph nodes in the area around the cancer.

If the cancer has grown into or through the colon, your surgeon might recommend:

• Partial colectomy, which is surgery to remove the part of the colon that has the cancer. The surgeon also takes some tissue on either side of the cancer. It's often possible to reconnect the healthy portions of the colon or rectum. This procedure can often be done by laparoscopy.
   
• Surgery to create a way for waste to leave the body. Sometimes it's not possible to reconnect the healthy portions of the colon or rectum after colectomy. The surgeon creates an opening in the wall of the abdomen from a portion of what's left of the intestine. This procedure, called an ostomy, allows stool to leave the body by emptying into a bag that fits over the opening. Sometimes the ostomy is only for a short time to let the colon or rectum heal after surgery; then it's reversed. Sometimes the ostomy can't be reversed and stays for life.
   
• Lymph node removal. Nearby lymph nodes are usually removed during colon cancer surgery and tested for cancer.

Causes & Risk Factors

According to the American Cancer Society (ACS), colorectal cancer is the third most common cancer in men and women. Factors that may increase the risk of colon cancer are the same as those that increase the risk of rectal cancer. Colorectal cancer risk factors include:

• A personal history of colorectal cancer or polyps. Your risk of colorectal cancer is higher if you've already had rectal cancer, colon cancer or adenomatous polyps.
   
• Race/Ethnicity. In the United States, Black people have a greater risk of colorectal cancer than do other races.
   
• Diabetes. People with type 2 diabetes may have an increased risk of colorectal cancer.
   
• Drinking alcohol. Heavy drinking increases the risk of colorectal cancer.
   
• A diet low in fiber. Colorectal cancer may be related to a diet low in vegetables and high in red meat.
   
• Family history of colorectal cancer. You're more likely to develop colorectal cancer if you have a parent, sibling or child with colon or rectal cancer.
   
• Inflammatory bowel disease. Chronic inflammatory diseases of the colon and rectum, such as ulcerative colitis and Crohn's disease, increase your risk of colorectal cancer.
   
• Inherited syndromes that increase colorectal cancer risk. These may include familial adenomatous polyposis, also known as FAP, and Lynch syndrome. Genetic testing can detect these and other, rarer inherited colorectal cancer syndromes.
   
• Obesity. People who are obese have an increased risk of colorectal cancer compared with people considered to be at a healthy weight.
   
• Older age. Colorectal cancer can be diagnosed at any age, but most people with this type of cancer are older than 50. The rates of colorectal cancer in people younger than 50 have been increasing, but healthcare professionals aren't sure why.
   
• Radiation therapy for previous cancer. Radiation therapy directed at the abdomen to treat previous cancers may increase the risk of colorectal cancer.
   
• Smoking. People who smoke may have an increased risk of colorectal cancer.
   
• Too little exercise. If you're inactive, you're more likely to develop colorectal cancer. 

Screening

The ACS recommends that people undergo screenings starting at age 45 for most adults. Individuals at high risk should start screenings earlier and have more frequent follow-ups. Get more information about our Screening Colonoscopy Program here.

Stony Brook offers additional screening methods, including:

• flexible sigmoidoscopy, in which the doctor looks inside your large intestine with a long, flexible tube with a camera attached (an endoscope). It goes through your anus and rectum.
   
• barium enemas 
   
• fecal occult blood testing
   
• CT colonography, also known as virtual colonoscopy. This latter method, while less invasive because it uses a CT scan to look at the lining of the colon, still requires bowel preparation. It’s generally used with patients who may have an existing colon blockage or if a colonoscopy carries risks, for example, from anesthesia. Unlike a colonoscopy, in which a polyp can be removed during the screening procedure, during a virtual colonoscopy, if a polyp is detected, you’ll need an additional procedure to treat and biopsy it.