What Is Colorectal Cancer? 

What Is Colorectal Cancer?

Colorectal cancer (also referred to as colon cancer) is a cancer that develops in the colon or the rectum. These parts of the digestive system are also called the large intestine of the gastrointestinal (GI) tract. The digestive system processes food for energy and rids the body of solid waste. Colorectal cancer usually develops slowly over a period of many years. Before a cancer develops, it usually begins as a non-cancerous polyp. A polyp is an abnormal growth of tissue lining the colon or rectum.

Once a colorectal cancer is found, the cancer must be staged. Staging tells your doctor and you if the cancer has spread from the original site to other parts of the body. It is important to know the stage of the disease to plan the best treatment.

Screening/Early Detection

Regular screening can help prevent CRC through diagnosis at an early, curable stage or through removal of precancerous polyps. Your doctor can help you determine at what age to be screened, and what your testing options are. Everyone age 50 or older should be screened for CRC, but if you are at higher risk, screening earlier may be advised. 

Key Statistics on Colorectal Cancer

  • Colorectal cancer is the fourth most common cancer diagnosed in men and in women in the United States, excluding skin cancers and the second leading cause of cancer-related deaths. It is expected to cause about 51,020 deaths (27,640 men and 23,380 women) during 2019.
  • The death rate from colorectal cancer has been dropping over the past several decades. One reason for this is that polyps are being found by screening before they can develop into cancers. Also, colorectal cancer is being found earlier when it is easier to cure, and treatments have improved. There are more than one million (1.3 million) survivors of colorectal cancer in the United States, and this number continues to grow.
  • Ninety percent of people whose colorectal cancer is found at an early stage are alive five years after the diagnosis. However, once the colorectal cancer has spread to nearby organs or lymph nodes, the likelihood of remaining alive five years after the diagnosis is much lower. Only 40 percent of colorectal cancers are found at that early stage. This could be improved greatly if more people followed colorectal cancer screening recommendations.

Colorectal Cancer Signs & Symptoms

Colorectal cancer is often present in people without symptoms. This is why screening for colorectal cancer is so important. The following signs or symptoms, however, might indicate colorectal cancer:

These symptoms may be caused by other benign diseases such as hemorrhoids, infection or irritable bowel syndrome. Patients who experience any of these symptoms for more than a few days, should talk with a gastrointestinal specialist. Our Find a Doctor feature can be used to locate a nearby qualified gastrointestinal endoscopist. 

Certain people are at higher-than-average risk of developing colorectal cancer and should pay particular attention to these symptoms. A personal or family history of colorectal cancer or certain polyps , multiple family members with certain other cancers (uterus, bladder, stomach, etc.) or a history of inflammatory bowel disease are examples of risk factors for developing colorectal cancer.

Patients with a family history of colorectal cancer or certain polyps in a first-degree relative – mother, father, brother, sister or child – should be screened for colorectal cancer starting at age 40 or 10 years before the age of the relative at diagnosis, depending on which is earlier. If colonoscopy screening is selected as the screening method, it should be repeated every five years.

More About Polyps

What causes a polyp to form?

The exact causes of polyps are uncertain, but they appear to be caused by both inherited and lifestyle factors. Genetic factors may determine a person's susceptibility to the disease, whereas dietary and other lifestyle factors may determine which individuals at risk actually go on to form polyps (and later cancers). Diets high in fat and low in fruits and vegetables may increase the risk of polyps. Cigarette smoking, a sedentary lifestyle and obesity may also increase the risk.

How can you prevent polyps from forming?
Few studies have been able to show that modifying lifestyle can greatly reduce the risk of colon polyps or cancer. However, reducing dietary fat, increasing fiber, ensuring adequate vitamin and micro-nutrient intake and exercise may improve general health. Studies have shown that getting adequate calcium may reduce the risk of polyps.

If the polyp is removed, does that mean I am cured?
Removal of a benign polyp does prevent a cancer from developing at that one location, but the patient is at risk to develop polyps at other locations. Close follow-up, often with repeated colonoscopies at set intervals, is needed for these patients. If you have had a polyp removed in the past and change doctors, make sure that your new doctor knows about the polyp history, including pathology results. You  may need a different schedule or frequency of colonoscopies than patients who have never had polyps removed during previous colonoscopies.

Can polyps "fall off" or take care of themselves without having them removed?
Polyps have a slow growth rate, and studies show polyps that are 10 millimeters or less have a fairly stable size over a three-year period. A true polyp will never "fall off" or take care of itself on its own.  The risk of leaving a polyp in place or failing to get the appropriate follow-up colonoscopies is that the polyp could become cancerous.

Is it possible to have colon or rectal cancer without having polyps?
Colorectal cancer can occur without polyps, but it is thought to be an uncommon event. Individuals with long-standing inflammatory bowel diseases, such as chronic ulcerative colitis and Crohn's colitis, are at increased risk for developing colorectal cancer that occurs in the absence of obvious polyps. 

However, colorectal cancer associated with inflammatory bowel disease accounts for less than one percent of all colorectal cancers diagnosed in the United States each year. 

There are also reports that suggest some tiny colon cancers may arise in flat colon tissue that is either entirely normal or contains a small flat area of adenomatous (precancerous) tissue. This type of colon cancer is the exception to the rule, and it may be that a small polyp or abnormal growth preceded the cancer and was too small to see. The vast majority of colorectal cancers arise from pre-existing adenomatous (precancerous) polyps. 

Do all polyps turn into colon cancer?
Polyps can be classified as pre-cancerous or not pre-cancerous based on the types of cells they are made of. Once a polyp is removed during colonoscopy, it is sent to a pathologist to review the polyp under a microscope to see if it is pre-cancerous or not. Generally speaking, there are two types of benign polyps: adenomas and hyperplastic polyps. Adenomatous polyps are made up of pre-cancerous cells. These types of polyps have the potential to turn into cancer over years. Hyperplastic polyps are benign polyps that do not turn into cancer. It is important to complete your screening colonoscopy and to make sure to follow through with your doctor’s recommendation for follow-up colonoscopies so that these pre-cancerous polyps can be removed.  

mom and daughter