Colorectal cancer is a cancer that starts in the colon or the rectum. These cancers can also be named colon cancer or rectal cancer, depending on where they start. Colon cancer and rectal cancer are often grouped together because they have many features in common.
Cancer starts when cells in the body start to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other areas of the body. Doctors have concluded that the increasing consumption of fast food, which is low in fibre, may be a key contributing factor. In India, colon and rectal cancers are seen in relatively young patients, as compared to the western population.
Adenocarcinomas make up about 96% of colorectal cancers. 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. Some sub-types of adenocarcinoma, such as signet ring and mucinous, may have a unfavourable prognosis (outlook).
Other, much less common types of tumours can start in the colon and rectum, too:
Carcinoid tumours: These start from special hormone-making cells in the intestine. Click Here to read more about carcinoid tumours
Gastrointestinal stromal tumours (GISTs): start from special cells in the wall of the colon called the interstitial cells of Cajal. Some are not cancer (benign). These tumours can be found anywhere in the digestive tract, but are not common in the colon.
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. Click here to know more about Non-Hodgkin Lymphoma.
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. Click here to know more about Soft Tissue Sarcoma.
In its early stage, colorectal cancer usually doesn’t have symptoms. It is therefore important to keep up with the tests the doctor recommends for an early detection and correct diagnosis. However, when symptoms do appear, the following are most likely:
A change in your bowel habits, including diarrhoea or a change in the consistency of stool for more than a couple of weeks
Rectal bleeding or blood in stool
Persistent abdominal discomfort, such as cramps, gas or pain
Abdominal pain with bowel movement
A feeling that the bowel doesn't empty completely
Unexplained weight loss and fatigue
Anyone can get colorectal cancer, and doctors often don't know why someone gets it. Although scientists don’t know the exact cause, they do know some of the things that make people more likely to get it. These include:
Age: The disease is most common in people over age 50, and the chance of getting colorectal cancer increases with each decade.
Gender: Colorectal cancer is more common among men. Men and women are equally at risk for colon cancer, but men are more likely to develop rectal cancer.
Polyps: These growths on the inner wall of the colon or rectum aren’t cancer, but they can be precancerous. Polyps are fairly common in people over age 50. One type of polyp, called an adenoma, makes colorectal cancer more likely. Adenomas are the first step toward colon and rectal cancer.
Personal history: If you’ve already had colorectal cancer, you could get it again, especially if you had it for the first time before age 60. Also, people who have chronic inflammatory conditions of the colon, such as ulcerative colitis or Crohn's disease, are more likely to develop colorectal cancer
Family history: If a family member has had colorectal cancer it makes one more likely to get it, too. If that relative was diagnosed when he or she was younger than 45 years old, the risk is even higher. If conditions such as familial adenomatous polyposis, MYH-associated polyposis, or hereditary non-polyposis colorectal cancer run in the family, that raises the risk for colon cancer.
Diet: People who eat a lot of fat and cholesterol and little fibre may be more likely to develop colorectal cancer.
Lifestyle: It is more likely to get colorectal cancer if one drinks a lot of alcohol, smokes, doesn’t get enough exercise, and if they are overweight.
Diabetes: People with diabetes are more likely to develop colorectal cancer than other people.
The main types of treatment for colorectal cancer are surgery, radiation therapy, chemotherapy, targeted therapy, and immunotherapy.
Depending on the cancer stage, these treatments may be combined for a better outcome.