What Is Colorectal Cancer?

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About Colorectal Cancer?

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. Colorectal cancer often begins as a growth called a polyp inside the colon or rectum. Finding and removing polyps can prevent colorectal cancer. Explore the links on this page to learn more about colorectal cancer prevention, screening, treatment, statistics, research, clinical trials, and more.

Colon cancer is cancer of the large intestine (colon), which is the final part of your digestive tract. Most cases of colon cancer begin as small, noncancerous (benign) clumps of cells called adenomatous polyps. Over time some of these polyps can become colon cancers.

Polyps may be small and produce few, if any, symptoms. For this reason, doctors recommend regular screening tests to help prevent colon cancer by identifying and removing polyps before they turn into cancer.

Symptoms

Signs and symptoms of colon cancer include:

Colorectal cancer may not present any symptoms, especially in the early stages. If you do experience symptoms, they may include:

  • constipation
  • diarrhea
  • changes in stool color
  • changes in stool shape, such as narrowed stool
  • blood in the stool
  • bleeding from the rectum
  • unexplained weakness
  • passing excessive gas
  • fatigue
  • unintended weight loss
  • abdominal cramps
  • abdominal pain
  • If you notice any of these symptoms, make an appointment with your doctor to discuss a colon cancer screening.
  • A change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool, that lasts longer than four weeks
  • Rectal bleeding or blood in your stool
  • Persistent abdominal discomfort, such as cramps, gas or pain
  • A feeling that your bowel doesn’t empty completely
  • Weakness or fatigue
  • Unexplained weight loss

Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they’ll likely vary, depending on the cancer’s size and location in your large intestine.

causes

Researchers don’t know what causes colorectal cancer yet. However, they do know that colorectal cancer develops when healthy cells become abnormal. The abnormal cells divide and multiply faster than they should and don’t die when they should. This leads to an accumulation of unhealthy cells.

Precancerous growths

Abnormal cells accumulate in the lining of the colon, forming polyps, which are small, benign growths. Removing these growths through surgery is a common prevention method. Untreated polyps can become cancerous.

Gene mutations

Sometimes, colorectal cancer occurs in family members. This is due to a gene mutation that passes from parent to child. These mutations don’t guarantee that you’ll develop colorectal cancer, but they do increase your chances.

Anatomy of the colon and rectum

The colon and rectum make up the large intestine, which plays an important role in the body’s ability to process waste. The colon makes up the first 5 to 6 feet of the large intestine, and the rectum makes up the last 6 inches, ending at the anus (see Medical Illustrations).

The colon and rectum have 5 sections. The ascending colon is the portion that extends from a pouch called the cecum. The cecum is the beginning of the large intestine into which the small intestine empties; it’s on the right side of the abdomen. The transverse colon crosses the top of the abdomen. The descending colon takes waste down the left side. Finally, the sigmoid colon at the bottom takes waste a few more inches, down to the rectum. Waste leaves the body through the anus.

About colorectal polyps

Colorectal cancer most often begins as a polyp, a noncancerous growth that may develop on the inner wall of the colon or rectum as people get older. If not treated or removed, a polyp can become a potentially life-threatening cancer. Recognizing and removing precancerous polyps can prevent colorectal cancer.

There are several forms of polyps. Adenomatous polyps, or adenomas, are growths that may become cancerous. They can be found with a colonoscopy (see Risk Factors and Prevention). Polyps are most easily found during colonoscopy because they usually bulge into the colon, forming a mound on the wall of the colon that can be found by the doctor. About 10% of colon polyps are flat and hard to find with a colonoscopy unless a dye is used to highlight them. These flat polyps have a high risk of becoming cancerous, regardless of their size.

Hyperplastic polyps may also develop in the colon and rectum. They are not considered precancerous.

Diagnosed

Early diagnosis of colorectal cancer gives you the best chance of curing your colorectal cancer. Your doctor will start by getting information about your medical and family history. They’ll also perform a physical exam. The doctor may press on your abdomen or perform a rectal exam to determine the presence of lumps or polyps.

Blood testing

Your doctor may run some blood tests to get a better idea of what’s causing your symptoms. Though there is no blood test that specifically checks for colorectal cancer, liver function tests and complete blood count (CBC) tests can rule out other diseases and disorders.

Colonoscopy

A colonoscopy involves the use of a long tube with a small, attached camera. This procedure allows your doctor to see inside your colon and rectum, and to note anything unusual. During a colonoscopy, your doctor can also remove tissue from abnormal areas. These tissue samples can then be sent to a laboratory for analysis.

X-ray

Your doctor may order an X-ray using a radioactive contrast solution that contains the metallic element barium. Your doctor will insert this liquid into the bowels through the use of an enema. Once in place, the barium solution coats the lining of the colon, and helps to improve the quality of the X-ray images.

CT scan

CT scans provide your doctor with a detailed image of your colon. In the case of colorectal cancer, another name for a CT scan is a virtual colonoscopy.

Prevention

A number of lifestyle measures may reduce the risk of developing colorectal cancer:

Regular screenings: Those who have had colorectal cancer before, who are over 50 years of age, who have a family history of this type of cancer, or have Crohn’s disease should have regular screenings.

Nutrition: Follow a diet with plenty of fiber, fruit, vegetables, and good quality carbohydrates and a minimum of red and processed meats. Switch from saturated fats to good quality fats, such as avocado, olive oil, fish oils, and nuts. Exercise: Moderate, regular exercise has been shown to have a significant impact on lowering a person’s risk of developing colorectal cancer. Bodyweight: Being overweight or obese raises the risk of many cancers, including colorectal cancer.

A study published in the journal Cell has suggested that aspirin could be effective in boosting the immune system in patients suffering from breast, skin and bowel cancer. A gene linked to bowel cancer recurrence and shortened survival could help predict outcomes for patients with the gene – and take scientists a step closer to development of personalized treatments, reveals research in the journal Gut. A study published in Science found that 300 oranges’ worth of vitamin C impairs cancer cells, suggesting that the power of vitamin C could one day be harnessed to fight colorectal cancer

Researchers have found that drinking coffee every day – even decaffeinated coffee – may lower the risk of colorectal cancer.

Treatment

Treatment of colorectal cancer depends on a variety of factors. The state of your overall health and the stage of your colorectal cancer will help your doctor create a treatment plan.

Surgery

In the earliest stages of colorectal cancer, it might be possible for your surgeon to remove cancerous polyps through surgery. During surgery, if the polyp hasn’t attached to the wall of the bowels, you’ll likely have an excellent outlook.

If your cancer has spread into your bowel walls, your surgeon may need to remove a portion of the colon or rectum, along with any neighboring lymph nodes. If at all possible, your surgeon will reattach the remaining healthy portion of the colon to the rectum. If this isn’t possible, they may perform a colostomy. This involves creating an opening in the abdominal wall for the removal of waste. A colostomy may be temporary or permanent.

Chemotherapy

Chemotherapy involves the use of drugs to kill cancer cells. In the case of colorectal cancer, chemotherapy is a common treatment after surgery to destroy any remaining cancerous cells. Chemotherapy also controls the growth of your tumor.

While chemotherapy provides some symptom relief in late-stage cancer, it often comes with side effects that need to be controlled with additional medication.

Radiation

Radiation uses a powerful beam of energy, similar to that used in X-rays, to target and destroy cancerous cells before and after surgery. Radiation therapy commonly occurs alongside chemotherapy.

Medication

In September of 2012, the U.S. Food and Drug Administration (FDA) approved the drug Stivarga (regorafenib) to treat patients with metastatic, or late-stage, colorectal cancer that doesn’t respond to other types of treatment and has spread to other parts of the body. This drug works by blocking enzymes that promote the growth of cancer cells.

Types of cancer in the colon and rectum

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 worse prognosis (outlook).

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

Carcinoid tumors. These start from special hormone-making cells in the intestine. They’re covered in Gastrointestinal Carcinoid Tumors.

Gastrointestinal stromal tumors (GISTs) start from special cells in the wall of the colon called the interstitial cells of Cajal. Some are not cancer (benign). These tumors can be found anywhere in the digestive tract, but are not common in the colon. They’re discussed in Gastrointestinal Stromal Tumor (GIST). 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. Information on lymphomas of the digestive system can be found in 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. They’re discussed in Soft Tissue Sarcoma.

Stages

A commonly used system gives the stages a number from 0 to 4. The stages of colon cancer are:

Stage 0: This is the earliest stage, when the cancer is still within the mucosa, or inner layer, of the colon or rectum. It is also called carcinoma in situ.

Stage 1: The cancer has grown through the inner layer of the colon or rectum but has not yet spread beyond the wall of the rectum or colon.

Stage 2: The cancer has grown through or into the wall of the colon or rectum, but it has not yet reached the nearby lymph nodes.

Stage 3: The cancer has invaded the nearby lymph nodes, but it has not yet affected other parts of the body.

Stage 4: The cancer has spread to other parts of the body, including other organs, such as the liver, the membrane lining the abdominal cavity, the lung, or the ovaries.

Recurrent: The cancer has returned after treatment. It may come back and affect the rectum, colon, or another part of the body.

In 40 percent of cases, diagnosis occurs at an advanced stage, when surgery is likely the best option.

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