Colon cancer is a type of cancer that begins in the large intestine (colon). The colon is the final part of the digestive tract.
Colon cancer typically affects older adults, though it can happen at any age. It usually begins as small, noncancerous (benign) clumps of cells called polyps that form on the inside of the colon. 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
Colorectal cancer may not present with any symptoms, especially in the early stages. Symptoms during the early stages, may include:
- constipation
- diarrhea
- changes in stool color
- changes in stool shape
- blood in the stool
- bleeding from the rectum
- excessive gas
- abdominal cramps
- abdominal pain
Late stage symptoms
Colorectal cancer symptoms are more noticeable in the late stages (stages 3 and 4). In addition to the above symptoms:
- excessive fatigue
- unexplained weakness
- unintentional weight loss
- changes in your stool that last longer than a month
- a feeling that your bowels won’t completely empty
- vomiting
If colorectal cancer spreads to other parts of the body, may also there’s:
- jaundice, or yellow eyes and skin
- swelling in the hands or feet
- breathing difficulties
- chronic headaches
- blurry vision
- bone fractures
Causes
In general, colon cancer begins when healthy cells in the colon develop changes (mutations) in their DNA. A cell’s DNA contains a set of instructions that tell a cell what to do.With time, the cancer cells can grow to invade and destroy normal tissue nearby. And cancerous cells can travel to other parts of the body to form deposits there (metastasis)
Risks factors
There’s a growing list of risk factors that act alone or in combination to increase a person’s chances of developing colorectal cancer.
Fixed risk factors
- age over 50
- a prior history of colon polyps
- a prior history of bowel diseases
- a family history of colorectal cancer
- genetic syndromes, such as familial adenomatous polyposis (FAP)
- African-American race
Modifiable risk factors
- obesity
- smoking
- alcoholism
- type 2 diabetes
- sedentary lifestyle
diet high in processed meats
Prevention
Screening colon cancer
Doctors recommend that people with an average risk of colon cancer consider colon cancer screening around age 50. But people with an increased risk, such as those with a family history of colon cancer, should consider screening sooner.
Lifestyle changes to reduce the risk of colon cancer
You can take steps to reduce your risk of colon cancer by making changes in your everyday life. Take steps to:
- Eat a variety of fruits, vegetables and whole grains.
- Drink alcohol in moderation, if at all.
- Stop smoking.
- Exercise most days of the week..
- Maintain a healthy weight
Diagnosis
An early diagnosis of colorectal cancer gives you the best chance of curing it.
The American College of Physicians (ACP) recommends screenings for people who are 50 to 75 years old, at average risk of the condition, and have a life expectancy of at least 10 years.
The British Medical Journal (BMJ)Trusted Source recommends screenings for people who are 50- to 79-years-old and whose 15-year risk of developing the condition is at least 3 percent.
If your signs and symptoms indicate that you could have colon cancer, your doctor may recommend one or more tests and procedures, including:
- Using a scope to examine the inside of your colon (colonoscopy). If any suspicious areas are found, your doctor can pass surgical tools through the tube to take tissue samples (biopsies) for analysis and remove polyps.
- Blood tests. No blood test can tell you if you have colon cancer. But your doctor may test your blood for clues about your overall health, such as kidney and liver function tests.
Your doctor may also test your blood for a chemical sometimes produced by colon cancers (carcinoembryonic antigen, or CEA). Tracked over time, the level of CEA in your blood may help your doctor understand your prognosis and whether your cancer is responding to treatment.
Treatment
It depends on the location of the cancer, its stage and other health concerns. Treatment for colon cancer usually involves surgery to remove the cancer. Other treatments, such as radiation therapy and chemotherapy, might also be recommended.
Surgery for early-stage colon cancer
If the colon cancer is very small,then may be recommend a minimally invasive approach to surgery, such as:
- Removing polyps during a colonoscopy (polypectomy).
- Endoscopic mucosal resection
- Minimally invasive surgery (laparoscopic surgery).
Surgery for more advanced colon cancer
If the cancer has grown into or through the colon, may be recommend:
- Partial colectomy. During this procedure, the surgeon removes the part of the colon that contains the cancer, along with a margin of normal tissue on either side of the cancer. This procedure can commonly be done by a minimally invasive approach (laparoscopy).
- Surgery to create a way for waste to leave your body(colostomy). When it’s not possible to reconnect the healthy portions of your colon or rectum, you may need an ostomy. This involves creating an opening in the wall of your abdomen from a portion of the remaining bowel for the elimination of stool into a bag that fits securely over the opening.
Sometimes the colostomy is only temporary, allowing the colon or rectum time to heal after surgery. In some cases, however, the colostomy may be permanent.
- Lymph node removal. Nearby lymph nodes are usually also removed during colon cancer surgery and tested for cancer.
Surgery for advanced cancer
If the cancer is very advanced, the surgeon may recommend an operation to relieve a blockage of the colon or other conditions in order to improve the symptoms. This surgery isn’t done to cure cancer, but instead to relieve signs and symptoms, such as a blockage, bleeding or pain.
Chemotherapy
Chemotherapy involves the use of drugs to kill cancer cells. For people with colorectal cancer, chemotherapy commonly takes place after surgery, when it’s used to destroy any lingering cancerous cells. Chemotherapy also controls the growth of tumors. Chemotherapy 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.
Other medications
Targeted therapies and immunotherapies may also be recommende
