As tumorous growths develop in the large intestine, colon cancer grows. Now it is the third most common form of cancer in the U.S.
The colon, or large intestine, is where the body takes out toxic waste water and salt. The waste then passes through the rectum, and exits through the anus through the body.
Colon cancer is the third most common cause of cancer-related death in the United States, too. In addition, in 2019, the American Cancer Society (ACS) predicts that a new diagnosis of colon cancer will be made to 101,420 people in the US.
Healthcare experts suggest attending routine colon cancer screenings beginning at age 50.
Also common is colorectal cancer which describes co-occurring cancer of the colon and rectal cancer. Rectal cancer originates in the rectum nearest to the anus, which is the final few inches of the large intestine.
In this article we look at how colon cancer can be detected and treated, why it progresses and how it can be avoided.
The early stages of colon cancer frequently have no symptoms. Symptoms, however, may become more apparent as they develop.
These signs and symptoms may include:
- diarrhea or constipation
- changes in stool consistency
- loose, narrow stools
- blood in the stool, which may or may not be visible
- abdominal pain, cramping, bloating, or gas
- continual urges to defecate despite passing stools
- weakness and fatigue
- unexplained weight loss
- irritable bowel syndrome
- iron deficiency anemia
This may cause further symptoms in the new region if the cancer spreads to a new place in the body, such as the liver.
Stages
There are various ways to relate cancer to one point. The phases indicate how far a cancer has spread and how large the tumors are.
The phases of colon cancer develop as follows:
- Stage 0: Also known as in situ carcinoma, the cancer is in a very early stage at this point. It has not expanded much further than the colon’s inner layer, and is typically easy to handle.
- Stage 1: The cancer has spread into the next tissue layer but has not penetrated either the lymph nodes or any other organ.
- Stage 2: The cancer has entered the colon’s outer layers but hasn’t spread beyond the colon.
- Stage 3: Cancer has risen across the colon’s outer layers, entering one or three lymph nodes. It has however not spread to distant locations.
- Stage 4: The cancer entered other tissues outside the colon wall. The colon cancer enters remote areas of the body as stage 4 progresses.
Treatment options
Treatment depends on the form and stage of cancer in the colon. A doctor should also take into account an individual’s age, overall health status and other factors when deciding on the appropriate care choice.
Any cancer does not get a single medication. Surgery, chemotherapy, and radiation therapy are the commonest treatments for colon cancer.
Treatment should aim to suppress the cancer, prevent it from spreading, and reduce any unpleasant symptoms.
Surgery
Chirurgy for extracting part or more of the colon is called a colectomy. During this operation, both the section of the colon that houses the cancer and some of the surrounding area may be removed by a surgeon.
They would usually eliminate neighboring lymph nodes, for example, to reduce the possibility of spreading. Instead the surgeon either reassembles the healthy part of the colon or produces a stoma, depending on the severity of the colectomy.
A stoma is an surgical opening in the abdominal wall. Through this opening, waste passes into a bag which removes the need for the colon’s lower portion. That’s known as colostomy.
Many surgical procedures include:
- Endoscopy: This procedure can require a surgeon to remove some small, localized cancers. They’ll insert a small, flexible tube with attached light and video. It will also have a binding to eliminate cancerous tissue.
- Laparoscopic surgery: There are many small incisions in the abdomen that a surgeon makes. This could be an choice for extracting larger polyps.
- Palliative surgery: The aim of this form of operation is to reduce symptoms of untreatable or advanced cancers. A surgeon may seek to relieve any colon blockage, and treat discomfort, bleeding, and other symptoms.
Here, learn more about endoscopy.
Chemotherapy
A cancer-care team must prescribe medicines that conflict with the cycle of cell division during chemotherapy. They do this by preventing the damage to proteins or DNA and destroying cancer cells.
Such therapies are targeted at any rapidly dividing cells, even healthy ones. Typically these can recover from any damage caused by chemotherapy but cancer cells can not.
A cancer surgeon, or oncologist, may usually prescribe chemotherapy if it spreads to treat colon cancer. The drugs move all over the body, and the procedure will take place in stages, and the body has time to regenerate between doses.
Popular Chemotherapy side effects include:
- hair loss
- nausea
- fatigue
- vomiting
Combination therapies often use different chemotherapy forms, or combine chemotherapy with other treatments.
Radiation therapy
Radiation therapy destroys cancer cells by focussing gamma rays of high energy on them. External radiation therapy may be used by a cancer care team which expels these rays from a machine outside the body.
With internal radiation a physician may inject radioactive materials in the form of a seed near the cancer site.
Some of the metals emit gamma rays, such as radium. The radiation can come from high-energy X-rays, too. A doctor may prescribe radiation therapy to shrink a tumor or to kill cancer cells as a stand-alone treatment. Alongside other cancer therapies, it can also be successful.
For colon cancer, cancer care teams tend not to perform radiation therapies in the later stages. They may use them if early stage rectal cancer has penetrated the wall of the rectum or spread to nearby lymph nodes.
Side effects of treatment with radiation may include:
- mild skin changes that resemble sunburn or sun tan
- nausea
- vomiting
- diarrhea
- fatigue
- appetite loss
- weight loss
Most side effects will resolve or subside a few weeks after completing treatment.
Diagnosis
A physician may conduct a detailed physical evaluation and inquire about personal and family medical background.
Often, they may use the following diagnostic methods to diagnose and stage cancer:
Colonoscopy
A doctor inserts a long, flexible tube into the rectum with a camera at one end to examine the inside of the colon.
A individual may need to adopt a 24-48-hour special diet before the procedure. The colon would also need washing with strong laxatives in a cycle known as bowel prep.
If the doctor detects polyps inside the colon, the polyps will be removed by a surgeon and referred for biopsy. In a biopsy, the polyps are examined under a microscope by a pathologist to look for cancerous or precancerous cells.
A related technique, called a flexible sigmoidoscopy, permits a doctor to investigate a smaller portion of the colorectal region. This approach implies less planning. Also, if a sigmoidoscopy does not show polyps, or if they are found within a small region, a complete colonoscopy may not be necessary.
Double contrast barium enema
This X-ray technique uses a substance called the barium to produce clearer colon images than a normal X-ray. A individual must fast for several hours before he or she undergoes an X-ray barium.
A doctor injects a liquid solution through the rectum which contains the element barium into the colon. They follow this with a quick pumping of air to smooth over the layer of barium to produce the most reliable tests.
The colon and rectum X-ray is then performed by a radiologist. In the X-ray the barium appears white, and any tumors and polyps appear as dark outlines.
If a biopsy indicates colon cancer, the doctor can order an X-ray in the chest, an ultrasound, or a CT scan of the lungs, liver, and abdomen to determine the cancer spread.
Upon diagnosis, a doctor will assess the stage of cancer based on the tumor’s size and magnitude, as well as its spread to surrounding lymph nodes and distant organs.
The stage of a cancer will decide the treatment options and will advise the viewpoint.
Prevention
There is no assured solution to colon cancer prevention. Some preventive steps may include:
- maintaining a healthy weight
- exercising regularly
- consuming plenty of fruits, vegetables, and whole grains
- limiting the intake of saturated fats and red meat
People should also consider reducing their alcohol use and stopping smoking.
Screening
Symptoms can not turn up until the cancer is progressing. For this reason the American College of Physicists recommends screening for people between the ages of 50 and 75, including:
- fecal testing once every 2 years
- either a colonoscopy every 10 years or a sigmoidoscopy every 10 years plus fecal testing every 2 years
The appropriate regularity of the screening depends on the level of risk for an person. For advice, consult your doctor.
Causes
Cells typically follow an orderly rising, splitting, and death cycle. However, cancer grows as cells uncontrollably expand and split, and when they don’t die at the appropriate point in their life cycle.
Many forms of colon cancer stem from adenomatous polyps called non-cancerous tumours. Such form on the large intestine’s inner walls.
Cancer cells may spread through the blood and lymph systems, from malignant tumors to other parts of the body.
These cancer cells may expand and invade healthy tissue in a process called metastasis, near and throughout the body. The consequence is a more severe illness which is less treatable.
The exact causes are unclear but there are some possible risk factors for colon cancer:
Polyps
Colon cancer typically grows in the large intestine from precancerous polyps that expand.
The most common types of polyps are:
- Adenomas: These may resemble the lining of a healthy colon but appear different under a microscope. They can become cancerous.
- Hyperplastic polyps: Colon cancer rarely develops from hyperplastic polyps, as they are typically benign.
Any of these polyps may grow into malignant colon cancer if they are not removed during the early stages of treatment by a surgeon.
Genes
Uncontrolled growth of the cells can occur after genetic damage or DNA changes.
A individual may inherit a genetic predisposition towards colon cancer from close relatives, especially if a family member was diagnosed before the age of 60.
When more than one parent has acquired colon cancer, this risk becomes more severe.
The risk of colon cancer also rises with many hereditary disorders, including:
- attenuated familial adenomatous polyposis
- familial adenomatous polyposis (FAP)
- Gardner syndrome, which is a different type of FAP
- Lynch syndrome, or hereditary nonpolyposis colorectal cancer
- juvenile polyposis syndrome
- Muir–Torre syndrome, which is a variant of Lynch syndrome
- MYH associated polyposis
- Peutz–Jeghers syndrome
- Turcot syndrome, which is another variant of FAP
Such genetic characteristics can be achieved without the development of cancer. That is because the cancer won’t grow unless it is caused by an environmental factor.
Traits, habits, and diet
Age is a major risk factor for colon cancer. About 91 percent of people diagnosed with colorectal cancer are older than 50 years. It’s becoming more common in people under the age of 50 though.
Colon cancer has a greater risk of affecting those with unhealthy diets, those with obesity and those who use tobacco.
Since the colon is part of the digestive system, nutrition and diet play a central role in its development.
Low-fibre diets can help. Individuals who consume excessive quantities of the following also have an elevated risk, according to one 2019 review:
- saturated fats
- red meat
- alcohol
- processed meat
Underlying conditions
Some conditions and therapies have ties to increased colon cancer risk.
These include:
- diabetes
- having undergone radiation therapy for other cancers
- inflammatory bowel diseases, such as ulcerative colitis or Crohn’s disease
- acromegaly, which is a growth hormone disorder
Outlook
Using a 5 year survival rate, the ACS estimates the probable probability of a individual surviving.
If a cancer has not spread beyond the colon or rectum, a person is 90 percent as likely as a person without cancer to survive for 5 years after diagnosis.
If the cancer spreads to surrounding tissues and lymph nodes, the survival rate for 5 years will drop to 71%. The prevalence drops to 14 percent if it spreads to distant locations in the body.
Effective diagnosis and care are the most successful means of increasing a person’s outlook for colon cancer.
Q:
Where does colon cancer spread most often?
A:
In stage 4 colon cancer (and rectal cancer), the liver is the most common site of metastasis. Colorectal cancer cells may also spread to the lungs, bones, brain, or spinal cord. __Christina Chun, MPH
Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
