Published on Sep 08, 2020 and last reviewed on Mar 02, 2023 - 6 min read
Cancer arising from the inner wall of the large intestine or colon is called colon cancer. To know more about colon cancer, continue to read the article.
The type of cancer originating in the large intestine, or the colon, is called colon cancer. The large intestine is the last part of the digestive system. This cancer most commonly affects older adults, but it can occur at any age. Colon polyps, which are small, noncancerous clumps of cells, are usually how this cancer begins. Some of these polyps can turn cancerous over time.
As polyps are quite small and produce very few or no symptoms, it is advised to get regularly screened to prevent colon cancer. Polyps can be identified and removed before they form cancer. Various treatment options are also available for colon cancer, such as surgery, radiotherapy, and chemotherapy.
The term colorectal cancer is used to describe cancer of both the colon and rectum (the end of the large intestine). Its stages are:
Stage 1 - Cancer has spread to the colon or rectal mucosa but not to the walls of the organ.
Stage 2 - Cancer has spread to the walls of the colon or rectum but not to the lymph nodes or adjacent tissues.
Stage 3 - Cancer has reached the lymph nodes but not other body parts. Generally, it involves one to three lymph nodes.
Stage 4 - Cancer has spread to organs like the lungs.
Most people do not experience any symptoms during the early stages of colon cancer. In case symptoms occur, they vary depending on the size of the cancer and its location. The early signs and symptoms of colon cancer are:
Bowel movements keep changing. The stools' consistency changes and the patient might have diarrhea or constipation.
Blood in stools.
Abdominal pain or discomfort.
The symptoms associated with stage 3 or 4 are:
Unintentional weight loss.
Patients will feel as if their bowels have not completely emptied.
If cancer cells spread to other parts of the body, then the symptoms might include the following:
Yellowish discoloration of the skin and sclera (jaundice).
Feet and hands swelling.
Anyone experiencing the above symptoms persistently should book an appointment with their doctor. One should get screened for colon cancer. It is recommended to begin regular screening from 50 years of age. If someone has a family history of this disease, the doctor might ask to start screening early.
Doctors are still trying to find the exact cause of this cancer. Even though the exact cause is not known, the following are some of the factors that increase the risk of developing colon cancer.
Polyps - Polyps are precancerous growths formed by the accumulation of abnormal cells in the lining of the colon. These are usually small and benign; if left untreated, they can become cancerous. The following are some common types of polyps in the large intestine:
Adenomas - They resemble the healthy cells that line the colon and can turn cancerous.
Hyperplastic polyps - They are typically benign and generally do not turn cancerous.
The best way to prevent it is by getting it surgically removed.
Gene Mutations - Mutations of specific genes can make members of a family more prone to this cancer. Genetic damage or changes to DNA can cause the cell to grow uncontrollably. If any family members have been diagnosed with colon cancer, they must be screened at regular intervals.
Age - Almost 90 percent of patients who have been diagnosed with colon cancer are above the age of 50 years. But, it is increasingly becoming common in people under the age of 50 years.
Lifestyle - People with inactive lifestyles are more prone.
Obesity - Overweight and obese individuals are at risk.
Smoking and Alcoholism - Using tobacco products and binge drinking increases the risk.
Diet - A recent study showed that people who consume a diet rich in saturated fats, red meat, processed meat, and low in fiber are more prone to colon cancer.
Underlying Conditions - Diabetes, radiation therapy for other cancers, inflammatory bowel diseases, and acromegaly.
As this cancer does not produce symptoms in the early stages, doctors recommend screening tests to look for signs of colon cancer or polyps. If a person is not in the high-risk group, these screening tests should be started at around 50 years, and if a person is in the high-risk group, then screening should be started earlier.
The doctor will first ask the patient about his family history, symptoms, and medical history. He or she will then perform a physical examination by pressing on the abdomen. Then the patient will be asked to get the following tests done:
Blood tests - To rule out other conditions that can result in similar symptoms. They will ask for liver function tests (LFT) and a complete blood count (CBC)
Colonoscopy - A long flexible tube with a camera attached to one end is inserted inside the colon through the rectum. This can help diagnose polyps and other growths.
Biopsy - If needed, the doctor might remove tissue from any abnormal growth during a colonoscopy. This tissue will then be sent for laboratory testing.
Double-Contrast Barium Enema - The bowels will be coated with a barium solution, and then X-rays will be taken.
CT (Computed Tomography) scan - This provides a more detailed image of the colon.
Depending on the stage of cancer and the patient’s general health, the various treatment options include:
For Early- Stage Cancer: A minimally invasive surgery, such as -
Polypectomy - Small and confined polyps are removed during a colonoscopy.
Endoscopic Mucosal Resection - If the polyps are larger, then the doctor might use special tools to remove the polyps and a little of the inner lining of the colon during a colonoscopy.
Laparoscopic Surgery - For polyps that cannot be removed during a colonoscopy, surgery is done by inserting special instruments through several small incisions in the abdominal wall.
Partial Colectomy- Partial Colectomy is the treatment option in cancer cases that have grown into the colon. The part of the colon that contains the cancer is removed. If the doctor is not able to reconnect the healthy portions of the colon, the surgeon performs an ostomy. An opening will be created on the wall of the abdomen, through which stool is eliminated to a bag outside the body. The nearby lymph nodes are also removed.
For Advanced Cancer - In advanced cases, where cancer has spread to other body parts, the doctor will perform surgeries to relieve signs and symptoms. But these surgeries will not cure cancer.
2) Chemotherapy - Medicines are used to destroy cancer cells and reduce the rate of recurrence.
3) Radiation Therapy - Powerful X-rays and protons are used to destroy cancer cells.
The use of chemotherapy and radiation therapy can shrink cancer, which makes it easier for the surgeon to remove it. If cancer is inoperable, then these treatment options provide symptomatic relief.
The other treatment options include targeted drug therapy, immunotherapy, and palliative care.
The following tips might help lower the risk of colon cancer:
The diet should include fruits, vegetables, and whole grains because vitamins and minerals are abundant in them.
Keep the weight under check. A treatment plan to lose weight should be made after consulting the doctor for those who are overweight.
Avoid binge drinking and limit the consumption of alcohol.
Try to exercise at least four days a week for a minimum of 30 minutes.
Colon cancer is slow-growing cancer, and it may take years to grow. In its initial stages, it does not produce any symptoms. Additionally, the symptoms people might experience would be abdominal discomfort which they might ignore. Hence, colon cancer may be left recognized. This cancer can be prevented and treated if diagnosed at an early stage with prompt treatment. Therefore, not a single symptom related to the abdomen should be neglected especially if someone has a family history of colon cancer.
Colon cancer initially begins as a polyp inside the walls of the colon and rectum. Longstanding polyps, over time, get converted to colon cancer. It is due to certain risk factors like old age, smoking, obesity, sedentary lifestyle, male sex, high intake of fats, red meat, alcohol, processed meat, low dietary fibers, pre-existing colon diseases like Crohn’s disease, ulcerative colitis, inflammatory bowel disease, and genetic diseases.
Colon cancer is known to affect the older age groups, especially those above 50 years of age. However, there is a recent trend of few cases involving people below the age of 50. Hence the colon cancer screening age has been reduced from 50 to 45 years.
In the initial stages, colon cancers mostly do not cause symptoms or cause mild symptoms like thin and dark stools, abdominal bloating, and pain. But in the later stages, there will be changed or irregular bowel habits, bloody stools, persistent abdominal pain, cramps, weight loss without any effort, dissatisfied bowel emptying, constipation, and diarrhea.
Symptoms of colon cancer appear in the later stages, probably once the disease has reached the second stage. Initial benign polyps do not cause symptoms, and hence they do not come to the notice of the individual. Once they become cancerous, they cause vague symptoms like progressive weight loss, abdominal pain, cramps, darker and thinner stools which seldom gain attention.
Colon cancer screening tests help detect benign polyps and early stages of colon cancer. It includes colonoscopy and stool tests. In case of abnormal bowel habits, unidentified weight loss, abnormal stool mass, and blood in stools, immediate medical help must be sought as they may be signs of colon cancer.
There are changes in stool’s appearance in colon cancer. The stool becomes narrower or thin, and ribbon-like. It also gets dark, black, and tar-like. Sometimes instead of a black stool, there may be blood present in the stool.
Colon cancer can present with abdominal pain with cramps, and these are persistent. Also, there is a sudden urge to defecate even if the bowel is empty.
Colon cancer may not cause signs and symptoms in the initial stages. In some instances, it might not cause any symptoms until it is diagnosed accidentally. But usually causes symptoms like altered and frequent bowel movements, constipation, diarrhea, abdominal pain, bloating, cramps, thin and dark stools, weakness, fatigue, and progressive unintentional weight loss.
According to the American Cancer Society, it occupies the third position in the list of common cancers affecting the United States’ people. Hence it is not an uncommon condition.
Longstanding polyps or abnormal growths in the inner wall of the colon over time become cancerous, leading to colon cancer. Hence the transformation of a polyp to colon cancer is not a sudden one. Also, the spread and growth of colon cancer are regarded to be slow.
The cancerous growth is extended and limited to the deeper layers of the colon wall and may or may not include the muscle wall in stage 1 colon cancer. They do not involve the lymph nodes.
Early detection and treatment of colon cancer give excellent life expectancy and cure rates. But treatments in the later stages of the disease after cancer has spread to distant sites and beyond the colon wall decrease the cure rate and survival rates.
A single blood test cannot reveal colon cancer. However, a complete blood count (CBC) can show altered blood parameters like reduced hemoglobin levels correlated with the symptoms. The blood-based DNA test is a recently approved blood test to diagnose colon cancer risk in individuals above 50. It tests the presence of an altered SEPT9 gene. Colonoscopy and stool tests help in colon cancer screening.
Though colon cancer belongs to the category of slow-growing cancers, if not detected and treated early, it can invade the nearby tissues and organs and spread to distant parts of the body.
Based on the cancer stage and drugs, chemotherapy for colon cancer ranges from three to six months.
Excluding or limiting animal-based foods, alcohol, tobacco, and including a high fiber diet including fruits, vegetables, and whole grains help prevent colon cancer. Actively involving in regular physical activity also reduces the risk.
Last reviewed at:
02 Mar 2023 - 6 min read
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