Colorectal Cancer, also known as bowel cancer, colon cancer, or rectal cancer, is the type of cancer that affects the colon and the rectum. It’s called colon or rectal cancer depending on the origin, though they are often grouped because of the common symptoms and effects. Colorectal cancer usually emerges in the innermost layer and can grow through all of the layers. The cancer cells can also develop into blood vessels and travel to distant body parts from there. The stage of colorectal cancer depends on how deeply it grows into the wall and its development outside the colon or rectum.
As approximated by the American Cancer Society, about 1 in 21 men, and 1 in 23 women will have colorectal cancer in the United States during their lifetime. It is also the second-leading cause of death in women and the third for men. Although the death rates have significantly reduced due to advancements in technology and treatments.
Colorectal cancer can be present long before the symptoms develop as the person may not experience any of these symptoms in the early stages. Symptoms may vary depending on the size and location of the tumor.
Colorectal cancer symptoms include:
- Changes in bowel movement frequency and habits
- Fatigue or tiredness
- Unexplained iron deficiency
- Blood from rectum
- Abdominal discomforts, like cramps or gas
- Rectal pain, which generally refers to a bulky tumor
- Feeling that bowel doesn’t empty properly
- Irritable bowel syndrome
- Unexplained nausea or vomiting
Colorectal Cancer Risk factors and prevention:
Having a risk factor, or many of them does not necessarily mean that the person will develop the tumor. It can still occur without any risk factors. The factors that increase the risk of developing colorectal cancer are:
- Older age: A majority of people diagnosed with colon cancer are above the age of 50, though the numbers are now increasing in the younger age group as well.
- Personal or Family history: If the person had colon cancer at any time before, there’s a higher risk of developing cancer in the future. Having a blood relative with colon cancer also increases the risk of having the disease.
- Smoking and alcohol: People who regularly smoke and drink have an increased risk of developing cancer.
- Obesity: Obese people usually have a higher risk of developing and dying from colon cancer when compared with the people having a healthy weight.
- Inactive lifestyle: People who stay inactive are more likely to develop colon cancer. Keeping an active lifestyle and exercising decreases the risk of suffering from the disease.
Many factors that increase the risk of developing cancer are beyond control, such as aging and family or personal history. Other factors can be avoided by making changes in the lifestyle. Avoiding risk factors like smoking, drinking, unhealthy eating, and obesity can decrease the chances of cancer. Consulting a doctor regularly can be a good idea as taking medication to treat a precancerous condition or to prevent it from starting can avoid the risk of developing cancer.
Diagnosis and Treatment:
Multiple screening and diagnosis methods can be used to detect colon cancer during the early stages when the chances of curing it are much better. With proper screening, the polyps can be found and removed before they can turn into cancer.
Screening tests for colorectal cancer are divided into two groups:
- Stool-based tests, which checks the stool for signs of cancer
- Visual (structural) exams, which is done with a scope or an x-ray to look for any abnormalities in the structure of the colon and rectum.
1) Stool-based tests
These tests include looking at the stool (feces) for any signs of colorectal cancer. They are usually done at home and still require a colonoscopy afterward to make sure about cancer.
Types of stool-based tests are:
- Fecal immunochemical test (FIT): This test is performed to look for hidden blood in the stool. During cancer, the blood vessels often get damaged due to the passage of the stool and bleed into the colon or rectum. If the test results are positive i.e. hidden blood is detected, a colonoscopy is done to diagnose cancer accurately. A colonoscopy is needed because the blood can also have other causes, such as ulcers and hemorrhoids.
- Guaiac-based fecal occult blood test (gFOBT): This test also detects hidden blood just like in FIT, but using a different method through a chemical reaction. In gFOBT also, a colonoscopy is required because the blood is not enough to prove the presence of cancer cells in the rectum or colon.
- Stool DNA test: Colorectal cells have DNA mutations which are often found in stool. This test looks for abnormal DNA from the cancer cells. Cologuard is the test which is performed to check for both DNA changes and blood in the stool.
2) Virtual (Structural) Tests:
- Colonoscopy: In a colonoscopy, a flexible tube about the width of a finger with a light and a small video camera is used. The colonoscope is put through the anus into the rectum and colon. Special instruments can also be passed through it to biopsy or remove any areas like polyps if needed.
- CT Colonography: This involves a Computed Tomography(CT) scan of the rectum and colon. A CT scan is different from an x-ray as it takes many pictures while rotating around you, unlike an x-ray which takes only one image. This test can be done very quickly without any sedation. If anything suspicious detects during this test, a colonoscopy will still be needed to remove that part or to diagnose it further.
- Flexible sigmoidoscopy: Sigmoidoscope is flexible and lighted tube about the width of a finger with a small video camera on one end. It is put through the anus into the lower part of the colon. The images are displayed on the screen. It is different from a colonoscopy as it only examines the lower part of the colon.
The treatment options depend on various factors concerning cancer, such as the size, location, and the stage of cancer.
The options available for treating colon cancer are:
- Radiation therapy: Under this process, high-energy rays (such as x-rays) or particles to destroy the cancer cells. This method is mainly used for rectal cancer, rather than colon cancer. Sometimes, radiation therapy is used along with chemotherapy, which makes the treatment a lot more effective. When these two methods are used together, it is known as chemoradiation or chemoradiotherapy.
- Surgery: Surgery is the most common treatment for colorectal cancer. As a part of the surgery, the tumor and the nearby lymph nodes are removed to reduce the chances of cancer spreading to other parts of the body. If the cancer is diagnosed in the early stage, surgery can successfully remove the tumor, or at least ease the symptoms that follow cancer.
- Chemotherapy: It involves using medicines to destroy the cancer cells. It can help in shrinking the tumor and is mainly used for colon cancer treatment. It includes targeted therapy which targets only the cancer-causing elements, which is considered better than other therapies due to low side effects. The drugs commonly used for colorectal cancer treatment include bevacizumab (Avastin) and ramucirumab (Cyramza).