What Is Colorectal Cancer?
Colorectal cancer is one of the major malignancies in the western world. In the U.S., there are over 145,000 cases each year and the disease accounts for some 51,000 deaths. It’s the third most common cancer in both men and women. There are less incidences in African and Asian countries. While no one is 100% safe from any type of cancer, prevention, screening and early detection are crucial for the chance of having favorable outcomes.
Colorectal Cancer Explained
Colorectal cancer is a malignant tumor that grows in the cells lining the large bowel and rectum. A person can have cancer of the colon or the rectum, or both. They are often discussed together because they share the same risk factors and symptoms.
Cancer happens when the cells multiply rapidly, forming solid tumors that can either be benign or malignant. Cell division is an important process that is necessary for the body’s growth and repair. Unlike normal cells, cancer cells divide and grow uncontrollably. Colorectal cancer can develop from certain types of benign growth in the mucous membrane of the intestine, known as polyps.
Polyps are commonly found in people over the age of 50. They usually grow in the colon, but they can develop in other parts of the body like the cervix, nose, uterus and stomach. Removing these abnormal growths is one way to prevent colon cancer. New polyps can develop in about half of those who have them removed. This is why regular monitoring is advised.
What Are the Symptoms of Colorectal Cancer?
Signs and symptoms of colorectal cancer are often overlooked because there are many diseases with the same indications. Consult a doctor if you are experiencing any of these symptoms:
- Nausea or vomiting
- A change in bowel habits (prolonged diarrhea or constipation)
- Presence of blood (bright or dark red) in the stool
- Unexplained weight loss
- Abnormal tiredness
- Frequent abdominal issues (gas pains or cramps, feeling bloated)
- A feeling of incomplete bowel emptying (tenesmus)
- Stools that are narrower than usual
Causes and Risk Factors of Colorectal Cancer
The exact causes of colorectal cancer are unknown. Research suggests that a combination of factors is responsible. Anyone can get colorectal cancer, but some people are more at risk than others. The risk increases with age.
Non-preventable risk factors include:
- History of adenomatous polyps
- Chronic colon diseases (ulcerative colitis, inflammatory bowel disease or Crohn’s disease)
- Family history of colorectal cancer
Preventable risk factors include:
- Cigarette smoking
- Moderate to heavy alcohol consumption
- Excessive consumption of processed food and red meat
- Sedentary lifestyle
- Being overweight or obese
What Are the Stages of Colorectal Cancer?
Staging is an important component of cancer management. This process helps doctors determine how much cancer is in the body and whether it has spread to other organs and tissues, such as the liver, lungs, or bones.
Assessing the stage of colorectal cancer is usually established after conducting a series of imaging tests, including a diagnostic colonoscopy, magnetic resonance imaging (MRI), computed tomography (CT) scan and an ultrasound.
The TNM classification, also known as the AJCC staging system, is a globally accepted standard for staging malignancies. It describes the site of the primary tumor (T), the involvement of nearby lymph nodes (N) and the degree of metastasis or cancer spread (M).
This is known as carcinoma or intramucosal carcinoma. This is the earliest stage of cancer and has an excellent prognosis with a five-year survival rate greater than 90%. At this stage, the tumor has not crossed the inner lining of the colon or rectum.
This is when the cancer has grown beyond the innermost lining (muscularis mucosa) into the second and third layers (submucosa or muscularis propria). At this stage, it has not spread to the lymph nodes and distant organs yet.
Stage 2 is split into three parts. First, the cancer has spread into the outermost layers but has not completely penetrated the colon wall. There is no lymph node involvement and no metastasis.
The second part is when the cancer has spread through the wall of the colon or rectum but has not reached nearby tissues and organs. There is no metastasis and regional lymph node involvement.
By part three, the cancer has spread through the wall of the colon and nearby tissues and organs. There is no lymph node involvement and no metastasis yet.
Like stage 2, stage 3 is also split into three different parts. At first, the cancer has spread to the middle layers (submucosa or muscularis propria) and to one to six nearby lymph nodes or the fats near the lymph nodes. There is no distant site metastasis.
At part two, the cancer has spread to other organs and tissues and involves one to three lymph nodes. The tumor has not yet passed through the outer layers of the colon wall but has spread to four or more lymph nodes.
By part three, the cancer has grown beyond the middle tissue layers (or nearby tissues) or nearby organs. It has spread to four or more nearby lymph nodes.
This is the advanced stage of colorectal carcinoma. By now, the tumors have spread to nearby lymph nodes and other parts of the body, such as the lungs or liver.
What Are the Treatment Options for Colorectal Cancer?
The treatment options for a patient who has colorectal cancer will depend on the stage of the cancer, their age and what their body can handle. Here are the most common treatment plans.
Removing the tumor is the most common treatment for all stages of colorectal cancer. It may be performed using local excision, resection, or resection and colostomy.
These are drugs that kill cancer cells and are administered intravenously or by mouth. You may experience nausea, vomiting, hair loss and other side effects.
X-rays and other types of radiation may also be used to shrink tumors and kill cancer cells. Careful treatment planning is important, as radiation cannot distinguish between tumor cells and normal cells.
Over the years, many biological drugs have been introduced to combat advanced colorectal cancer. Biologics have different mechanisms of action; some target the cancer cells while others boost the immune system to attack cancer cells more effectively.
Here are the different treatments by stage:
- Stage 1: surgery
- Stage 2: surgery, chemotherapy or biologics, radiation
- Stage 3: surgery, chemotherapy or biologics, radiation
- Stage 4: surgery, chemotherapy, biologics radiation, or interventional radiology
How to Reduce the Risk of Colorectal Cancer
This type of cancer develops slowly. Symptoms often appear when cancer has already spread. When discovered at an early stage, most cancers have an excellent prognosis. Here’s how you can reduce your risk of colon and rectal cancer:
- Consume more fruits, vegetables and other foods that are rich in fiber
- Reduce fat in your diet
- Eat fish or poultry and reduce your intake of red meat and processed food
- Stop smoking
- Consume alcohol moderately
- Be mindful of your symptoms
- Participate in screening programs
- Exercise regularly
- Maintain a healthy body weight