Colorectal cancer is a malignancy that develops in the lining of the colon and rectum, the terminal portion of the large intestine. Most of the time, the cancer begins in the colorectal cells of polyps located in the lining of the large intestine. Over time, the tumor can extend into the peritoneum and lymph nodes. In this case, the treatment becomes more difficult, and the survival chance decreases.
The main role of the colon is to ensure the absorption of water and nutrients from undigested food coming from the stomach. The rectumis responsible for the storage of feces (faeces) awaiting defecation. You have colorectal cancer when certain normal cells of the large intestine multiply abnormally to form malignant growths called glandular carcinoma or adenocarcinoma.
Colorectal Cancer Statistics
Colorectal cancer is very common in Western countries. It is the third most common cancer in men and second among women, but the second most common cause of cancer death when both sexes are combined. Worldwide, more than 940,000 new cases of colorectal cancer occur each year, causing nearly 655,000 deaths. In the United States alone, it is estimated that 146,970 men and women (75,590 men and 71,380 women) were diagnosed with colorectal cancer in 2009, and around 49,920 people (25,240 men and 24,680 women) died of it.
In 2002-2006, the highest incidence rate of colorectal cancer was registered among black people. According to the National Cancer Institute (NCI), incidence rates by race from 17 SEER geographic areas were:
- Black – 69.3 per 100,000 men – 42.1 per 100,000 women
- White – 56.9 per 100,000 men – 42.1 per 100,000 women
- Asian/Pacific Islander – 46.9 per 100,000 – 34.6 per 100,000 women
- Hispanic – 46.3 per 100,000 men – 32.2 per 100,000 women
- American Indian/Alaska Native – 43.1 per 100,000 men – 41.2 per 100,000 women
Colorectal Cancer Causes
Intestinal polyps are benign growths that develop on the lining of the colon or rectum. They may have a flat shape (sessile polyps) or have stalks or peduncles (pedunculated polyps). Most often, intestinal polyps are benign. Over time some polyps may undergo certain genetic changes and become cancerous. It is estimated that each new polyp has a risk of more than 2% to become cancerous in the first five years, and about 24% after twenty years. Hence, it is important to have regular check-ups for early detection of intestinal polyps before they turn into cancer.
Colorectal Cancer Risk Factors
There is an estimated 5.3% risk for developing colorectal cancer. Three persons out of fifty seven will have colorectal cancer in their lifetime. Many factors seem to contribute to the occurrence of the disease:
- Geography – The incidence of colorectal cancer is higher in industrialized countries.
- Age – Almost 90% of colorectal cancer occur among people over 50 years old.
- Sex – Although the disease affects both men and women, the frequency of colorectal cancer is slightly higher among men.
- Intestinal diseases – Some inflammatory bowel disorders such as Crohn’s disease (also called granulomatous colitis or regional enteritis) and ulcerative colitis increase the risk of developing colon cancer.
- Diabetes – Many studies have shown that colorectal cancer is more common among Type 2 diabetics than people who are not diabetic.
- Diet – If you want to decrease your chances of colorectal cancer, it is necessary to eat lots of fruits and vegetables. In addition, you need to reduce or completely eliminate red meat, grilled meats, trans fats, and saturated fats in your diet.
- Obesity – It is believed that obesity may play a role in the development of all types of cancers including esophageal cancer, colon cancer, breast cancer, endometrial cancer, and kidney cancer.
- Smoking – Cigarette smoke (including second hand) and chewing tobacco are major causative factors for many types of cancers. Your risk is higher if you start smoking at a young age.
- Personal or family history of colorectal cancer – If you or your family members have a history of colorectal cancer or polyps, your chance of developing the disease is higher than people who do not.
- Genetics – Studies have shown that some victims of colorectal cancer can contract the disease due to hereditary predisposition. However, this is rare; over 75% of cases of colorectal cancer have nothing to do with familial predisposition. The two most common forms of colorectal cancer that are related to genetic factors are hereditary nonpolyposis colorectal cancer (also called HNPCC or Lynch syndrome), which accounts for approximately 5% of colorectal cancers; and familial adenomatous polyposis (FAP), which involve about 1% of all colorectal cancer cases.
- Alcohol – Researchers have shown a connection between heavy alcohol consumption and cancers of the digestive tract, colon cancer, rectal cancer, esophageal cancer, laryngeal cancer, liver cancer, oral cancer, pharyngeal cancer, and even breast cancer. Moderate or occasional alcohol consumption presents no risk.
- Physical inactivity – In addition to cardiovascular disease and obesity, physical inactivity is one of the leading factors for the formation of cancerous cells. Regular physical activity improves your fitness and reduces the risk of a variety of diseases including colorectal cancer.
Colorectal Cancer Symptoms
Colorectal cancer can take several years before producing symptoms. The tumor rises asymptomatically from polyps in the lining of the large intestine without impairing your normal life; this does not prevent it from progressively damaging the colorectal tissues. When symptoms finally occur, the disease is often advanced and therefore more difficult to be treated.
In general, if you have colorectal cancer, you will experience at least one of these symptoms:
- anemia associated with fatigue
- blood in the stool
- unexplained weight loss
- constant urge to defecate
- feeling that your bowel does not completely empty
- permanent discomfort characterized by stomach cramps, gas or pain
- persistent change in bowel movements characterized by alternation between constipation and diarrhea
However, the presence of blood in your stool does not automatically mean you have bowel cancer. Certain conditions such as hemorrhoids or anal fissure can cause rectal bleeding (hematochezia). In addition, foods such as beets and red licorice can make your stools appear reddish.
Colorectal Cancer Complications
Complication of colorectal cancer may lead to gastrointestinal perforation associated with peritonitis. In addition, without effective treatment, colorectal cancer can spread into nearby lymph nodes, then to the liver, and other distant parts of the body to form metastases. Even after a successful treatment, the cancer can return in the colon. With metastases or recurrence, your survival chance is very low.
Colorectal Cancer Diagnosis
If you experience symptoms similar to those of colorectal cancer (see colorectal cancer symptoms), it is important to see your doctor as soon as possible. Colorectal cancer can be cured in 9 out of 10 cases when it is diagnosed early.
Physical exam – To start the diagnosis, your doctor will ask you questions about your medical history and the symptoms you experience. It is important that you detail all the symptoms and times they occur. Tell your doctor all recent changes happening in your digestive system. If the examination reveals a suspicion of colorectal cancer, you will be recommended to do a stool test.
Stool test – Unlike many other cancers, colorectal cancer can be detected early by less complicated examinations. Although simple, the stool test can help your doctor detect presence of blood in your stool. In fact, even without signs of colorectal cancer, this test can also be performed every two years as a means of screening for men and women aged 50-74 years. In case of a positive result, other tests such as rectal examination, colonoscopy, sigmoidoscopy, barium enema, ultrasound, and a CT scan will be performed to confirm the presence of the cancer in your intestine.
Digital rectal examination (DRE) – During a DRE, your doctor inserts a gloved finger into your rectal cavity searching for abnormalities; the test sometimes helps to identify a tumor in the rectum. Digital rectal exam is painless; however, some patients find it uncomfortable. A digital rectal examination cannot confirm the existence of colorectal cancer; other medical techniques such as colonoscopy, barium enema, and sigmoidoscopy will be performed.
Sigmoidoscopy – This invasive medical procedure allows your physician to examine the lining of your rectum and lower colon, using a sigmoidoscope – a hollow tube with a camera on the end. During the procedure, your health care provider inserts the sigmoidoscope through the rectum into the terminal section of the large intestine (sigmoid colon) to visualize and analyze it. In case growths (polyps) are found, samples will be removed to be examined under a microscope to look for cancer cells (biopsy).
Barium enema – This radiological examination allows your doctor to visualize your lower gastrointestinal (GI) segment and confirm the presence of polyps after filling the colon with a contrast material containing barium. During the procedure, the specialist injects the barium into your colon through a small tube placed in your anus. The barium travels throughout the colon, lining its walls in order to make them clearly visible on the X-ray picture. This is a quick and painless test; however, it is less and less performed since the generalization of colonoscopy.
Colonoscopy – This technique allows the visualization of the inside of the colon in its entire length using a flexible fiber optic. During the exam, your physician inserts through your rectum a flexible tube with a light called an endoscope. Unlike the barium enema, a colonoscopy allows your doctor to perform a biopsy of the tumor and remove polyps.
Other tests – Other tests such as ultrasounds and computed tomography (CT) are used in the diagnosis of colorectal cancer. These techniques allow your doctor to determine the stage of the cancer, and detect if it has spread to other organs (metastatic colorectal cancer) such as the liver.
Colorectal Cancer Stages
Determining the stage of the cancer is a very important step; it helps your oncologist to determine the type of treatment to use to better fight the disease. In addition, the cancer stage at the diagnosis plays a major role in your survival chances. In general, colorectal cancer includes the following stages:
- carcinoma in situ – Also known as stage 0, carcinoma in situ indicates the genesis of the cancer; it is still in the inner layer of the colon or rectum.
- Stage I – At stage I, the tumor has affected the mucosa of the colon or rectum, but has not yet spread beyond the colorectal wall.
- Stage II – The tumor has spread from the colorectal mucous into the wall of the colon or rectum without reaching the nearby lymph nodes.
- Stage III – A stage 3 colorectal cancer has affected the inner layer of the colorectal tissue, colorectal wall and the nearby lymph nodes; however, the tumor has not affected distant parts of the body.
- Stage IV – In this last stage, the cancer has spread to other organs of your body, such as the liver, lungs, or ovary.
- Recurrent – A cancer that has returned after treatment is considered a recurrent cancer. In general, recurrent colorectal cancers are more difficult to be treated; your survival chance is lower. To prevent recurrent cancer, after treatment, it is important that you respect your doctor’s appointments, adopt a healthy lifestyle, and consume a healthy diet.
Colorectal Cancer Treatment
The treatment of colorectal cancer varies depending on the stage (or size) and location of the tumor. In addition, your oncologist will consider your age and general health. Today, there are several therapeutic approaches to combat colorectal cancer: surgery, chemotherapy, and radiotherapy. However, when it comes to colorectal cancer, surgery is the most effective therapy.
Surgery remains the essential treatment for colorectal cancers. It consists of the removal of the bowel segment affected by the disease, the lymph nodes, and a small portion of healthy tissue surrounding the cancer. After the removal, the ends of the two healthy bowels will be joined together.
Colostomy – The type of surgery performed depends on the size and location of the tumor. In most cases, however, your surgeon will perform a colostomy. If the tumor is less aggressive, the colostomy will be temporary; however, in advanced rectal colorectal cancers or those located close to the anal sphincter, the colostomy is sometimes permanent. Depending on the localization and the size of the tumor, removal of the anus can be inevitable.
If the cancer has spread to other organs or the lymph nodes, chemotherapy combined with radiotherapy will be necessary to increase the chance of survival and reduce the risk of recurrence.
Chemotherapy is a systematic treatment that affects your entire organism. The drugs travel in all parts of your body to destroy cancer cells or prevent them from multiplying. These drugs can be taken by injection, infusion, or tablet form. Unlike surgery chemotherapy can be performed to treat advanced colorectal cancer associated with metastases in the liver, lungs, etc. Chemotherapy is often associated with radiotherapy.
Chemotherapy side effects may include:
- hair loss
- low blood cells count
Radiotherapy is the use of high-energy radiation ( energy X-rays or gamma rays) to destroy cancer cells. During the procedure, your physician delivers precise doses of radiation in the area being treated, measured according to the volume of the tumor. Unlike chemotherapy, most surrounding healthy tissues are not affected by the therapy. Radiation therapy may be performed before or after the surgery; however, in the treatment of colorectal cancer, it is often performed before the surgery to reduce the size of the tumor to make the surgical intervention easier and more effective.
Side effects of radiation therapy vary from person to another. The most common discomforts you may experience after a colorectal cancer radiation therapy include:
- redness of the treated area
- urgent need to urinate
- burning sensation during urination
- erectile dysfunction (temporary)
After the treatment your doctor will recommend regular monitoring to prevent or detect early relapse or complications. At least once a year, your oncologist will do a chest x-ray to determine the response of your body to the treatment. In addition, a liver ultrasound and/or abdominal CT scan can be performed every four months for two years following the treatment.
Blood tests will be also necessary to monitor your white and red blood cells. These blood tests allow your physician to detect abnormal liver function. Your oncologist may recommend a colonoscopy a few months after the treatment to visualize the lining of your intestine. If there are multiple polyps, they will be removed and a new colonoscopy will be performed in 9 to 12 months. If the new colonoscopy reveals no polyps, another colonoscopy will be performed five years later.
Colorectal Cancer Survival Rates
Colorectal cancer prognosis depends greatly on the stage of the cancer or the extent of the tumor at diagnosis. Usually, a 5-year survival rate for a colorectal cancer diagnosed at stage 1 is approximately 94%. In fact, the majority of patients who have their cancer detected early are completely cured. However, colorectal cancer is often diagnosed when the tumor has already severely damaged the colon.
According to the National Cancer Institute (NCI), the overall five year relative survival rate for 1999-2005 from 17 SEER geographic areas was 65.2%. Five-year relative survival rates by race and sex were:
- 66.3% for white men
- 65.9% for white women
- 55.5% for black men
- 56.7% for black women
Colorectal Cancer Prevention
Several methods can be used to prevent colorectal cancer.
Early detection – To find early cancerous or precancerous polyps, it is now recommended for all persons to undergo testing on a regular basis from the age of forty. The earlier the cancer is detected, the higher your chances of recovery. It is estimated that screening for colorectal cancer can reduce up to 33% of colorectal cancer deaths among people aged fifty and over.
Do not wait for the manifestation of symptoms to see your doctor; from the time you experience symptoms, the cancer is already advanced, and your healing or survival chances decrease.
Lifestyle – These steps can help you prevent colorectal cancer and other types of cancer:
- Eliminate foods that can lead to the development of colorectal cancer like red meat, grilled sausage, smoked ham, salami and sausages. If you cannot stop consuming them, eat them rarely and moderately.
- Quit smoking. Smoking is the source of a variety of diseases including colorectal cancer.
- Exercise at least 3 times a week.
- Consume alcohol moderately; heavy drinking increases your risk of developing colorectal cancer.
- Take vitamin D supplements in autumn and winter. If you are elderly or rarely exposed to the sun, you can take vitamin D during all seasons.
- Eat plenty of fruits, vegetables and grains; these foods are rich in nutrients and antioxidants that keep not only your digestive tract healthy but also your whole body. It is shown in many studies that fruits and vegetables when consumed regularly and in great quantity, have beneficial effects in preventing and fighting against almost all types of cancer.