Colorectal Cancer FAQs

Top 10 Colorectal Cancer Questions Answered

1. Is colorectal cancer common?

   Yes, colorectal cancer (CRC) is a common and deadly disease. In the United States, CRC is the third most diagnosed cancer and the second leading cause of cancer death. Approximately 148,610 new cases of CRC are diagnosed each year, of which 106,680 are colon (the remainder are rectal cancers). 
   
   Globally, the incidence of CRC is ten-fold, with the highest incidence rates in North America, Australia and northern and western Europe.

2. What are the risk factors?

   Environmental and genetic factors can increase the likelihood of developing colorectal cancer. The following elevates an individual's risk of developing CRC:
   Specific genetic disorders such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer.
   •    Personal history of sporadic cancers or adenomatous polyps, which increases the risk of large bowel cancer.
   •    Family history of colorectal cancer in a close relative (parent, sibling, or child). This increases an individual's risk by 1.7 percent. The risk is further increased if two first-degree relatives have colon cancer or if the index case is diagnosed before 55 years of age.
   •    A family history of colonic adenoma, which appears to carry the same significance as a family history of CRC.
   •    Inflammatory bowel disease (IBD), such as ulcerative colitis and Crohn's colitis
   •    Diabetes mellitus, insulin resistance, and chronic insulin therapy.
   •    Alcohol consumption increases risk modestly, particularly in those who consume alcohol in excess of 45 grams per day.
   •    Cigarette smoking
   •    Ureterocolonic anastomosis
   •    Prior pelvic irradiation
   •    Consumption of red or processed meats   

3. Can colorectal cancer be prevented? If so, how?

   Screenings, like colonoscopies can detect CRC. Also, certain practices have been identified as protecting the body against CRC, including:
   •    Diet high in fruits and vegetables, and low in red meat, animal fat and/or cholesterol
   •    Folic acid, vitamin B6 and calcium
   •    Regular physical activity and maintenance of normal body weight
   •    Smoking cessation
   •    Regular use of aspirin or nonsteroidal anti-inflammatory drugs
   •    Hormone replacement therapy in postmenopausal women (although these drugs are not routinely recommended for chemoprevention of colon cancer due to the associated long-term risks).
   •    HMG-CoA reductase inhibitors (statins), although data is conflicting.

4. Are there symptoms of colorectal cancer?

   It’s important to note that there may be NO symptoms at all. However, if symptoms do develop, they vary depending on the location of the cancer within the colon or rectum.
   
   Cancers arising on the left side of the colon generally cause:
   •    Rectal bleeding
   •    Constipation
   •    Abdominal pain
   •    Obstructive symptoms
   
   Cancers arising on the right side of the colon generally cause:
   •    Vague abdominal aching
   •    Weakness
   •    Weight loss
   •    Anemia from chronic blood loss

5. Does colorectal cancer affect demographics differently?  

   Those assigned male at birth tend to get colorectal cancer at an earlier age than biological women. However, those assigned female at birth live longer - so they “catch up” with biological men.  This means the number of cases are equal regardless of gender.
   
   In the United States, incidences of colon cancer declined by three percent between 1998 and 2000. During this period, the average annual incidence rates per 100,000 population were 64.2 from men and 46.7 for biological women. Despite such data, during the same time period, the incidence rates for right-sided cancer increased, particularly in biological women. In addition, while tobacco and alcohol increase the risk of colorectal cancer, biological women who smoke are at a higher risk. 
   
   Among biological women, CRC screening rates are still relatively low (30-40%) and are comparable to mammography rates 20 years ago. 
   
   Black Americans are at a much higher risk for colon cancer than other races. They have a significantly lower age at diagnosis and experience a larger number of polyps and cancer in the proximal colon. 
   
   In 2019, an estimated 20,000 Black Americans were diagnosed with colorectal cancer with more than 7,000 deaths. Black Americans have the highest rates of colorectal cancer amongst any ethnic group in the United States.

6. Does age play a role in incidences of colorectal cancer?

   Age is a major risk factor for sporadic CRC. The lifetime incidence of CRC in patients at average risk is about 5 percent, with 90 percent of cases occurring after the age of 50. 
   
   However, The American Cancer Society’s colonoscopy screening guidelines recommend people with an average risk of colorectal cancer begin regular screenings at age 45, whether or not they are experiencing symptoms.

7. Is colorectal cancer always fatal? What are the mortality rates?

   Most colon and rectal cancers originate from benign wart-like growths on the inner lining of the colon or rectum called polyps. Not all polyps have the potential to transform into cancer. Those that do are called “adenomas.” 
   
   It takes more than 10 years, in most cases, for an adenoma to develop into cancer. Screening, like a colonoscopy, identifies cancers earlier, before symptoms develop. This dramatically improves the chance of survival. 
   
   Identifying and removing polyps before they become cancerous - prevents the development of colorectal cancer. The pathologic stage at diagnosis remains the best indicator of long-term prognosis. The most important characteristics are the presence of distant metastases, local tumor extent, nodal positivity, and residual disease. 
   
   Five-year survival rates vary from 93 percent for stage I to 8 percent for stage IV colon cancer. Five-year survival rates for rectal cancer tend to be somewhat lower.

8. What colorectal screenings are available?

   The American College of Gastroenterology considers colonoscopy the preferred screening test, but the following tests are available:
   •    Annual fecal occult blood test: If this comes back positive, a colonoscopy should be done.
   •    Double contrast barium enema: It is less effective than a colonoscopy and due to its limitations, not widely used for CRC screening.
   •    Sigmoidoscopy for examination of the lower colon and rectum. If an adenoma is found, a colonoscopy should be performed. Sigmoidoscopy does not examine the entire colon and so is less reliable. Sedation is usually not used. It is performed every five years, often in conjunction with an annual fecal occult blood test.
   •    Colonoscopy: The entire colon and rectum is examined, and polyps can be removed during the procedure, which is usually done under sedation.
   •    Computed tomographic (CT) colonography and magnetic resonance (MR) colonography: Sometimes called "virtual colonoscopy." Both are new methods and not yet established as reliable screening methods. If polyps are found, a colonoscopy with polypectomy should be performed.

9. How often should you get a colonoscopy?

   Screenings can detect CRC when it can be treated. For individuals at normal risk, screening tests should begin at age 45. The preferred approach is a screening colonoscopy conducted every 10 years. 
   
   In addition, consider the following recommendations for screening:
   •    Physician experts with the American College of Gastroenterology issued new recommendations that CRC screening in Black Americans begin at an earlier age.
   •    Colonoscopic surveillance needs to be performed at more frequent intervals for individuals at high risk for colon cancer (for instance, those with a personal history of CRC or adenomatous polyps, family history of CRC, HNPCC, FAP or IBD).
   •    An alternate strategy consists of annual stool test for blood and a flexible sigmoidoscopic exam every three to five years.

10. Does a colorectal screening hurt?

    Colonoscopies are done under conscious sedation using a combination of painkillers and sedatives given intravenously. Patients are usually comfortable during and after the colonoscopy.

    
    The day before the procedure, the patients need to take a bowel preparation, which is available in different forms and well-tolerated.
    
    Complications including perforation and major bleeding are unusual, about one to two per 1,000 procedures.