Colorectal (Colon) Cancer Quiz: Test Your Medical IQ

Colon cancer occurs when cells in the colon start to grow abnormally. There are a number of factors that increase a person's risk for developing colon cancer including:

• Age: More than 90% of cases occur in people 50 years and older
• Inflammatory bowel disease such as Crohn's disease or ulcerative colitis
• A history of colorectal cancer or colorectal polyps
• Genetic conditions including familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (Lynch syndrome)
• Lifestyle factors: sedentary lifestyle, diets low in fiber and high in fat, diets low in fruits and vegetables and high in processed meats, being overweight or obese, and alcohol and tobacco use

Colon cancer starts in the colon, and most of the time it grow slowly over many years. Most of colon cancers start as a growth on the inner lining of the colon or rectum called a polyp. Early polyp removal may prevent it from turning into cancer.

Early on, colon cancer may not cause any symptoms. When symptoms of colon cancer do occur they may include:

• Changes in bowel habits (diarrhea or constipation)
• Feeling as if you need to have a bowel movement even after you just had one
• Rectal bleeding
• Blood in the stool
• Abdominal cramping or pain
• Weakness
• Fatigue
• Weight loss
• Low red blood cell count (anemia)

After taking a medical history and performing a physical exam, some tests your doctor might order to help diagnose colon cancer include:

• Fecal occult blood test (FOBT) or fecal immunochemical test (FIT) to test for blood in the stool
• Blood tests: complete blood count (CBC), liver enzymes, tumor markers
• Diagnostic colonoscopy
• Biopsy: Lab tests of biopsy sample may include gene tests, MSI and MMR testing
• Imaging: X-ray, CT scan, ultrasound, MRI, PET scan, angiography

Colon cancer treatment usually involves surgery, sometimes chemotherapy, but very rarely radiation.

Other treatments that may be used include radiofrequency ablation in which electrodes are used to kill cancer cells, cryosurgery (cryotherapy) freezes cancer cells, targeted therapy uses drugs and other substances to target and kill the specific cancer cells while leaving healthy cells intact, and immunotherapy that uses the patient's own immune system to fight the cancer.

In primary colon cancer, the cancer is localized to the colon. In advanced stages of colon cancer, the cancer spreads (metastasizes) to distant organs, most commonly the liver, lungs, lymph nodes, and peritoneum.

Long-term consumption of red meat or processed meats has been linked to an increased risk of colon and rectal cancers. Alcohol consumption is also associated with a higher risk of developing colon cancer.

In addition, obesity is a risk factor for colon cancer, particularly when weight is gained between early adulthood and midlife.

There are numerous factors that are associated with a decreased risk of developing colon cancer, including:

• Regular exercise
• Eating plenty of fruits and vegetables
• Diets high in fiber
• Adequate intake of folic acid, vitamin B6, calcium, vitamin D, and magnesium
• Garlic consumption
• Omega 3 fatty acids (such as in fish oil)
• Coffee consumption

Survival rates for cancers are often expressed as a "5-year relative survival rate" that refers to how likely people with a certain cancer are to be alive in 5 years after being diagnosed versus people who don't have that cancer.

Survival rates for colon cancer depend on whether the cancer has spread (metastasized). The earlier the cancer is diagnosed, the better the prognosis. The 5-year survival rate for colon cancer that is localized to the colon is 90%. This means 90% of people diagnosed at this stage will be alive in 5 years. The 5-year survival rate for regional colon cancer that has spread outside the colon or rectum to nearby structures or lymph nodes is 71%. The 5-year survival rate for distant colon cancer that has spread to distant parts of the body such as the liver, lungs, or distant lymph nodes is 14%.