This is a medical question of type : susceptibility 
 Who is at risk for Colorectal Cancer? ? 
 Key Points
                    - Avoiding risk factors and increasing protective factors may help prevent cancer.    - The following risk factors increase the risk of colorectal cancer:         - Age     - Family history of colorectal cancer     - Personal history     - Inherited risk     - Alcohol     - Cigarette smoking     - Obesity        - The following protective factors decrease the risk of colorectal cancer:         - Physical activity     - Aspirin     - Combination hormone replacement therapy      - Polyp removal        - It is not clear if the following affect the risk of colorectal cancer:         - Nonsteroidal anti-inflammatory drugs (NSAIDs) other than aspirin     - Calcium     - Diet        - The following factors do not affect the risk of colorectal cancer:         - Hormone replacement therapy with estrogen only     - Statins        - Cancer prevention clinical trials are used to study ways to prevent cancer.    - New ways to prevent colorectal cancer are being studied in clinical trials.
                
                
                    Avoiding risk factors and increasing protective factors may help prevent cancer.
                    Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, being overweight, and not getting enough exercise. Increasing protective factors such as quitting smoking and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.
                
                
                    The following risk factors increase the risk of colorectal cancer:
                    Age    The risk of colorectal cancer increases after age 50. Most cases of colorectal cancer are diagnosed after age 50.       Family history of colorectal cancer    Having a parent, brother, sister, or child with colorectal cancer doubles a person's risk of colorectal cancer.       Personal history    Having a personal history of the following conditions increases the risk of colorectal cancer:             - Previous colorectal cancer.     - High-risk adenomas (colorectal polyps that are 1 centimeter or larger in size or that have cells that look abnormal under a microscope).     -  Ovarian cancer.     -  Inflammatory bowel disease (such as ulcerative colitis or Crohn disease).              Inherited risk    The risk of colorectal cancer is increased when certain gene changes linked to familial adenomatous polyposis (FAP) or hereditary nonpolyposis colon cancer (HNPCC or Lynch Syndrome) are inherited.       Alcohol    Drinking 3 or more alcoholic beverages per day increases the risk of colorectal cancer. Drinking alcohol is also linked to the risk of forming large colorectal adenomas (benign tumors).       Cigarette smoking    Cigarette smoking is linked to an increased risk of colorectal cancer and death from colorectal cancer.    Smoking cigarettes is also linked to an increased risk of forming colorectal adenomas. Cigarette smokers who have had surgery to remove colorectal adenomas are at an increased risk for the adenomas to recur (come back).       Obesity     Obesity is linked to an increased risk of colorectal cancer and death from colorectal cancer.
                
                
                    It is not clear if the following affect the risk of colorectal cancer:
                    Nonsteroidal anti-inflammatory drugs (NSAIDs) other than aspirin    It is not known if the use of nonsteroidal anti-inflammatory drugs or NSAIDs (such as sulindac, celecoxib, naproxen, and ibuprofen) lowers the risk of colorectal cancer.     Studies have shown that taking the nonsteroidal anti-inflammatory drug celecoxib reduces the risk of colorectal adenomas (benign tumors) coming back after they have been removed. It is not clear if this results in a lower risk of colorectal cancer.     Taking sulindac or celecoxib has been shown to reduce the number and size of polyps that form in the colon and rectum of people with familial adenomatous polyposis (FAP). It is not clear if this results in a lower risk of colorectal cancer.    The possible harms of NSAIDs include:            -  Kidney problems.     - Bleeding in the stomach, intestines, or brain.     - Heart problems such as heart attack and congestive heart failure.              Calcium    It is not known if taking calcium supplements lowers the risk of colorectal cancer.        Diet    It is not known if a diet low in fat and meat and high in fiber, fruits, and vegetables lowers the risk of colorectal cancer.     Some studies have shown that a diet high in fat, proteins, calories, and meat increases the risk of colorectal cancer, but other studies have not.
                
                
                    The following factors do not affect the risk of colorectal cancer:
                    Hormone replacement therapy with estrogen only    Hormone replacement therapy with estrogen only does not lower the risk of having invasive colorectal cancer or the risk of dying from colorectal cancer.       Statins    Studies have shown that taking statins (drugs that lower cholesterol) does not increase or decrease the risk of colorectal cancer.