A risk factor may be a contributing cause that increase your possibility to contract a disease. Different cancers have different risk factors. Some of these, like smoking, are modifiable risk factors. However, factors like the age or family history cannot be modified.
If you have one or more risk factors, this does not mean you will have that disease. In addition, having no risk factor does not protect you against that disease.
Studies identified many risk factors that increase the risk of colorectal polyp or cancer development.
MODIFIABLE RISK FACTORS FOR COLON AND RECTUM CANCER
Many lifestyle related conditions are identified as risk factors for colon and rectum cancer and most important of these are;
1. Excess weight or obesity: This situation is more significant in men, however, it is a risk factor for colorectal cancer development for both genders.
Physical activity: If you have a sedentary lifestyle, this puts you into the risk group.
Some nutrition types: Nutritional habits that are rich in red meat and processed meat products increase colorectal cancer development risk. Cooking food with very high temperatures (frying, barbecue, roasting) may increase your cancer risk due to the chemicals released by high heat; however, the extent of this increased risk is not known. On the other hand, nutrition rich in vegetables, fruits and whole grains decreases the colorectal cancer risk.
Smoking: Colorectal cancers and related deaths are more prevalent in long time smokers.
Alcohol use: Excess amount of alcohol consumption is identified as a risk factor associated with colorectal cancer development. Consumption of more than 2 glasses of alcohol for men, and 1 glass of alcohol for women increases the risk.
UNMODIFIABLE RISK FACTORS FOR COLORECTAL CANCER
Age : Colon and rectum cancer risk significantly increases after the age of 50.
Colorectal polyp or cancer history: If you were previously diagnosed with adenomatous polyp, it means you are in the risk group for colon and rectum cancer. This risk significantly increases in the presence of large or multiple polyps. If you received treatment for colorectal cancer diagnosis, the risk continues for new cancer development in the remaining regions of your intestines. This risk increases further if you were diagnosed with colon or rectum cancer in an early age.
Inflammatory bowel disease: If you have an inflammatory bowel disease like ulcerative colitis or Crohn?s Disease, this increases your risk of colorectal cancer development. Inflammatory bowel disease is the long term inflammation of the colon and generally dysplasia develops in these patients. Cells with dysplasia can turn into cancer in time. In the presence of these diseases, screening for colorectal cancer must start earlier and performed more frequently.
Colon, rectum cancer or adenomatous polyp history in the family: In case your first degree relatives have colon or rectum cancer, this means you also have a high risk. If your relative is diagnosed before the age of 45 or having more than one first degree relatives with the disease further increases your risk. Genetic predisposition, exposure to same environmental factor or all of these may be among the causes of the increased incidence of these disease within the family. Most of the patients diagnosed with colon or rectum cancer do not have such family history, however, one in every five patients there is a family member diagnosed with colorectal cancer. This is also true for adenomatous polyps. Therefore, individuals who have first degree relatives diagnosed with colon or rectum cancer or adenomatous polyps must start having routine screenings before the age of 50.
Type 2 diabetes Colorectal cancer development risk is higher in Type 2 (non-insulin-dependent) diabetes patients. In fact, both diseases have common risk factors such as excess weight and obesity. However, this high risk is present independently from common factors and treatment results in these patients are poorer.
Presence of inherited syndrome: 5-10% of patients with colon, rectum cancer development have inherited genetic disorder (mutations) that cause familial cancer syndromes. Familial adenomatous polyposis (FAP) and Lynch Syndrome (hereditary non-polyposis colorectal cancer, or HNPCC) are the most common syndromes known to be associated with colorectal cancer, however, other rarer syndromes may increase the colon and rectum cancer risk.
INHERITED COLORECTAL CANCER SYNDROMES
Familial adenomatous polyposis (FAP): FAP is caused by mutated APC gene that is inherited from parents. Approximately 1% of all colorectal cancers are caused by FAP. In the most common type of FAP, hundreds or even thousands of polyps are formed in the colon and rectum during the adolescence period. Cancer generally develops in one or more of these polyps in the 20s. If the colon is not removed for precaution, almost always colon cancer develops by the time the patient turns 40. Incidence of stomach, small intestine and other organ cancers also increase in people with FAP. In a sub-type of this disease where polyps are less than 100, colon or rectum cancer development occurs in latter ages.
Gardner syndrome is a FAP type that is accompanied by non-cancerous tumors in skin, soft tissue and bones.
Lynch Syndrome (hereditary non-polyposis colorectal caner, or HNPCC): Lynsch Syndrome is responsible for 2-4% of all colorectal cancers. It is generally caused by a hereditary disorder in MLH1 and MLH2 genes that help repair DNA damage. Colon and rectum cancers develop in patients who have Lynch syndrome, but later than those with FAP. There may be polyps in people with Lynch syndrome but they are generally a few. Colorectal cancer development risk of these patients may increase up to 80% depending on the affected gene. Simultaneous or separate endometrium cancer development risk is also significantly increased in women. In addition, there is an increased incidence of ovarian, pancreatic, renal, brain, ureter and bile duct cancers.
Turcot syndrome: In this rare inherited condition, in addition to increased colorectal cancer and adenomatous polyp development, brain tumors are also reported more frequently. Turcot syndrome has 2 types. One has genetic disorders similar to FAP and brain tumors of these patients are medulloblastomas. Other type has genetic disorders similar to Lynch syndrome and glioblastoma develops.
Peutz-Jeghers syndrome: In this rare inherited disease, skin spots are formed around mouth and sometimes hands and feet, and a different type of polyp called hamartoma is seen in the digestive system. In addition to several different cancer types, these patients are also in the risk group of colorectal cancer and tumors generally occur in early ages. Mutations of STK1 gene is the cause.
Polyposis accompanied by MUTYH If the colon is not removed in these patients, adenomatous polyps become cancerous. There is also an increased incidence of small bowel, skin, ovarian and bladder cancer in these patients. Disease is caused by MUTYH gene mutations.
Generally, all of these syndromes cause cancers to occur in earlier ages than normal. Therefore it is important to perform screenings and take necessary measures at earlier ages for these family members.