Colon Cancer: Epidemiology and Risk Factors


Colon cancer ranks among the top most cancers all around the globe. There are several factors that contribute to its incidence, some of which are discussed in detail in the context given below. Unfortunately, all of the mentioned factors are almost inevitable.

Epidemiology 

Age 

Colon cancer is one of those types of cancers that are more common in older individuals. The risk increases as people get into the age of 40 and risk grows with each year. Although the media presentation varies from each country, the media presentation of colon cancer in the US is at 72 years.

Gender

The prevalence of colon cancer is different between males and females. At a ratio of 1.2:1, slightly more women are affected than men, while rectal cancer affects more men at a ratio of 1.7:1.

Geography

The incidence can vary in every country. However, the development of colon cancer is associated with industrial cancer i.e. United States, UK, Australia, Canada and some European countries. Fewer accounts of colon cancer have been recorded in less industrialized areas such as Asia, South America, and Africa.

Race

Regarding race, more African Americans are affected compared to Caucasians in the US. In fact, the incidence of colon cancer among African Americans has increased by 30% in the last 30 years.

Risk factors that you cannot change:

Risk factors that cannot be modified are pre-existing in the human body. These are also called non-modifiable risk factors.

Family history of Colorectal Adenoma or Colorectal Carcinoma

Family members of patients having colorectal adenoma have less established risk compared to family members of patients having colorectal carcinoma. Studies reveal that the risk of colorectal cancer among first-degree relatives of patients being diagnosed with adenomas was elevated compared to the first degree relatives of those having carcinomas. The risk is even higher to the family members if the patient is diagnosed with colorectal carcinoma at a younger age and if there are several patients among the family.

Inflammatory Bowel Disease

Inflammatory bowel disease such as Ulcerative colitis and Crohn’s disease can also increase the risk of colon cancer forming. These inflammatory disorders of the bowel, characterized by abnormal activities within its cells and tissues, are predisposing factors for colorectal cancer formation. If these diseases are not treated, the risk of colorectal cancer formation is increased by 3% within ten years, and up to 20%, when left untreated for 20 years.

Ureterosigmoidostomy 

A colon cancer patient of 30 years of age was traced to have a history of Ureterosigmoidostomy 15 years ago. Ureterosigmoidostomy is a medical treatment for bladder cancer. It is done by removing the urinary bladder and transferring the passage of ureters towards the sigmoid colon. With this procedure, the natural environment of the intestines is disturbed by the presence of the ureters. This presence can cause a risk of developing carcinoma of the colon.

Streptococcus Bovis Infective Endocarditis

It has been determined that having a history of Infective Endocarditis (inflammation of the inner tissue of the heart caused by bacteria) is another risk factor for the development of colon cancer. A study reported a close connection between tumor of the human colon and S.bovis infections. S.bovis Endocarditis is considered as an indicator for a colonoscopy because most of these S.bovis Endocarditis patients are also diagnosed with either colon carcinomas or colon polyps. Therefore it is advisable to undergo colonoscopy if you have a medical history of S.bovis Endocarditis to check for the presence of colorectal tumors. If no tumors or growths are found, regular annual check-ups must be done.

Race 

Race or ethnic background is also a risk factor for colorectal cancer. Among all races in the United States, it was revealed that African Americans have the highest incidence and mortality rate of colorectal cancer. From the rest of the world, Jews from Eastern European descent called Ashkenazi Jews are number one to have the highest risk of colorectal cancer because recent findings show that a very common gene mutation called I1307K APC that leads to colorectal cancer is found in this race.

Colorectal Polyps

Colorectal Polyposis formation is usually traced to the genetic information and is called Familial Adenomatous Polyposis FAP. A person inherits this trait from either of his parents. Individuals with FAP usually develop numerous polyps in their rectum or their colon and 1 or 2 of these polyps may develop into colorectal cancer. Patients who are found to have colorectal polyps have 3% higher risk of developing colorectal cancer compared to those who do not have. All colon cancers and rectal cancers, which start from colorectal polyps. Although most colorectal polyps are precancerous in nature if left alone, there is a very high risk of colorectal cancer development which is also dependant on the size of the polyps.


Dr. Adem Gunes
Dr. Abdullah El-Hossami