This article includes important information about colorectal cancer, including its prevalence, spread, diagnosis, treatment, and preventive measures.
Colorectal cancer (CRC) is a type of malignant tumour that occurs in the inner wall of the colon and rectum. In most cases, colorectal cancer develops from colon polyps. Early colorectal cancer and colon polyps do not show any cancer-specific symptoms. Therefore, early detection and regular colorectal cancer are important for its early management.
Colorectal cancer is a serious disorder that refers to the abnormal division of colorectal cells, resulting in increased growth of both colon and rectum.
Globally, it was estimated to have 18.1 million new cancer cases, and 9.6 million deaths caused by cancer in the year 2018 . CRC is the second leading cancer-related mortality and the third most commonest diagnosed cancer [7,8]. It is estimated that among half of the new cases, deaths and 5-year prevalent cases were found in Asia.
Due to this, many Asian countries, including Singapore, Japan, and South Korea, have introduced screening programs to limit the increasing percentage of CRC.
The five-year prevalent study of different Asian countries showed the following results :
One Malaysian study found that the Chinese had the highest age-standardized occurrence (27.35/100,000) and age-standardized mortality rate (11.85/100,000) . This, therefore, concluded that Chinese people have a higher incidence rate of CRC than Indians and Malays.
The age-adjusted CRC prevalence among Asian people was conducted in California. It was discovered that foreign-born Japanese have three times higher rate (74.6/100,000) than the rest of the foreign-born South Asians 
The digestive cavity of the human body is highly advanced. When the food is ingested, it is absorbed by the intestines. The intestines are of two types; small and large intestine. The Colon and rectum are a part of the large intestine.
The colon is a hollow U-shaped 5 feet tube consisting of muscles. It connects the stomach with the rectum and helps with food and water absorption. It also helps store waste products until they are egested from the body.
It comprises the following parts:
It is the last part of the colon (6 inches) and the second last of the digestive system. It consists of sphincter muscles that help with excretion. The sphincter allows the rectum to prevent accidental elimination of faeces.
The colon receives food and water from the small intestine. The water and salts are firstly absorbed while the rest of the food travels to the rectum. The undigested food is stored in the rectum until defecation. The sphincter is a ring-shaped muscle that prevents the undigested food from accidentally coming out of the anus.
Colorectal cancer is a serious disorder in which abnormal division of colorectal cells occurs, resulting in increased growth of both colon and rectum. It first begins as a slight outgrowth on the inner surface of the colon and rectum, called polyps.
In some cases, these polyps become cancerous. Following are some of the common types of polyps:
1. Adenomatous Polyps: These are precancerous polyps and are also called “adenomas.” They are found as villous, tubular, and tubulovillous.
2. Hyperplastic Polyps: Colorectal cancer screening with a colonoscopy may be required more frequently in some persons with big hyperplastic polyps as they are more common.
3. Sessile Serrated Polyps (SSP): These are often treated similarly as adenomatous as they have a higher risk of causing colorectal cancer.
The alarming point for CRC is when the polyp is greatly enlarged (approximately more than 1 cm).
If a polyp becomes cancerous, it grows deeper within the walls of the colon and rectum. Since the walls of the colon are made of several years, it spreads slowly. It affects the inner layer (the mucosa) and extends outwards towards other layers.
Cancer then travels into the blood and lymph vessels and lymph nodes, and other body parts. If CRC remains undiagnosed, it starts affecting other body parts, which negatively impacts the patient in a number of ways .
The American Chemical Society (ACS) recommends regular screening for CRC from the age of 45. While most people with good health start regular screening from age 75 through stool tests and other physical colon and rectum exams.
People are considered to be at moderate risk for screening tests if they don’t have:
There are many risk factors associated with the incidence of CRC; as follows:
Following assessments are performed for the diagnosis of colorectal cancer:
These are less invasive and help to determine any abnormality in the faeces. The following diagnostic tests are used for stool analysis:
Visual examination is a thorough test and helps in locating any abnormality by structural examination of the colon and rectum. It is done by colonoscopy (after every ten years), CT colonography (after every five years), and flexible sigmoidoscopy (after every five years).
The increased colorectal cases in Asia are due to many factors like population, lack of awareness, diet, and lack of screening. Colorectal cancer, if it remains undiagnosed, can be fatal. Therefore, if the person has a family of polyps or CRC, they should get tested every year as early diagnosis can ease the procedure to a great extent.
Consultant General Surgeon
KMI-Taman Desa Medical Centre
Clinic: +603-7982 6500 (Ext: 25192520)