Causes of colorectal cancer - What you often ask your doctor

Posted by Master, Doctor Mai Vien Phuong - Department of Examination & Internal Medicine - Vinmec Central Park International General Hospital

Colorectal cancer is a type of cancer that occurs in the colon (large intestine) and rectum. According to the American Society of Clinical Oncology (ASCO), it is the third most commonly diagnosed cancer. Screening and early detection of colorectal cancer can improve the chances of surviving this type of cancer.

Most cases of colorectal cancer begin as a type of polyp called an adenoma. These polyps are not cancerous, but can turn cancerous.
In many cases, doctors don't know what causes polyps or what causes them to turn cancerous. However, there are genes that may increase the risk of colorectal cancer. These genes cause a small percentage of colorectal cancer but significantly increase the risk.
Hereditary conditions that increase the risk of colorectal cancer include:

People with familial adenomatous polyposis (FAP) develop hundreds to thousands of polyps in their colon and rectum. Polyps can start growing as early as someone's teen years and will become cancerous if not removed. The number of polyps usually increases with age, and the average age of colorectal cancer onset is 39.
There is also a type of FAP called attenuated FAP, in which polyps do not begin to grow until after that. The mean age of colorectal cancer onset for people with this form of FAP is 55. Both classical and attenuated FAP are caused by mutations in the APC gene.
The third type of FAP is autosomal recessive familial adenomatous polyposis, which is a milder form. People with this form develop fewer polyps. It is caused by a genetic mutation that is different from other types of FAP.

Lynch syndrome increases the risk of colorectal cancer, as well as cancers of the endometrium, ovaries, stomach, urinary tract, brain, and pancreas. An estimated 3% of colon cancer cases are caused by Lynch syndrome.
People with Lynch syndrome often develop colon cancer before the age of 50. They may have a family history of cancer, especially colon cancer. Lynch syndrome is caused by a dominant gene mutation, which means you only need to inherit the mutation from one parent to develop the condition.

Polyps associated with the MYH gene cause polyps in the colon and rectum, similar to the milder form of FAP. It is a recessive trait, which means you must inherit a mutation in the MYH gene from both parents to develop MYH-related polyploidy. Research on this condition is still in its early stages but suggests that it can significantly increase the risk of colorectal cancer.
There is also an inherited type of colon cancer called hyperplastic polyposis syndrome. It causes hyperplastic polyps, which are usually benign, but also increases the risk of colorectal cancer. Research is in the early stages and, at present, there are no genes associated with this syndrome.
MORE: Risk factors for colorectal cancer

Some measures to help reduce the risk of developing colorectal cancer:
Get regular checkups if you are over 50 or at increased risk. Eat lots of fruits, vegetables and whole grains. Eating more of these foods can lower your risk even further. Get most of your protein from poultry, fish, or legumes instead of red or processed meat. Do not smoke. Drink alcohol in moderation. Maintain a healthy weight. Exercise regularly (at least 30 minutes 5 days a week).

Many people with early-stage colorectal cancer do not have any symptoms. Therefore, it is important to get tested regularly if you are over 50 or at increased risk. There are several different tests that can help your doctor screen for and diagnose colorectal cancer:

Your doctor may use a scope - a camera on a thin, flexible tube to look at your colon and rectum. There are two types:
Total Colonoscopy : All people who are 50 to 75 years old and at normal risk for colorectal cancer should have a colonoscopy every ten years. A colonoscopy allows your doctor to see your entire colon and remove polyps and some cancers. It is also used to monitor other tests as needed.
Proctoscopy: This method uses a shorter scope than a colonoscopy and allows the doctor to see your rectum and lower third of your colon. If you choose to have a pelvic exam for screening, it should be done every 5 years, or every ten years if you have an annual stool immunohistochemistry test.

Out of scope, there are tests that look at your stool for signs of colorectal cancer. Includes:
Guaiac-based fecal occult blood test (gFOBT): Uses a chemical to detect blood in your stool. You get a kit from your doctor, collect the stool at home, then send the kit back for analysis. Fecal immunochemical test (FIT): Similar to gFOBT, but uses antibodies to detect blood in the stool. FIT-DNA test: Combines FIT with a test for DNA that is altered in your stool.

Symptoms of colorectal cancer include:
Rectal bleeding or blood in your stools Unexplained weight loss Diarrhea, constipation or other bowel changes that last at least four weeks Irritability or persistent abdominal pain, such as cramps Weakness and fatigue Pain in your lower abdomen Conclusion
Some cases of colorectal cancer are genetic, but in many others, the doctor Do not know the reason. And because early-stage colorectal cancer often doesn't cause any symptoms, early detection is essential. When detected early, colorectal cancer is treatable and curable.
Gastrointestinal cancer screening is a scientific and effective measure for early detection of gastrointestinal cancers (esophageal cancer, stomach cancer, colon cancer) and providing a good treatment plan. best. Vinmec International General Hospital has a team of leading doctors and nurses with extensive experience in the field of colorectal cancer diagnosis and treatment, supported by a system of modern technological equipment, complete with Professional means to diagnose disease and stage it before treatment such as: Laparoscopy, CT scan, PET-CT scan, MRI, Mammogram, histopathological diagnosis, gene-cell testing ... help detect colon cancer early even when there are no symptoms.

Reference article: Hyperplastic polyposis syndrome. Key statistics for colorectal cancer. (2018). Lee J, et al. (2015). Diet and lifestyle in survivors of colorectal cancer. Mayo Clinic Staff. (2018). Colon cancer.