Colon cancer, which affects the large intestine, is one of the most common cancers. Doctors usually group it with rectal cancer in a category called colorectal cancer. Colorectal cancer ranks third in men and second in women. It is the second leading cause of cancer death in men and the third in women.
The colon and rectum are part of the digestive system. The colon is about 1.5 m long and represents the major part of the large intestine. The rectum is the very last part of the large intestine and is considered the passageway between the colon and the anus. Colorectal cancer occurs when abnormal cells in the colon or rectum grow out of control, crowding out healthy cells.
Over 96% of colon and rectal cancers are adenocarcinomas. Adenocarcinomas are cancers that start in the glandular (secretory) cells found in the tissues that line certain internal organs. Glandular cells produce mucus that lubricates the colon and rectum.
Colon and rectal cancers usually start as abnormal growths, called colorectal polyps, in the lining of the colon or rectum. Many people with polyps do not develop cancer. People with a large polyp (over a centimeter), multiple polyps, or a polyp with dysplasia (abnormal but not yet cancerous cells) are most at risk.
The importance of colon cancer screenings
Getting regular screening tests is essential to prevent colorectal cancer. These tests allow doctors to look for this cancer in the general population, by evaluating people who have no symptoms of the disease. Screenings can help doctors find and remove colorectal polyps before they turn cancerous. It takes 10 to 15 years for new polyps to turn into cancer.
Screenings can also detect colon cancer and rectal cancer at an early stage, when these diseases are most treatable. If colorectal cancer is detected locally, before it spreads beyond the colon or rectum, the five-year survival rate is about 90%. Unfortunately, only just over a third of all colon and rectal cancers are detected at this early stage, largely due to inadequate screening.
What are the warning signs of colorectal cancer?
The presence of blood in the stool, a change in bowel habits marked by constipation or diarrhea, fatigue, weakness, abdominal pain, bloating and weight loss are some of the warning signs of colorectal cancer.
How long does it take for colorectal cancer to develop?
Most cases of colorectal cancer begin with a polyp, and it can take up to 10 or 15 years for it to become cancerous. That’s why regular screening to identify and remove polyps is the best way to prevent colon cancer.
Are colon cancer, rectal cancer and colorectal cancer all the same?
Colon cancer starts in the colon and rectal cancer starts in the rectum, but both areas are part of the digestive system. For this reason, cancers that arise in either of these areas are sometimes called colorectal cancer.
Can you die from colorectal cancer?
Yes. The chances of survival are higher for colorectal cancers detected at an early stage. For example, localized colorectal cancer that has not spread outside of the colon or rectum has a five-year survival rate of 90%, while cancers that have spread to nearby or distant organs have five-year survival of 75% and 14%, respectively.
Where is the first place colorectal cancer spreads?
Colon cancer usually spreads to the liver first, but it can spread to other parts of the body, including the lungs and brain.
Causes and risk factors of colon and rectal cancer
What causes colon cancer and rectal cancer? Researchers are still trying to fully answer this question.
They know, however, that a small number of people develop colorectal cancer due to rare genetic mutations passed down through their families. Yet for the vast majority of patients, colorectal cancer reflects a complex interplay between genetics and lived experiences. A very small number of colorectal cancers are probably caused by mutations inherited from parents. Most genetic mutations are acquired, that is, they occur during life. In some cases, a mutation in the APC gene, which normally controls cell growth, may play a role.
Doctors have identified a number of factors related to colon cancer risk and rectal cancer risk that increase a person’s chance of developing the disease. Weight, level of physical activity and diet seem to have a stronger link with these cancers than with any other type of cancer.
Risk factors that a person can modify
– Obesity or excess weight, especially in the stomach.
– A physically inactive lifestyle
– A diet that includes lots of red meat (beef and lamb) and processed meat (some lunch meats and hot dogs)
– Heavy alcohol consumption
Risk factors beyond control
– Age (although individuals can develop colorectal cancer at any age, people over 50 are most at risk).
– A personal or family history of colorectal cancer or polyps
– Personal history of inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis.
– Rare inherited genetic syndromes, such as Lynch syndrome
Prevention of colon and rectal cancer
The best way to prevent colorectal cancer is to stop it before it starts. First things first: Don’t smoke. Although people associate cigarette smoking with lung cancer, they are less aware of its strong link to colorectal cancer.
Other ways to prevent colon cancer and rectal cancer include maintaining a healthy weight, exercising regularly, not drinking moderate or heavy alcohol, and eating a healthy diet. limiting red and processed meats. Following the recommended schedule for screening tests, such as colonoscopies, can also help doctors find and remove potentially precancerous growths called polyps. The elimination of polyps detected by screening is one of the reasons why the death rate from colorectal cancer has decreased in recent decades.
Signs and Symptoms of Colon Cancer
Colorectal cancer can be difficult to detect at an early stage, as it may not cause symptoms until later stages. When symptoms do appear, it’s easy to blame them on another cause, such as hemorrhoids or irritable bowel syndrome.
When in doubt, the best decision is to consult a doctor as soon as possible.
The most common symptoms are:
– A change in bowel habits, such as diarrhea, constipation or narrowing of stools, that lasts for more than a few days.
– A feeling of need to have a bowel movement that is not relieved by defecation
– Rectal bleeding with bright red blood
– Presence of blood in the stools, which can give them a dark appearance
– Cramps or abdominal pain
– Weakness or fatigue
– Unexplained weight loss
Stages of colon and rectal cancer: What they can tell you
Staging colorectal cancer, or describing the extent of disease, helps doctors make treatment decisions and predict outcomes. For colon cancer and rectal cancer, doctors look at imaging tests such as computed tomography (CT) scans and other tests to determine if the cancer is limited to the inside lining of the colon or rectum. Whether it has grown in the lining of the colon or rectum, spread to nearby lymph nodes, or metastasized to other organs or sites in the body. Doctors quantify all of this information to determine a stage ranging from 0 to 4. In general, the lower the stage, the less advanced the disease, and the better the prognosis.