How Does Colorectal Cancer (CRC) Develop?
CRC originates from cells in the large bowel. Throughout the life of an individual cells accrue mutations in their DNA. Mutations make cells heartier and enable them to grow a little better than their normal surrounding cells. Eventually these cells expand into a little mound in the interior of the colon. This little mound is called a polyp. Not all polyps will turn into a cancer but some, if left inside the colon for long time, can transform into a cancer. This process in the majority of cases is very slow and can take anywhere from 10 to 15 years. Sometimes the process can take place quicker, particularly when there is a strong family history of CRC.
What are the signs and symptoms of CRC?
In most instances there are no specific symptoms. This is usually the case for pre-cancerous polyps and small colon cancers. As the cancer grows telltale signs begin to appear. These include blood in the stool, a change in bowel habits (progressive constipation), changes in the shape of the stools such as thinner tools; weight loss, and fatigue. Fatigue can be a sign of anemia. Anemia frequently occurs in CRC due to slow blood loss. Sometimes anemia is the earliest presentation of CRC.
Risk factors for CRC
Risk factors can be divided into those that can’t be controlled and those that can be controlled. Within the factors that cannot be controlled the main one is age. CRC becomes more common as people age. The risk begins to increase after the age of 40 and rises significantly at ages 50 to 60. The risk doubles with each following decade. Other important factors that cannot be controlled include a family history of polyps or CRC, other cancers such as uterine cancer, a personal history of colon rectal polyps, personal history of inflammatory bowel disease, and inherited CRC syndromes such as hereditary non-polyposis colorectal cancer syndrome (HNPCC). Risk factors that can be controlled include factors that are linked to things that you do that increase your risk for CRC such as consuming a diet high in red meats and processed meats, cooking meat at high temperatures such as in a grill (increased temperature can create toxins that cause mutations in cells), sedentary lifestyle, obesity, smoking, and excess alcohol use.
How can CRC be prevented?
Studies have found increase body weight can predispose to CRC. This link seems to be stronger in men, particularly when the increased weight is distributed around the waistline. Other studies show that consuming diets low in vegetables and whole-grain can predispose to CRC. Finally polyps and CRC are found more frequently in individuals with low levels of physical activity. To help prevent colon cancer start with behavior modification. Increase your physical activity. Scheduled episodes of vigorous activity several times a week maybe more beneficial than moderate activity on a regular basis. Eat more vegetables, fruits, and whole-grain foods and consume less red meat and processed meat. Make it a key goal to lose weight: increase your aerobic exercise and focus on losing the fat around the waistline. Lastly, participate in CRC screening programs. The incidence and mortality of CRC has dropped in the last several years, possibly due to multiple available screening methods capable of detecting precancerous lesions. A colonoscopy is the best screening method since it can look at the whole colon, detect polyps, and remove them during the same procedure. It is recommended that people with no family history of CRC have their first colonoscopy at age 50. If no precancerous polyps are seen the colonoscopy can be repeated in 10 years. Patients with a strong family history of CRC should undergo their first colonoscopy sooner, and patients with a history of precancerous polyps should have their follow-up colonoscopy done at shorter intervals. Talk to your primary care doctor or get referred to a gastroenterologist to find out when and how often you should get screened for CRC.
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