Colorectal Cancer Causes and Risk Factors
Colorectal cancer is a tumor that develops in the colon or rectum, two parts of the large intestine that form the final section of the digestive tract. Typically, the cancer begins as a small, benign clump of cells (polyp) in the colon or rectum that gradually changes and becomes cancerous over time. This process can take up to several years.
Colorectal polyps are common, and most do not become cancerous. What’s more, precancerous polyps and early-stage colorectal cancer can usually be detected in a routine screening test, such as a colonoscopy, before noticeable symptoms develop. As the cancer progresses, it may begin to cause changes in bowel habits, such as persistent diarrhea or constipation, and bloody stool.
Colorectal cancer is one of the most common cancers worldwide. Although it is most frequently diagnosed after age 50, it can occur at any age. That said, it is highly treatable and can often be cured. Depending on the location and stage of the tumor, treatment may involve a combination of surgery, chemotherapy and radiation therapy.
What causes colorectal cancer?
Colorectal cancer primarily arises due to harmful cellular changes in the lining of the colon or rectum. These DNA mutations disrupt the normal regulatory pathways that control cell division and death, causing the cells to grow uncontrollably and survive beyond their normal lifespan. Over time, the abnormal cells can amass and form a tumor.
The cellular mutations that lead to the development of colorectal cancer can be inherited or acquired. Changes in key oncogenes and tumor suppressor genes, such as APC, KRAS and p53, are often found in colorectal cancer cells.
What are the risk factors for colorectal cancer?
Risk factors are characteristics, behaviors and exposures that can increase the likelihood of developing colorectal cancer, although they do not directly cause it. While some risk factors can be controlled, others cannot.
Colorectal cancer risk factors that can be controlled
By making healthy lifestyle changes, it may be possible to control certain colorectal cancer risk factors, such as:
- Poor nutrition – A diet high in red and processed meats and low in fruits, vegetables and whole grains has been linked to colorectal cancer.
- Physical inactivity – Lack of exercise and low levels of other physical activity can increase the risk of many types of cancer, including colorectal cancer.
- Obesity – Excess body fat, usually measured by a body mass index (BMI) of 30 or greater, can increase cancer risk.
- Smoking and drinking – Tobacco use and excessive consumption of alcoholic beverages are both well-established cancer risk factors.
Colorectal cancer risk factors that cannot be controlled
Certain colorectal cancer risk factors cannot be controlled, such as:
- Advanced age – The risk of many types of cancer, including colorectal cancer, increases with age.
- Health history – A personal history of colorectal polyps or cancer and a family history of colorectal cancer are both unavoidable risk factors.
- Inherited cancer predisposition syndromes – Familial adenomatous polyposis (FAP), Lynch syndrome, juvenile polyposis and Peutz-Jehgers syndrome are associated with colorectal cancer.
- Diabetes – Several studies have identified type 2 diabetes and insulin resistance as risk factors for colorectal cancer.
Can colorectal cancer be prevented?
Colorectal cancer cannot be prevented, but it may be possible to lower the risk by taking certain preventive steps, such as:
- Having regular medical check-ups – Most physicians recommend routine screening tests, such as colonoscopies, which can often detect precancerous polyps so they can be removed before they progress into colorectal cancer.
- Consuming a nutritious diet – Eating a diet rich in fruits, vegetables and whole grains and low in red and processed meats can help reduce cancer risk.
- Exercising regularly – Physical activity can reduce the risk of colorectal cancer and also help mitigate other risk factors, such as obesity and type 2 diabetes.
- Avoiding tobacco and limiting alcohol intake – Smoking cessation and drinking in moderation, if at all, are crucial preventive measures against many types of cancer, including colorectal cancer.
Frequently asked questions (FAQs) about colorectal cancer causes and risk factors
The following FAQs-related articles provide additional information about colorectal cancer causes and risk factors:
Benefit from world-class care at Moffitt Cancer Center
If you would like to learn more about colorectal cancer causes and risk factors, you can request an appointment with a specialist in Moffitt’s renowned Gastrointestinal Oncology Program by calling 1-888-663-3488 or submitting a new patient registration form online. We do not require referrals.