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Early detection tests identify cancer at an early and potentially treatable stage. Some tests can also prevent the development of colorectal cancer by identifying precancerous abnormal growths that can be removed before they become malignant.

Adults should be screened for early detection of colon cancer beginning at age 50 or earlier, depending on their risk of developing colorectal cancer. Several tests are currently available and each has its advantages and disadvantages. The optimal screening test depends on the patient’s preferences and individual risk of developing colon cancer.


Most colorectal cancers develop from precancerous polyps. Polyps are tumors that arise in the lining of the colon and are visible when the bowel is examined by endoscopy (colonoscopy or sigmoidoscopy).

There are two types of polyps, adenomatous and hyperplastic. Adenomatous polyps can become cancerous, but in most people it takes at least 10 years for this to happen.

Colon cancer screening is performed by detecting either polyps or cancer at an early stage, followed by removal of the abnormality. Regular colonoscopy reduces the risk of developing colorectal cancer by up to 90%. Early detection of cancers that are already present in the colon increases the likelihood of successful treatment and decreases the probability of dying as a result of this disease.


Several common characteristics increase the risk of colorectal cancer. Although each individual risk factor adds some risk, the risk is greatly increased if several of these factors are present at the same time.


1. Factors that increase risk:
Family history of colorectal cancer .

Having colorectal cancer in a first-degree relative (parents, siblings or children) increases the risk of cancer, as well as if several family members are affected or if the cancer occurred before the age of 55.

Personal history of colorectal cancer or polyps.

People who have previously had colorectal cancer have an increased risk of developing a new colorectal cancer. People who have had adenomatous polyps before age 60 also have an increased risk of developing it.


Although a person has a lifetime risk of 5% of developing colorectal cancer, 90% of these cancers occur in people over the age of 50. The risk increases with age throughout life.


Several lifestyle factors increase the risk of colorectal cancer, including:

  • A diet high in fat and red meat and low in fiber.
  • A sedentary lifestyle
  • Cigarette smoking
  • Alcohol consumption
  • Obesity

2. Factors that greatly increase the risk of colorectal cancer
Familial adenomatous polyposis.

Familial adenomatous polyposis (FAP) is a rare inherited disorder. Nearly 100% of people with this disease will develop colorectal cancer during their lifetime, and most of these cancers occur before the age of 50. PAF causes hundreds of polyps to develop along the colon beginning in adolescence.

Hereditary colon cancer without polyposis.

Also called Lynch syndrome is another inherited disease associated with an increased risk of colorectal cancer. It is slightly more common than FAP, but still rare, accounting for about 1 in 20 cases of colorectal cancer. About 70% of people with hereditary nonpolyposis colon cancer will experience colorectal cancer around age 65. The cancer also tends to occur at younger ages. People with hereditary nonpolyposis colon cancer are also at increased risk for other types of cancer, such as uterine, stomach, bladder, kidney and ovarian cancer.

Inflammatory bowel disease.

People with Crohn’s disease or ulcerative colitis have an increased risk of colorectal cancer. The increased risk depends on the amount of inflamed colon and the duration of the disease. Thus, pancolitis (inflammation of the entire colon) and colitis of 10 or more years’ duration are associated with an increased risk of colorectal cancer. The risk of colon cancer is not increased in people with irritable bowel syndrome.


3. Factors that may decrease the risk

Although some studies have shown that people who have higher calcium intake also have a lower risk of colorectal cancer, it is not known whether taking calcium supplements or eating a calcium-rich diet reduces the risk of cancer.

Aspirin, ibuprofen and other NSAIDs

Although there are studies that attribute to these drugs the ability to reduce the risk of developing colorectal cancer, the risk of developing other long-term side effects means that in routine clinical practice they are not recommended as prevention.


There is no consensus as to which colon cancer screening test is best. Therefore, an individualized strategy is recommended depending on the risk factors present.

Some experts recommend routine screening for precancerous polyps (colonoscopy or sigmoidoscopy). Others recommend CT colonography (virtual colonoscopy). Others, however, recommend regular fecal occult blood testing. But the reality is that it is decided which test is the most appropriate depending on the characteristics of the patient.


The recommended strategy for the early detection of colon cancer depends on the risk of the disease.

1. Intermediate risk for colorectal cancer:
Individuals at intermediate risk for colorectal cancer should begin screening at age 50, and one of the following screening strategies is recommended:

  • √ Colonoscopy every 10 years.
  • √ Virtual colonoscopy every 5 years.
  • √ Flexible sigmoidoscopy every 5 years.
  • √ Fecal occult blood test every 5 years

2. High risk of colorectal cancer.
In these individuals, the screening strategy involves early diagnosis at an earlier age, more frequent complementary tests or the use of more sensitive screening tests (usually colonoscopy). The optimal screening plan depends on the cause of the increased risk.

A. Family history of colorectal cancer

* People who have a first-degree relative with colorectal cancer or adenomatous polyps before age 60, or who have two first-degree relatives diagnosed at any age, should begin colon cancer screening before age 40, or 10 years before the age of the youngest relative with that diagnosis, whichever comes first. A colonoscopy is usually performed, and should be repeated every five years.

* Those with a first-degree relative with colorectal cancer or adenomatous polyps at age 60 or later, or two or more second-degree relatives (grandparents, aunts, uncles) with colorectal cancer, should begin screening by colonoscopy at age 50 and should be repeated as for intermediate-risk individuals.

* Those with a single second-degree or third-degree relative (great-grandparents or cousins) with colorectal cancer are considered to be at intermediate risk for colorectal cancer.


B. Those with a family history of genetically based colon cancer, such as familial adenomatous polyposis or hereditary nonpolyposis colon cancer, require aggressive screening and preventive treatments, and should be monitored by a physician with clinical expertise in these syndromes.


C. Individuals with ulcerative colitis or Crohn’s disease are at increased risk for colon cancer. The early detection strategy depends on how much of the colon is affected and how long the disease has progressed. In fact, in the routine follow-up of these patients, early detection of colon cancer is already included as standard practice.

CategoryCancer Care

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