What is colon cancer?


Colon cancer, also known as colorectal cancer, is a major health concern worldwide, being one of the leading causes of cancer-related fatalities. It is a type of cancer that begins in the large intestine (colon), which is the final part of the digestive tract. Early detection significantly improves prognosis, making knowledge about the causes, risk factors, and preventive measures vital.

What is Colon Cancer?

Colon cancer starts in the lining of the colon. Over time, benign (noncancerous) clumps of cells called polyps may form on the interior of the colon. While not all polyps become cancerous, certain types of polyps known as adenomas can develop into cancer over a period of many years if not detected and removed early.

Types of Colon Cancer

The vast majority of colon cancers are adenocarcinomas, which start in the cells that produce mucus to lubricate the inside of the colon and rectum. Other, rarer types include carcinoid tumors, gastrointestinal stromal tumors, lymphomas, and sarcomas.

What causes colon cancer?

The exact causes of colon cancer are not well understood. However, it is clear that colon cancer occurs when healthy cells in the colon develop errors in their genetic material. Over time, these errors cause the cells to divide uncontrollably, leading to the growth of tumors.

Genetic Mutations

Some colon cancers are caused by inherited genetic mutations that increase the risk significantly, though these cases make up a small percentage of overall occurrences. The two most common inherited conditions linked with higher colon cancer risk are familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome.

Risk Factors for Colon Cancer

Understanding the risk factors is crucial for prevention and early detection:

  • Age: The majority of people diagnosed with colon cancer are older than 50.
  • Ethnicity: African Americans have a higher risk of colon cancer than other races.
  • Family History: Having a parent, sibling, or child with colorectal cancer doubles one’s risk.
  • Personal History: Those with a history of colorectal cancer or adenomatous polyps are at increased risk.
  • Inflammatory Intestinal Conditions: Chronic inflammatory diseases of the colon, such as ulcerative colitis and Crohn’s disease, increase the risk of colon cancer.
  • Diet: A diet high in red meats and processed meats can increase colon cancer risk.
  • Physical Inactivity and Obesity: Being inactive and overweight increases the risk of colon and other cancers.
  • Smoking and Alcohol: Long-term smoking and heavy alcohol use are associated with increased colon cancer risk.
  • Type 2 Diabetes: People with diabetes or insulin resistance have an elevated risk of colon cancer.

Symptoms of Colon Cancer

In its early stages, colon cancer may be symptomless. However, symptoms can appear as it progresses and may include:

  • A persistent change in bowel habits, including diarrhea or constipation
  • Rectal bleeding or blood in the stool
  • Persistent abdominal discomfort, such as cramps, gas, or pain
  • A feeling that your bowel doesn’t empty completely
  • Weakness or fatigue
  • Unexplained weight loss

Diagnosis and Screening

Diagnosis usually involves a combination of procedures:

  • Colonoscopy: The most common test for diagnosis, allowing a doctor to view the entire colon and remove polyps.
  • Imaging tests: Such as CT scans of the colon, known as virtual colonoscopy, and other imaging like MRI.
  • Blood tests: Including tests to check for anemia and other signs that might indicate cancer.

Prevention and Early Detection

Screening is crucial because it can detect colon cancer in its earliest stages, or even before it has actually become cancerous. Regular screening should begin at age 45, or earlier for those at higher risk.

Diet and lifestyle play an essential role in prevention. Recommendations include increasing the intake of fruits, vegetables, and fibers; reducing red meat and processed meats; regular physical activity; maintaining a healthy weight; not smoking; and limiting alcohol consumption.


Colon cancer represents a significant health challenge but also one where preventive measures and early detection can profoundly impact outcomes. Awareness of risk factors and adherence to screening recommendations are integral to combating this common cancer. As research progresses, understanding of the genetic and molecular aspects of colon cancer continues to grow, opening new avenues for treatment and prevention.

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