Colorectal cancer or colon cancer includes any type of neoplasms of the colon, rectum, and appendix. They begin as polyps in the intestinal mucosa that, for various reasons, evolve into malignant tumors. It is the third most diagnosed cancer in the world. Its prevalence is about 370 cases per 100,000 inhabitants.
Colorectal cancer
Colon cancer is one of the most diagnosed tumors on the planet. The exact cause that triggers the tumor is currently unknown, but risk factors that significantly contribute have been identified.
- Sex: Colon cancer is more common in men than in women, with an estimated diagnosis of 1 in 23 men and 1 in 24 women.
- Age: Although it can appear at any age, most affected individuals are over 50 years old.
- Ethnicity: It is more common in people of African American descent.
- Personal history of cancer or polyps: People who have had non-cancerous polyps in the colon are more predisposed to developing the disease.
- Inflammatory bowel conditions: Crohn's disease and ulcerative colitis increase the risk.
- Hereditary syndromes such as familial adenomatous polyposis or Lynch syndrome.
- Lifestyle: Diets with lower amounts of fiber and the consumption of ultra-processed foods, as well as a sedentary lifestyle, contribute to the increased risk.
- Obesity.
- Smoking.
- Diabetes.
Symptoms
It is very common for colon cancer to have no symptoms in the early stages of the disease. When symptoms do appear, they can vary slightly depending on their location, and may include:
- Blood in the stool.
- Changes in bowel habits, including diarrhea or constipation, or changes in the consistency of the stool.
- Abdominal discomfort with cramps, gas, and/or pain.
- Sensation of incomplete evacuation.
- Unexplained weight loss.
Prevention
Colon cancer screening programs have been a great advance for early diagnosis, making the prognosis, in most cases, very favorable. Due to the important role of genetics and the heritability of colon cancer, it is recommended that all people over 50 years old, with a family history of the disease, undergo these early detection tests.
Additionally, there are other measures that can be taken to reduce risk:
- Preferential consumption of fruits, vegetables, and whole grains, avoiding the consumption of ultra-processed foods.
- Avoiding alcohol and tobacco consumption.
- Engaging in regular physical exercise.
- Maintaining a healthy body weight.
In people at high risk of colon cancer, there are some medications that can reduce the risk of developing precancerous polyps. In these cases, it is recommended to consult a doctor.
Number of observed variants
13.5 million variants
Number of risk loci
74 loci
Genes analyzed
Bibliography
Law PJ, Timofeeva M, Fernandez-Rozadilla C, et al. Association analyses identify 31 new risk loci for colorectal cancer susceptibility. Nature Communications. 2019 May;10(1):2154.
Centers for Disease Control and Prevention (CDC) [March 2022]