Colorectal cancer

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/100,000 inhabitants.

Colon cancer is one of the most commonly diagnosed tumors on the planet. The exact cause that provokes the appearance of the tumor is currently unknown, but risk factors that contribute significantly have been identified.

  • Sex: Colon cancer is more frequent in men than in women, and it is estimated that it will be diagnosed in 1/23 men and 1/24 women.
  • Age: Although it can appear at any age, most of those affected are over 50 years of age.
  • Ethnic origin: it is more frequent 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 the disease.
  • Inflammatory bowel conditions: Crohn's disease and ulcerative colitis increase the risk.
  • Inherited syndromes such as familial adenomatous polyposis or Lynch syndrome.
  • Lifestyle: low-fiber diets and consumption of ultra-processed foods, as well as sedentary lifestyles contribute to increased risk.
  • Obesity.
  • Smoking.
  • Diabetes.

Colorectal cancer is one of the leading causes of cancer-related death worldwide and has a strong genetic basis. Among the studies carried out, an association study with some 35,000 cases and more than 700,000 controls in which 74 susceptibility loci were identified stands out. Among the SNPs identified, those associated with signaling pathways such as Wnt and BMP, previously reported in other studies, stand out. In addition, other previously unrelated novel loci have been identified and provide valuable information to identify potential novel targets for chemoprevention and chemotherapeutic intervention.


It is very common for colon cancer to present no symptoms in the early stages of the disease. When they do appear, they may vary slightly depending on their location, and may include:

  • Blood in the stool.
  • Changes in bowel habits, including diarrhea or constipation, or changes in stool consistency.
  • Abdominal discomfort with cramping, gas and/or pain.
  • Sensation of incomplete evacuation.
  • Weight loss without apparent cause.


Colon cancer screening programs have been a great advance in 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 everyone over the age of 50 with a family history of the disease undergo these early detection tests.

In addition, there are other measures that can be taken to reduce the risk:

  • Preferential consumption of fruits, vegetables and whole grains, avoiding the consumption of ultra-processed.
  • Avoid consumption of alcohol and tobacco.
  • 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 precancerous polyps. In these cases, it is recommended to consult a physician.

Number of observed variants

13.5 million variants

Number of risk loci analyzed in the study

74 loci


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.

Mayo Clinic [March 2022]

Centers for Disease Control and Prevention (CDC) [March 2022]

The DNA test you were looking for