Colorectal cancer

Definition

Colorectal cancer is a type of cancer that begins in the colon or rectum, often developing from precancerous polyps in the digestive tract. It is closely linked to genetic factors and mutations in tumor suppressor genes and proto-oncogenes, which play critical roles in cell growth and division.

5 Must Know Facts For Your Next Test

1. Colorectal cancer is the third most commonly diagnosed cancer and a leading cause of cancer-related deaths worldwide.
2. Risk factors for colorectal cancer include age, family history, lifestyle factors like diet and physical inactivity, and certain genetic conditions.
3. Early-stage colorectal cancer may not present any symptoms, which is why regular screenings are recommended starting at age 45.
4. Tumor suppressor genes such as APC and proto-oncogenes like KRAS play significant roles in the development of colorectal cancer, with mutations leading to uncontrolled cell growth.
5. Treatment options for colorectal cancer often include surgery, chemotherapy, radiation therapy, and targeted therapies depending on the stage and genetic characteristics of the tumor.

Review Questions

• How do mutations in tumor suppressor genes and proto-oncogenes contribute to the development of colorectal cancer?
  • Mutations in tumor suppressor genes, such as the APC gene, remove critical controls on cell growth, allowing cells to divide uncontrollably. Similarly, mutations in proto-oncogenes like KRAS can lead to enhanced signaling for cell proliferation. Together, these genetic changes disrupt normal cellular processes and contribute to the formation of tumors in the colon or rectum.
• Discuss the role of adenomatous polyps in the progression to colorectal cancer and the importance of regular screenings.
  • Adenomatous polyps are precursors to colorectal cancer; they can develop into malignant tumors over time if left untreated. Regular screenings, such as colonoscopies, are crucial for detecting these polyps early on so they can be removed before they progress to cancer. By identifying and removing polyps during screenings, the risk of developing colorectal cancer can be significantly reduced.
• Evaluate how lifestyle choices can influence the risk of developing colorectal cancer and suggest preventive measures.
  • Lifestyle choices such as diet, physical activity, and smoking can significantly influence the risk of developing colorectal cancer. A diet high in red or processed meats may increase risk, while consuming a high-fiber diet with fruits, vegetables, and whole grains can help lower it. Regular physical activity is also beneficial for reducing risk. Preventive measures include maintaining a healthy weight, avoiding tobacco use, limiting alcohol consumption, and undergoing routine screenings starting at age 45.

Related terms

Adenomatous Polyps: Benign growths on the inner lining of the colon or rectum that can develop into colorectal cancer if not removed.

APC Gene: A tumor suppressor gene that, when mutated, can lead to familial adenomatous polyposis and increase the risk of colorectal cancer.

KRAS Gene: A proto-oncogene that, when mutated, can promote the development and progression of colorectal cancer by driving uncontrolled cell division.