Metastasis

Definition

Metastasis is the process by which cancer cells spread from their original site to other parts of the body, forming new tumors. This process is a key characteristic of malignant tumors, distinguishing them from benign tumors, which do not invade surrounding tissues or spread. Understanding metastasis is crucial for grasping how cancer progresses and why it can be more difficult to treat once it has spread.

5 Must Know Facts For Your Next Test

1. Metastasis often occurs through the bloodstream or lymphatic system, allowing cancer cells to travel and establish new tumors in distant organs.
2. Common sites for metastasis include the lungs, liver, brain, and bones, depending on the type of primary tumor.
3. The process of metastasis involves multiple steps, including local invasion, intravasation (entry into blood vessels), survival in circulation, extravasation (exit from blood vessels), and colonization of new tissues.
4. Tumor suppressor genes and proto-oncogenes play a critical role in regulating cell growth and division; mutations in these genes can lead to increased risk of metastasis.
5. Metastatic cancer often requires different treatment strategies than localized cancer due to its complexity and ability to resist standard therapies.

Review Questions

• How does the process of metastasis differentiate malignant tumors from benign tumors?
  • Malignant tumors have the capability to invade surrounding tissues and spread to other parts of the body through metastasis, while benign tumors remain localized and do not infiltrate nearby structures. This ability to metastasize is a defining characteristic of cancer that contributes to its severity and challenges in treatment. Understanding this distinction helps in identifying the nature of a tumor and determining appropriate therapeutic approaches.
• Discuss the role of tumor suppressor genes and proto-oncogenes in relation to metastasis and how their mutations can influence cancer progression.
  • Tumor suppressor genes function to regulate cell growth and prevent uncontrolled division, while proto-oncogenes promote normal cell proliferation. Mutations in these genes can lead to unregulated cell growth and increased likelihood of metastasis. When tumor suppressors fail or proto-oncogenes become oncogenes due to mutations, it enhances the cancer's ability to invade surrounding tissues and spread throughout the body, making treatment more challenging.
• Evaluate the implications of angiogenesis in the metastatic process and how targeting this process could change treatment outcomes for cancer patients.
  • Angiogenesis plays a crucial role in providing tumors with the necessary blood supply for growth and spread. As tumors grow and metastasize, they trigger angiogenesis to facilitate nutrient delivery. By targeting angiogenesis therapeutically, it's possible to disrupt the blood supply that fuels metastatic tumors, potentially limiting their growth and spread. This approach could lead to improved outcomes for patients by effectively managing metastatic disease and preventing further dissemination.

Related terms

malignant tumor: A type of cancerous growth that has the ability to invade nearby tissues and spread to other parts of the body.

angiogenesis:

The formation of new blood vessels, which tumors need for nutrients and growth, often facilitating metastasis.

invasion:

The direct penetration of cancer cells into adjacent tissues, which can precede the process of metastasis.