Cancer Biology: Invasion, Metastasis, and Therapeutic Approaches
Invasion and Metastasis
Invasion
Invasion is the process by which cancer cells spread from their primary tumor to surrounding tissues and organs. It involves a series of steps, including:
- Hyperplasia: An increase in the number of normal cells in a tissue.
- Metaplasia: A change in the type of normal cells in a tissue.
- Dysplasia: Abnormal changes in the appearance and behavior of cells.
- Carcinoma in situ: Cancer cells that are confined to the tissue of origin.
- Invasive carcinoma: Cancer cells that have invaded surrounding tissues.
- Intravasation: Cancer cells entering blood vessels or lymphatic vessels.
- Survival in circulation: Cancer cells being transported through the bloodstream or lymphatic system.
- Arrest in distant organ: Cancer cells lodging in a distant organ.
- Extravasation: Cancer cells exiting blood vessels or lymphatic vessels.
- Micrometastasis: Small clusters of cancer cells in a distant organ.
- Metastatic colonization: Cancer cells growing and dividing in a distant organ.
- Macrometastasis: Large, detectable metastases.
Metastasis
Metastasis is the process by which cancer cells spread from the primary tumor to distant organs. It is a complex process that involves multiple steps, including:
- Angiogenesis: The formation of new blood vessels, which provide nutrients and oxygen to the growing tumor.
- Epithelial-mesenchymal transition (EMT): A process by which epithelial cancer cells lose their cell-cell adhesion and become more motile.
- Migration: The movement of cancer cells through the extracellular matrix.
- Intravasation: The entry of cancer cells into blood vessels or lymphatic vessels.
- Survival in circulation: Cancer cells being transported through the bloodstream or lymphatic system.
- Arrest in distant organ: Cancer cells lodging in a distant organ.
- Extravasation: Cancer cells exiting blood vessels or lymphatic vessels.
- Metastatic colonization: Cancer cells growing and dividing in a distant organ.
Hallmarks of Cancer
The hallmarks of cancer are a set of characteristics that distinguish cancer cells from normal cells. These hallmarks include:
- Sustained proliferative signaling: Cancer cells have the ability to divide uncontrollably.
- Evasion of growth suppressors: Cancer cells are able to bypass the normal mechanisms that control cell growth.
- Resistance to cell death: Cancer cells are able to resist apoptosis, or programmed cell death.
- Induction of angiogenesis: Cancer cells are able to stimulate the formation of new blood vessels, which provide nutrients and oxygen to the growing tumor.
- Activation of invasion and metastasis: Cancer cells are able to invade surrounding tissues and metastasize to distant organs.
Oncogenes and Tumor Suppressors
Oncogenes are genes that promote cancer development. They can be activated by mutations or other genetic changes that lead to the overexpression of the oncogene product. Tumor suppressor genes are genes that inhibit cancer development. They can be inactivated by mutations or other genetic changes that lead to the loss of function of the tumor suppressor gene product.
Targeted Therapy
Targeted therapy is a type of cancer treatment that uses drugs to target specific molecules that are involved in cancer growth and survival. Targeted therapies can be more effective than traditional chemotherapy drugs, which target all rapidly dividing cells in the body.
Chemotherapy
Chemotherapy is a type of cancer treatment that uses drugs to kill cancer cells. Chemotherapy drugs can be given orally, intravenously, or through other routes of administration.
Prognosis
The prognosis for cancer patients depends on a number of factors, including the type of cancer, the stage of the cancer, and the patient’s overall health. Prognosis can be estimated using a variety of tools, including the TNM staging system and the Karnofsky Performance Scale.
Screening
Cancer screening is a process of testing people who do not have any symptoms of cancer in order to detect cancer at an early stage, when it is more likely to be curable. Screening tests can include mammograms, colonoscopies, and Pap tests.