What is cancer caused by?
The malfunction or mutation of genes involved in cell division and cell proliferation.
Loss of differentiation. Cancer cells lose its ability to function normally, control growth, and control division.
Well differentiated. Tumor closely resembles the tissue of origin and retains some specialized function.
Moderately differentiated. Tumor has less resemblance to tissue of origin. More variation in size and shape of tumor cells; increased mitoses.
Poorly to very poorly differentiated. Tumor does not closely resemble tissue of origin. Much variation in size and shape of tumor cells; greatly increased mitoses.
Very poorly differentiated. Tumor has no resemblance to the tissue of origin. Great variation in size and shape of tumor cells.
Proliferation cells are transformed into different and more specialized cell types, which determines the microscopic characteristics of the cell, function, and lifespan. Adult cell has all its specific sets of characteristics and can no longer divide.
Benign tumor that has lost its ability to suppress the genetic program for cell replication but retain normal cellular differentiation.
Benign Neoplasm Properties
Capsule is mark of demarcation. Usually do not cause death. Known to secrete abnormal hormones.
Destructive tumors that grow rapidly, spread widely, and tend to cause death. Robs normal tissue from blood, nutrients, space, and release enzymes and toxins that destroy themselves and other tissues.
Destructive nature of Malignant Neoplasms due to:
Lack of cell differentiation, cell characteristics, rate of growth, and ability to spread and metastasize.
Tumors are classified on the basis of:
Tissue of origin, malignancy, degree of differentiation, and anatomic site.
Causes of Cancer: Gene-environment Interaction
Environmental agents cause cancer by increasing frequency of mutations such as cigarette smoke, carcinogens, x-rays, and UV light.
Causes of Cancer: Inherited Genes
Certain oncogenes can be inherited such as Retinoblastoma (childhood cancer of the eye), Wilms tumor (childhood cancer of the kidney), and breast cancer.
Causes of Cancer: Oncogenic Viruses
Cancer causing viruses that cause a specific type of malignant or benign tumor in susceptible individuals. Divided into 2 groups by nucleic acid: RNA and DNA viruses.
Cancer Development Stages (3)
1. Initiation - Causes irreversible changes to DNA after exposure to a carcinogen.
2. Promotion - Initiated cells become cancerous.
3. Progression - Cells become more biologically defective.
Process of specialization where by new cells acquire the structure and function of the ones they replace.
Cells That Do Not Proliferate or Divide
Well-differentiated neurons, skeletal cells, and cardiac muscle cells.
Undifferentiated Stem Cells
Cells that can enter the cell cycle and produce large numbers of parent cells when the need arises.
Spread of cancer cells from primary site of origin to distant site. The challenge of reducing cancer mortality is to control this.
3 Mechanisms of Metastasis
Direct or Continuous Extension
Metastasis in which tumors extend into several areas without breaking from the parent tumor which include tissue spaces, lymph and blood vessels, body cavities, and cerebrospinal spaces.
Metastasis by lymphatics involving the invasion and penetration of tumor cells into lymphatics. Tumor cells carried to the lymph nodes. Often, a mass in the region lymph node is evidence of this metastasis.