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Kmno4

LECTURE 15. CANCER: DEVELOPMENTAL MECHANISMS AND ONCOGENESIS


Optional reading: Alberts et al., Molecular Biology of the Cell. Chapter 23.



A. DEFINITIONS:

1. Oncogenesis-The process whereby normal cells become cancer cells.

2. Tumor - a population of cells that result from the localized, unregulated growth and division of a single cell. Occurs in the face of normal restraints on growth. Also called a neoplasm.

3. Metastasis - the migration of cells from a tumor and their invasion of other tissues. Only
when tumors metastasize are they considered malignant or cancerous.


B. STATISTICS:

1. Approximately 0.6 million US citizens will die of cancer this year.

2. About 1.4 million new cases will be reported in this country this year.

3. Collectively, cancers are the #2 killer of Americans (behind cardiovascular disease) and account for almost 25% of all deaths.

4. Roughly 50% of all cancers are of the lung, intestine and breast. Nearly 150,000 women will develop breast cancer this year.


C. THE NATURE OF CANCER:

As has become appreciated over the years, cancer is not a single disease, but a whole collection of disorders that constitute at least 300 different histological types. These types can be grouped into a series of classes, based largely on the embryological origin of the initial tumor cells. Carcinomas are epithelial in origin (ectodermal and endodermal); sarcomas are derived from connective tissue (mesodermal); leukemias are from blood-forming cells; melanomas derive from pigment cells (melanocytes); and teratomas arise from germ cells or gonadal tissue.

Tumors are the result of localized, unregulated, cell growth. For a tumor to become malignant, cells must begin to metastasize (move), and invade, other tissues. The original tumor is called a primary tumor. and all the cells derive from single aberrant cell. As tumors metastasize the new...

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