Biomedical Science - Unit 1 Cancer

Cancer

Process of uncontrolled cell division, developing slowly over a period of years

Benign Tumors

Not cancerous, usually confined by a fibrous capsule, and may maintain normal cell function. Only harmful if they grow to be very large or secrete large amounts of hormones to surrounding tissues

Malignant Tumors

Cancerous, grow more rapidly, evade death and eventually become invasive (metastatic). Heterogeneous in composition

Carcinomas

Cancers of epithelial tissue (80-90% of all cancers)

Sarcomas

Cancers of supportive and connective tissue

Myelomas

Cancer of plasma cells (in bone marrow)

Leukemias

Cancers of blood cells

Lymphomas

Cancers of the lymphatic system (glands/nodes)

Cancer Cause

A series of genetic mutations that collectively lead to unregulated growth and survival.

How Mutations Arise

1. Spontaneous random mutation in DNA replication
2. Environmental exposure to carcinogens
3. Inherited – so mutation was in the germ cells (egg or sperm)

Environmental Factors

Radiation: UV, X-Rays; Chemicals: Carcinogens (ex. cigarettes, alcohol), Processed Food and Preservatives, Cosmetics and Cleaning Products; Infectious Agents: Viruses (ex. HPV), Bacteria (ex. Helicobacter)

Cell Cycle

1. Mitosis, cell divides

2. G1, cell grows in size (first gap)

3. S, DNA/chromosome synthesis

4. G2, organelles replicate (second gap)

Checkpoints

When cells arrest at certain points if certain criteria isn’t met

G0

An exit from the cell cycle, so cells in this are usually differentiated cells or cells receiving no signals to grow.

Proto-oncogenes

“Gas” on cell division

Tumor Suppressor Genes

“Brakes” on cell division

Antioxidants

Neutralize free radicals by giving up some of their own electrons. In
making this sacrifice, they act as a natural "off" switch for the free radicals. This
helps break a chain reaction that can affect other molecules in the cell and other cells in the body.

Angiogenesis

The process by which tumors cause the body to provide them with nutrients

Growing Tumors

Saying “feed me” - messages cause blood vessels to send over new extensions that deliver food and oxygen.

Blood Vessels

Also serve as passage ways for the movement of tumor cells to neighboring and distant parts of the body

Metastasis

Movement of tumor cells to other parts of the body. Cancer cells form new tumors.