How do tumors form?

when cells grow and divide at an abnormal rate

another word for tumor


Neoplasms are classified as _______ or _______.

benign or malignant

Benign tumors:

- local
- often encapsulated
- tend to grow slowly
- seldom kill their hosts if removed before they compress vital organs

Malignant tumors:

- non encapsulated
- spread to other parts of the body
- grow relentlessly

Cancer cells are also called _______.

malignant neoplasms

Define metastasis

spread of a tumor from its site of origin to distant sites

_________ and _______ distinguish cancer cells from the cell of benign neoplasms.

Metastasis and invasiveness

What changes a normal cell into a cancerous one?

radiation, mechanical trauma, certain viral infections, chronic inflammation, many chemicals, and toxins

The factors that change a normal cell into a cancerous one cause ________.


What are carcinogens?

substances that gives rise to cancer; a cancer forming agent

What are the defenses the body has against carcinogens?

- the liver inactivates many of them
- cells have intrinsic DNA repair mechanisms to help undo mutations
- some immune system cells continuously scan the body cells and eliminate any cancerous cells they find

What are oncogenes?

cancer causing genes

What are proto-oncogenes?

benign forms of oncogenes in normal cells

Oncogenes accelerate growth while the products of __________ inhibit cell growth and division.

tumor supressor genes

What is adenoma?

neoplasm of glandular epithelium

What is carcinoma?

cancer arising in an epithelium; accounts for 90% of human cancers

What is sarcoma?

cancer arising in the mesenchyme-derived tissues, that is, in connective tissues and muscles

What is mesenchyme?