Causes of cancer; Carcinogenesis Flashcards
(20 cards)
What is a mutagen?
A factor that brings about a mutation.
What is a carcinogen?
An agent that causes cancer.
Are all mutagens carcinogenic?
No, but some mutagens are carcinogenic.
What are the main classes of cancer-causing agents?
Chemicals, Radiation, Infectious agents, Heredity.
What is carcinogenesis?
A multistep process involving accumulation of multiple mutations leading to cancer.
What happens during initiation of carcinogenesis?
DNA mutation converts normal cells to a precancerous state.
What happens during promotion of carcinogenesis?
Stimulates initiated cells to proliferate and form tumors.
What happens during progression of carcinogenesis?
Further mutations create variant cells with selective growth advantage.
How does a normal cell become genetically altered?
By mutation through mis-copying or damage by carcinogens.
What happens after the first mutation in a cell?
The mutated cell and its descendants reproduce uncontrollably.
What leads to a second mutation?
Unchecked reproduction over time increases the chance of a second mutation.
What is the result of a third mutation?
Cells grow more vigorously and aggressively.
What happens after a fourth mutation?
Tumor grows rapidly but is still contained within tissue.
What marks the beginning of cancer invasion?
Cells break through the basement membrane.
What is angiogenesis?
The formation of new blood vessels to supply the growing tumor.
When is a tumor detectable?
When it grows large enough (about the size of a small grape).
What is metastasis?
The spread of tumor cells to other parts of the body to form secondary tumors.
How do tumor cells metastasize?
By entering blood vessels, traveling, and invading distant tissues.
How many tumor cells typically survive to establish a secondary tumor?
Less than 1 in 10,000 tumor cells.
Why are secondary tumors dangerous?
They establish new sites of cancer and are the major cause of lethality.
