The development and progression of cancer is a complex and
multistep process in which a series of changes culminates in
deregulation of cell proliferation in somatic cells. Although
the specific genetic and epigenetic events leading to cancerous
growth differ among tumor types, a number of affiliated cellular
pathways have now been identified. Genes that may be involved in
these processes include those that influence proliferation rate,
apoptosis, genomic stability, differentiation, adhesion, and
angiogenesis. Alterations in these genes may act in a dominant
or recessive fashion and are caused by amplifications, point
mutations, deletions, or structural rearrangement. Recent data
suggest that some abnormalities occur at an earlier stage than
others, and these initial markers may be important for prognosis
and early detection. Identified more than 15 years ago, one of
the first abnormalities found in lung cancer was the loss
(deletion) of chromosomal material on the short arm of
chromosome 3. Since then, an in