In Knudson’s paper Two genetic hits (more or less) to cancer he talks about the chromosomal abnormalities, both in number and in structure, which are found in cancers. Prior to molecular biology, cancer researchers who studied both human and animal cancers thought that a small number of events were needed for carcinogenesis. Evidence found recently in the molecular biology suggests that cancers can be caused by a small number of events, which affect common cell birth and apoptosis. Cancer cells, like humans experience birth, development, and death. In some there are not many changes while in others there is an astounding number of abnormalities. In tumors with a single defect it seems more likely that a successfully targeted therapy will be …show more content…
R can be estimated for all different kinds of cancers and is equal to 6 for colon cancer. A fall back is that the mutation rate can change with time and other influences such as onset of smoking which increases the mutation rate due to the mutagenic nature of tobacco. Cancers have different peaks of incidences for example, incidence of childhood cancers peak in early life, osteosarcoma has an increasing incidence during adolescence, and breast cancer incidence increases more slowly after menopause. Polyps are cells, which clearly have a growth advantage that leads to benign neoplasm. A log-log plot of age specific colon cancer incidence in people with FAP should show a slope compatible with one less somatic event (r=5) since they have an inherited mutation that predisposes them to colorectal cancer. R for FAP is equal to 3-4, which exposes how intermediate growth advantage can affect the relationship to age. Richard Doll and Peter Armitage, fitted cancer incidence curves to two mutation curves which took growth advantage into account and found the confounding effect of intermediate growth advantage on number of hits inferable from incidence curves. The advantage was later deemed a result of increase in cell birth rate and a decrease in cell death rate. It can be concluded that age-specific