ABSTRACT
With approximately a half million deaths annually, cancers are second only to heart diseases among causes of death in the U.S., accounting for 20% of all fatalities in the U.S. Breast cancer, lung cancer, and colorectal cancer are the most common cancers in women; prostate cancer, lung cancer, and col-
orectal cancer are the most common cancers in men. Cancer incidence is higher among blacks than whites, and among males than females. Cancer incidence is much higher among the middle aged and elderly than among young people; this is most likely due to the multiple steps and latent period that characterize most forms of cancer.
