ABSTRACT
Surgical Oncology Principals Background Cancer is responsible for over 500,000 deaths annually. It accounts for one quar
ter of all deaths in the US each year (Table 8.1).
Epidemiology Basic principles regarding population studies of cancer include the incidence of
a cancer and its prevalence. The incidence is the number of new cases reported in a population in a given year while the prevalence relates to the total number of diag nosed cases each year. Cancer is multifactoral in most instances and includes the interaction of genetic and environmental influences. Carcinogens may be in the form of physical agents (radiation), chemical agents (tobacco), and viral agents (hepa titis B virus). Ultimately, alterations in gene expression are the basis for all cancer.
