In this slide I have made a stab at ranking cancer risk factors on a relative basis based on current knowledge, but the research agenda is far from finished. Tobacco smoking is the major carcinogen responsible for about one-third of all cancer. Alcohol interacts with smoking in the development of certain cancers and has an independent affect on the risk of breast cancer, liver cancer and probably colorectal and pancreas cancer. Nutrition-related factors, especially obesity and physical inactivity, are important along with diet, but questions remain about the specific dietary components that are either carcinogenic or protective. Microbial agents, including viruses and bacteria, along with inflammatory state, seem likely to have a greater role than has been estimated at present. There is also a need to clarify the effects of chemicals from occupational exposures, air and water pollution, and pharmaceuticals along with... And pharmaceuticals, by the way, include hormones and we’ve heard this morning from Alice about the impact that exogenous estrogens, menopausal estrogens have played in the etiology of breast cancer. And we need to know more about ionizing radiation, especially from indoor radon and radioactive materials in the atomic age, not to mention UV radiation for skin cancer, including melanoma. It’s difficult to estimate the amount of cancer related to genetic susceptibility. I have lots of question marks here since only now do we have the tools to identify susceptibility or modifier genes and their interaction with environmental factors, which may, by the way, be easier to detect in susceptible subgroups of the population. While inherited genes may eventually be found to contribute to a sizable fraction of cancer, it is clear that at least one-half of cancer in the U.S. could be prevented by implementing changes in modifiable risk factors, some of which (like smoking and obesity) contribute to several forms of cancer.