What follows is information available in more detail in a book called REAL AGE by Michael F. Roizen, M.D. Dr. Roizen's book and the related website and daily "tips" are one of the many resources I will recommend to you (see Appendix A). Cancer means the growth of tumors. It’s a category that includes a broad range of diseases. About 5 to 10% of all cancers stem from inherited genes.

The other 90 to 95% are caused by genetic “mistakes” which develop over your lifetime. Mutations in your DNA after you are born are these mistakes. We accumulate them. Cancer is a disease of our DNA. This is the substance that regulates the growth of the body. It is contained in every cell we have. It is the “instruction book” for your body. It determines the color of our eyes, how tall we are, that we have an arm instead of a wing…

If you have a computer and I give you two manuals, each three inches thick, you’ll never learn to use your computer. But if I tell you to read pages 10 through 15 and you will learn how to use your computer, you will do that.

When your body needs a cell, at the last minute it decides if it needs a kidney, eye or fingernail cell. The body then tells that cell which pages of the DNA to read. When it takes the place of a dying cell, it begins to function in that capacity. This DNA is duplicated with every cell division. Average adults have 75 trillion cells in their body.

Once again – 75,000,000,000,000 cells. 99% of the cells in our bodies are called “somatic” cells. All of them except brain and nerve cells get replaced thousands or hundreds of thousands of times during our lifetime. In seven years this process of cell division and death replaces virtually every cell in our bodies. Another way to look at this is that every day about 205 billion cells get replaced in our body. Why is this important? Because cancer is caused by mutations that occur during this process.