Seven years ago I was found to have colon cancer. After the surgery to remove the tumor, I was introduced to chemotherapy.

After each weekly visit to the oncologist blood was drawn the purpose of which was determine platelet population and to test for the reoccurrence of colon cancer.

My oncologist was kind enough to dampen my fears by explaining as best he could to a layman of how the markers and how testing the blood gave up so much information.

I was told that the same marker was used for some, but not all, other cancers that are related to colon cancer such as breast cancer.

Even now, when I go in for my annual check-up, they draw blood and test with a marker to see if there are any indications that a cancer may be growing anew.

As scientists grow increasingly savvy about the biochemical markers that contribute to health and longevity, it has become even more vital to obtain and interpret information that can be gleaned only through comprehensive blood testing. People who are genuinely committed to making informed deci­sions that impact their quality as well as their quan­tity of life are wise to take advantage of the hidden data about themselves that blood testing reveals. This strategy can help you maximize the benefits of regular exercise, healthy lifestyle choices, and appropriate nutritional supplementation.

Why should it be that we can learn so much about our bodies' function in health and disease through blood testing? The answer, of course as I was told, is that literally every cell in the human body is in constant communication with circulating blood. And since ultimately all communica­tion within the body takes place by means of chemical signaling, we simply need to "tune in" to the proper signal to learn about virtually any condition from appendicitis to zinc deficiency.

Blood is an ideal communications medium. A complicated tissue itself, blood contains a score of different cell types involved in functions ranging from oxygen delivery, to control of coagulation, to intricate immune system activities. The liquid portion of blood, which makes up roughly 60% of its volume, is not simply water, rather, it's a complex mixture of proteins, fats, nutrients, minerals, hormones, and other vital substances with constantly changing concentrations and char­acteristics. Crucially, blood also contains both normal waste products and chemicals that leak from diseased or damaged tissue, providing a highly sensitive "early warning" system that can alert us to incipient catastrophes or simply the need to make slight adjustments in our dietary intake or lifestyle.