12. Searching for Cancer Biomarkers in Human Body Fluids

One of the important lessons learned about cancer survival from the past few decades’ experience in cancer treatment is: early detection is the key. It has now become common knowledge that as a cancer progresses from early to more advanced stages, it gradually changes from a local and relatively simple problem to a very complex health issue involving the body at large. Once a cancer has metastasized, tumors in the new locations tend to grow substantially faster and metastasize further and much more rapidly than the primary counterpart, hence making the disease considerably more difficult to control and treat. The available statistics show that the survival rate of a cancer patient drops substantially when an encapsulated tumor spreads to the neighboring tissue and then to distant locations. For example, the 5-year survival rate drops from 99 to 66 % and then down to 9.4 % when a colorectal cancer is localized, has spread to only the local tissue and then to distant organs, respectively. Similar survival statistics hold for virtually all cancers. It is particularly worth emphasizing that the 5-year survival rates tend to drop to single digits or low tens of percentages for most of the cancers when they have spread to distal organs.