The American Cancer Society recommends that even people with no symptoms go see a physician for cancer screening. Early detection is one of the best weapons we have against cancer. Usually when a patient already has symptoms, the cancer has spread (metastasized). This makes curing it more difficult with the treatments offered today.

Both surgery and radiation are local treatments. That means they focus at a specific region of the body and will not cause any damage to tumor cells that "broke off" from the original tumor and spread to a distant site.

Even some of the new treatments in clinical trials today will not help cancers that have already metastasized. Some of these new drugs are aimed at preventing the tumor from growing large enough to invade and spread to other tissues (like angiogenesis inhibitors, which stop the growth of blood vessels and cut off the tumor's nutrient supply). If a tumor has already spread, these types of new drugs will not be of much help to the patient.

Chemotherapeutic agents and of course the presently evasive "magic bullets" of the future offer the best hope for metastasized tumors. When a "magic bullet" type of drug is developed in the future, administering it at an early stage versus a later one would always be more beneficial to a patient.

For these reasons, research efforts in the area of cancer are divided, not only into new treatments, but prevention and early detection. There are already several early detection methods presently used and many others are hoped for in the future.