Cancer Overview

Cancer is the second leading cause of death in the United States, accounting for one in four deaths. The American Cancer Society estimates that in 2007, 1.44 million new cases of cancer will be diagnosed in the United States and nearly 560,000 individuals will die from cancer. The incidence of cancer continues to increase and is expected to increase as the leading edge of the "baby boom" generation turns 55 years old, the age at which cancer incidence begins to rise sharply. Seventy-seven percent of all cancers are diagnosed in patients age 55 or older.

Surgery, radiation, and chemotherapy are the three primary methods of treating cancer. Patients whose cancers have not yet metastasized (spread beyond the primary site) by the time of detection are generally treated through surgery or radiation. Surgical removal of some tumors is impossible because of their location or the extent of organ infiltration. Radiation produces ionized molecules within the body that attack cancer cells, but also damage healthy surrounding cells. This side effect limits the amount of radiation that can be used and thus its effectiveness. Nonetheless, surgery and radiation offer the most hope for treating tumors that have not yet spread. When cancers have metastasized by the time of detection, surgery and radiation are generally ineffective, making chemotherapy one of the few treatment options. Unfortunately, most conventional cancer drugs are poorly-targeted toxins that can only be used acutely, produce debilitating side effects, and are of limited efficacy: half of those who develop cancer die from it.

The great majority of anti-cancer drugs work by destroying rapidly-dividing cells. Cancer chemotherapies have historically been the only accepted treatment for malignancies that have metastasized. Because chemotherapies are given systemically, they can reach most parts of the body, including metastatic tumors. Unfortunately, chemotherapies do not distinguish between rapidly growing healthy cells and cancer cells. This leads to serious side effects and a very narrow dosing window in which the drug is effective but not fatal. Often, treatment must be discontinued due to adverse effects or cumulative toxicities, rendering chronic treatment impossible. Since the tumors are generally not completely eradicated by the chemotherapy, cessation of treatment often leads to a regrowth of the malignancy. In addition, many tumors mutate rapidly and develop resistance to the chemotoxic drugs thereby rendering further treatment ineffective.

Recently, newer agents have been developed that target specific components of cancer tissues. Drugs that prevent blood vessels from forming and feeding tumors have shown activity. These so-called anti-angiogenic agents have shown activity in a variety of tumor types including colon, breast, lung and kidney cancers. Other agents target cell pathways that are more common in tumor cells than normal cells, and have antitumor activity with limited effects on normal tissues, although they are not devoid of toxic effects.