Within a few short years, drug treatment of cancer has become an essential part of the practice of medicine. For many patients with different types of cancer, physicians are prescribing drugs with the expectation that they can increase length of life or, in advanced disease, provide relief of symptoms and an improved sense of well being. A few patients have been reported free of symptoms of acute leukemia and several other relatively rare types of malignancy for 5 to 10 years and even longer after treatment with drugs. These rare diseases include choriocarcinoma, which arises from the placenta; Burkitt's lymphoma, a type of cancer seen most frequently in African children; and Wilms' tumor, a type of kidney cancer in children probably of congenital origin.

These encouraging results flow directly from intensive laboratory and clinical research carried out independently and in many instances collaboratively by investigators throughout the United States and in Canada, Great Britain, and other parts of the world. During the past quarter of a century, and particularly the last 10 years, scientists engaged in cancer chemotherapy research have identified approximately 30 useful drugs and learned how to administer them, sometimes alone and often in combinations of two or more, to provide the patient the greatest benefit possible under present conditions of knowledge of the nature of cancer and the pharmacology of drugs.

Cancer is almost always a fatal disease if untreated. The primary methods of successful treatment are surgical removal of a tumor or destruction by irradiation, or a combination of both techniques. Improvements in the use of these methods since the early 1900's have gradually increased the 5-year survival rate to about 35 percent, or 1 out of 3 cancer patients. There is general agreement among physicians that patients who remain symptom-free about 10 years after treatment, and have the same progressive death rate from all causes as persons of the same age and sex in the general population, may be considered cured of their disease.

The outlook for long-term survival varies with the type of cancer and stage of the disease. In skin cancer, for example, the chance for cure is as high as 95 percent; other forms are invariably fatal in months. The conventional methods of treatment are not effective for cure of a majority of patients, whose disease is disseminated, such as in the leukemias and related lymphomas and in the so-called "solid" tumors that have spread to other parts of the body. These are systemic diseases, affecting the body as a whole. Hope for survival of patients with these diseases rests on successful development of a method such as chemotherapy, which will permit complete and selective destruction of cancer without harm to the patient. Chemotherapy may be used alone or in combination with surgery or irradiation, and perhaps in association with immunotherapy to enhance a patient's inherent defense mechanisms.

Efforts to find drugs for curing cancer are traceable to the early periods of recorded history. The ancient Egyptian papyri described the application of medicine to ulcerating skin tumors. In subsequent hundreds of years, thousands of chemical measures, including the use of heavy metals, reptile venoms, weird diets, and bacterial toxic products, were attempted for the treatment of malignant disease.