Principles of early detection of cancer.

Screening for the early detection of cancer offers the potential of increasing the number of patients whose cancer is diagnosed in a localized, curable stage. The operation of an efficient and effective early detection program requires that a number of conditions be fulfilled, some of which are difficult to attain. First, the target population for screening should be defined demographically and epidemiologically so that the screening program is designed to be responsive to the needs of that group, e.g., age, ethnic composition, special occupational or environmental circumstances. Furthermore, an appropriate means of communicating with the reference population must be established so that the group can be educated regarding cancer prevention and detection and motivated to use early detection programs. Screening for early detection should be carried out on two levels: primary screening for the identification of risk factors, and prescriptive screening for additional procedures ordered according to the patterns of risk factors, and prescriptive screening for additional procedures ordered according to the patterns of risk factors identified. The screening encounter should be an opportunity for health education regarding primary prevention, as well as early detection of cancer. Screening without follow-up for diagnosis and treatment is likely to be counterproductive; the patient must be provided with a means of entering the health care system when this is indicated by the screening examination. Follow-up of suspicious findings must also be carried out for end-result evaluation. Primary screening can be carried out successfully by allied health personnel under most circumstances. A program employing these principles is now being utilized by a number of independent clinics in a voluntary collaborative program called "CANSCREEN." Examples of the operational modes of this program will be presented.