Screening for cancer. Is it worth it?

A delay in diagnosing cancer is widely perceived to compromise severely a patient's chance of being cured. The unrealistic expectations of technology and of physicians' capabilities are inconsistent with modern knowledge of the natural history of cancer. Established and recent precepts in clinical oncology and tumor biology emphasize that inherent characteristics of a malignant neoplasm predict its dissemination, rather than a real or perceived delay in diagnosis. The processes of carcinogenesis and dissemination are more nearly simultaneous than sequential. Uncritical belief in the ability of most cancer screening techniques to provide cure through early detection may do more harm than good. Policy and efforts would be better directed to the primary prevention or reversal of preneoplasia and to improved therapy for established cancer.