Cancer screening in the USA.

Once screening for cancer has been shown to be effective, reducing cancer morbidity and mortality in the population depends on the successful delivery of mass screening. Today, screening for cancer may be achieved through the organized delivery of services, or unsystematically, by individual referral for screening at intervals which are not necessarily optimal or regularly spaced. Organized screening is distinguished from unsystematic screening primarily on the basis of how the offer of screening occurs--whether by invitation, issued from centralized population registers or coincidently, depending on individuals seeking screening on their own, or having providers initiate screening during visits for care for other reasons. This manuscript describes cancer screening in the USA, which for most Americans is unsystematic. While this model can achieve many of the goals of screening, these goals are achieved at a greater cost, less efficiently, and without the assurance of full participation of the entire, eligible population. In order to achieve the fullest potential of cancer screening in the most cost-effective manner, screening should be organized, with attention to monitoring the fullest performance of the programme from recruitment to follow-up.