On an individual basis, each person certainly merits screening . Anything that creates an earlier diagnosis is to be encouraged. But questions inevitably have been raised about the expense, complexity and cost-effectiveness of screening programs for large groups of people. It has been especially difficult for some insurance companies to justify spending the substantial sums needed to diagnose a small number of cases.
    There has been some acceptance of the concept, though. Many health maintenance organizations and some small and large insurance companies have begun to promote and cover preventive screening services. In 1988, Medicare approved payment for routine mammograms because it has become increasingly clear that for certain age groups this simple procedure can detect breast cancers earlier and in a potentially more curable stage. A mammogram can provide a diagnosis about one year before a tumor could be detected otherwise.