BIASED COMPARISONS OF LUNG-CANCER SURVIVAL ACROSS GEOGRAPHIC AREAS - EFFECTS OF STAGE BIAS

This report illustrates bias that may affect comparative analyses canc er survival across geographic areas and describes how it limits the co nclusions that can be drawn from such data. Despite the application of a standardized procedure for assigning tumor stage, patients from dif ferent areas who are assigned the same stage category may not be homog eneous with respect to extent of disease, if staging is accomplished m ore aggressively in one group than in another. Stage-specific comparis ons of survival may be biased as a result. Cancer sites for which a la rge majority of patients are treated surgically may be less susceptibl e to stage bias.