THE PRACTICE OF CAUSAL INFERENCE IN CANCER-EPIDEMIOLOGY

Causal inference is an important link between the practice of cancer e pidemiology and effective cancer prevention, Although many papers and epidemiology textbooks have vigorously debated theoretical issues in c ausal inference, almost no attention has been paid to the issue of how causal inference is practiced, In this paper, we review two series of review papers published between 1985 and 1994 to find answers to the following questions: which studies and prior review papers were cited, which causal criteria were used, and what causal conclusions and publ ic health recommendations ensued, Fourteen published reviews on alcoho l and breast cancer and 6 published reviews on vasectomy and prostate cancer were examined, For both series of reviews, nearly all available published studies were cited except for ecological studies and prior reviews, Sources of causal criteria were often not provided, When they appeared, all citations were either the 1964 Surgeon General's report or works of Austin Bradford Hill, Reviews often excluded and sometime s altered criteria without giving reasons for these changes, The crite ria of consistency and strength of association were almost always used accompanied by dose-response and biological plausibility in a majorit y of reviews, The criterion of temporality, considered by many methodo logists to be a necessary causal condition, was infrequently used, Con founding and bias were often added considerations. Public health recom mendations were not discussed in nearly one-half of the reviews.