ASSOCIATION OF SCHISTOSOMIASIS WITH CERVICAL-CANCER - DETECTING BIAS IN CLINICAL-STUDIES

To investigate if Schistosoma haematobium infection increases the obse rved frequency of cervical cancer, data from literature were analysed in meta-analysis fashion, Results reveal that cervical cancer is stati stically significantly less frequent in the presence of S. haematobium infection. A protective effect might be inferred; however, underlying bias in data collection and/or analysis is suspected, An approach to detecting bias is given, consisting of: (a) carefully stating and asse ssing the several components of the scientific method and; (b) identif ying and contrasting the populations hypothesised and sampled, The app roach is illustrated by searching for bias in the schistosomiasis-and- cancer reports. Sampling discrepancies were detected in patient geogra phy, ages, and states of health, and suspected in disease prevalence s ampled and disease prevalence reported, The conclusion is reached that effects of bias in the original studies preclude inference of a ''pro tective'' effect of S. haematobium infection against cervical cancer.