Oral Contraceptives and Cervical Cancer-Reply

In Reply.  —Dr Celentano correctly points out that the negative associations found in our case-control study of oral contraceptives and invasive cervical cancer in Costa Rica and in his study in inner-city Baltimore¹ may reflect detection bias, rather than a truly protective effect. If oral contraceptive users are more likely to receive cervical smears than nonusers, they are more likely to be identified as having the disease before the invasive stage of cervical cancer and then to receive treatment. Thus, oral contraceptive users may be under-represented among cases of invasive cervical cancer, resulting in a spurious negative association.A lifetime history of one or more cervical smears is more common in the United States than in Costa Rica.² Despite the overall higher screening prevalence in the United States, Celentano et al reported that the enhanced screening of oral contraceptive users we found in Costa Rica also occurs in