Cohort trends in incidence of cervical cancer in Denmark in relation to gonorrheal infection.

In England & Wales and in Scotland an association has been found between the cohort pattern in mortality for cervical cancer and gonorrheal infection, used as indicator of sexually transmitted diseases in general. An equivalent association could not be found in the United States. In Denmark a peak in gonorrheal infection was observed towards the end of World War II. The maximum level attained in Denmark was higher than reported from the other countries; in Copenhagen the attack rate was 3.3 times the rate for the rest of Denmark. Incidence data on cervical cancer in Denmark are available from 1943 to 1977. The 1918-27 birth cohort is assumed to be the one most heavily affected by the gonorrhea epidemic during the war. Incidence data accumulated over a broad age span show no general excess risk of cervical cancer for women born 1918-27, but the incidence is increased for this cohort 15-20 years after the gonorrheal infection. The cervical cancer rates are higher for women in Copenhagen than for all Danish women, but the excess risks for the affected cohorts are less systematic here. The limited size of the population in Copenhagen, migrations, and an intensive screening are possible explanations for the divergence between the results for all of Denmark and for Copenhagen. The study indicates an association in Denmark between sexually transmitted diseases and cervical cancer, and the study shows the importance of taking the risk-modifying effect of screening into account in studies of etiology for cervical cancer.