Epidemiology of cervical cancer in Taiwan

Because the prevalence of several risk factors for cervical cancer, including sexual behavior, reproductive patterns, contraceptive use, and cigarette smoking, has changed significantly over time among Taiwanese women, it is of interest to analyze the impact of these trends on the incidence and mortality rates for this cancer during the decades between 1970 and 1990. The number of deaths from cervical cancer was obtained from the Taiwan Provincial Department of Health during the period from 1974 to 1992. Data of all incident cervical cancer cases from 1979 through 1990 obtained from the Taiwan Cancer Registry were also used for the analyses. The trends in the age-adjusted and age-specific rates were examined. Age, period, and cohort effects on the incidence and mortality rates were also examined, using age-period-cohort (APC) models. The age-adjusted mortality rate has been increasing since the 1970s, particularly in both the youngest group (20-29 years) and the oldest group (65 years and over). While the age-adjusted incidence rate decreased from 1979 to 1990, and decreases were apparent across all broad age groups, nevertheless, the incidence of adenocarcinoma was moderating during the same time period. The APC models disclosed a decreasing cohort effect for the mortality and incidence rates among women born after 1936. Decreasing incidence rates after menopause were more consistent with a hormonal effect than a cohort effect. Declining trends in cervical cancer incidence may be related to the screening practices which may have counteracted the increasing prevalence of several risk factors, although poor survival influenced the incidence/mortality differentials for cervical cancer. Continued surveillance is warranted; however, attention might be directed to the trends in cervical adenocarcinoma.