The decline in the mortality rates of cervical cancer and a plausible explanation in Shandong, China

Abstract

The aim of the present study is to describe the temporal trends in mortality rates of cervical cancer in Shandong Province, China, and to elucidate their likely explanations. Three retrospective surveys of all causes of death in 1970-1974, 1985-1989 and 1990-1992 in Shandong were carried out. An age-period-cohort analysis based on similar survey data from Qixia, a county in Shandong, from 1970 to 1994 was performed. A correlation analysis between prevalence of syphilis and cervical cancer mortality rates three decades later was conducted. A cross-sectional survey of risk factors for cervical cancer was conducted in 1991 in one city and 12 villages in the province. A marked decline in cervical cancer mortality rates was observed from 1970 to 1992 and in successive birth cohorts from 1892 to 1927, and rates remained relatively constant in subsequent birth cohorts through that of 1952. The decline in these rates was strongly correlated with a decline in positive serological tests for syphilis 32 years previously. The percentages of women with selected risk factors were lower in younger women (30-54 years) than in older women (55-69 years) in both cities and rural areas. These trends are compatible with a decrease in risk of exposure to sexually transmitted factors at an early age after the founding of the People's Republic of China in 1949, and a decline in lifetime duration of exposure to possible co-factors in successive birth cohorts who reached sexual maturity before that time.