Japanese Journal of Clinical Oncology Advance Access originally published online on July 14, 2006
Japanese Journal of Clinical Oncology 2006 36(8):511-518; doi:10.1093/jjco/hyl060
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© 2006 Foundation for Promotion of Cancer Research
Effectiveness of Cervical Cancer Screening Over Cervical Cancer Mortality Among Japanese Women
1 Department of Public Health, Sapporo Medical University School of Medicine, Sapporo, 2 Department of Clinical Epidemiology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Kita-kyushu, Fukuoka, 3 Fukuoka Institute of Occupational Health, Fukuoka, 4 Department of Health Promotion and Preventive Medicine, Nagoya City University Graduate School of Medical Sciences, Nagoya and 5 Department of Preventive Medicine/Biostatistics and Medical Decision Making, Nagoya University Graduate School of Medicine, Nagoya, Japan
For reprints and all correspondence: M. M. H. Khan, Department of Public Health, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan; E-mail: khan{at}sapmed.ac.jp
Received March 24, 2006; accepted May 2, 2006
Background: Various studies have revealed that cervical cancer (CC) screening significantly reduces both CC incidence and mortality in developed countries. Although Japan introduced a nationwide government funded annual CC screening for the women aged 30+ in 1982, the effectiveness of CC screening on CC mortality has not yet been evaluated by any prospective cohort study. Therefore, the present study evaluated the association of CC mortality with self-reported CC screening and some other factors by a nationwide cohort study.
Methods: Baseline survey of the Japan Collaborative Cohort Study for the enrollment of subjects was completed during 1988–90 and followed until 2003. This study only analyzed 63 541 women, aged 30–79 years, who were free from any cancer history at enrollment.
Results: During the follow-up period, 38 CC deaths were identified. The mean age at mortality was 67.0 years, with a mortality rate of 4.2 per 100 000 person-years. Participation rate in CC screening was 46.9%. Age-adjusted Cox model indicated significantly lower CC mortality [hazard ratio (HR) = 0.30, 95% confidence interval (CI) = 0.12–0.74] due to CC screening. Protectiveness remained almost the same (HR = 0.30, 95% CI = 0.12–0.76) when adjusted for age, body mass index and number of deliveries. The results also revealed that CC screening could reduce at least 50% of CC deaths even after excluding the effect of possible self-selection bias.
Conclusions: CC screening in Japan may reduce CC mortality significantly for women aged 30–79 years. However, further studies with more CC deaths and increased statistical power are needed to validate the findings.
Key Words: cervical cancer mortality • Pap smear test • cohort study • Japan