OBJECTIVE: To evaluate the screening efficacy and importance of atypical squamous cells and atypical glandular cells in predicting subsequent cervical cancer risk.
METHODS: This national cohort study in Taiwan analyzed associations between Pap test screening frequency and findings in 1995–2000 and subsequent risk of squamous cell carcinoma and adenocarcinoma after 2002. Women aged 30 years or older in 1995 without a cervical cancer history were included. Multivariate-adjusted hazard ratios and their 95% confidence intervals (CIs) were assessed using Cox regression analysis.
RESULTS: During a total follow-up of 31,693,980 person-years in 2002–2008, 9,471 squamous cell carcinoma and 1,455 adenocarcinoma cases were newly diagnosed, resulting in 2,067 deaths. The risk of developing and dying from squamous cell carcinoma decreased significantly with increasing attendance frequency between 1995 and 2000 (all P values for trend <.001). Women who attended more than three screenings in 1995–2000 had 0.69-fold and 0.35-fold decrease in incidence and mortality of adenocarcinoma, respectively, compared with women who never attended any screenings. Abnormal cytologic findings were significant predictors of the incidence and mortality of cervical cancers. The adjusted hazard ratio (95% CI) of developing squamous cell carcinoma was 29.94 (22.83–39.25) for atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesions, and the adjusted hazard ratio (95% CI) of developing adenocarcinoma was 49.43 (36.49–66.97) for atypical glandular cells.
CONCLUSION: Significant reductions in cervical adenocarcinoma occurred in women who attend three or more annual screenings in 6 years. High-grade atypical squamous cells and atypical glandular cells are important predictors of subsequent adenocarcinoma and squamous cell carcinoma.
LEVEL OF EVIDENCE: II.
Screening frequency and atypia are important predictors of cervical cancer risk, and adenocarcinoma is significantly reduced in women who attended three or more screenings in 6 years.
Department of Obstetrics and Gynecology, College of Medicine and the Graduate Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, the Genomics Research Center, Academia Sinica, the School of Public Health, National Defense Medical Center, and the Health Promotion Administration, Ministry of Health and Welfare, Executive Yuan, Taipei, Taiwan.
Corresponding author: Chien-Jen Chen, ScD, Genomic Research Center, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 115, Taiwan; e-mail: firstname.lastname@example.org.
Supported by the Health Promotion Administration, Ministry of Health and Welfare, Executive Yuan, Taipei, Taiwan.
The authors thank Health Promotion Administration, Ministry of Health and Welfare, Executive Yuan, Taipei, Taiwan, for financial support of the project (Project number A1011113) and the members of the Taiwan Cervical Cancer Screening Task Force for management of data included in this analysis: Huang-Cheng Hsu, Ching-Hsun Ho, Hsiang-Yun Cheng, Yi-Wen Wang, Jian-Jhih Lin, I-Ling Chen, Ya-Chuan Chen, and Chiao-Ju Wu.
Financial Disclosure The authors did not report any potential conflicts of interest.