Effect of Pap Smear on the Long-term Survival of Cervical Cancer Patients: A Nationwide Population-based Cohort Study

Abstract

Objectives: This study aims to investigate the effect of cervical cancer screening by pap smear on the long-term survival of cervical cancer patients.Methods: We constructed a retrospective cohort of 14,903 women diagnosed with invasive cancer or carcinoma in situ (CIS) in 2008 and 2009 and followed up until December 31, 2019, by using individual-level data from three national databases of the Korean National Cancer Screening Program, the Korean Central Cancer Registry, and death certificates. Cox proportional-hazards regression was used to investigate the effect of cervical cancer screening on mortality.Results: A total of 12,987/14,867 patients (87.4%) were alive at the end of the follow-up period (median: 10.5 years). Screened patients had a 38% lower risk of cervical cancer death than never-screened patients (hazard ratio [HR]=0.62; 95% confidence interval [CI], 0.54–0.70). The risk of death from cervical cancer decreased by 59% and 35%, respectively, in screened patients with localized and regional stages. Further, a lower HR was observed in all age groups, especially women aged 50–59 years (HR=0.54; 95% CI, 0.42–0.69). The lowest HR for cervical cancer death was reported among patients screened within the past two years (HR=0.54; 95% CI=0.47–0.63), following which the HRs increased with increasing time intervals. Conclusions: Pap smear screening significantly reduces the risk of cervical cancer-specific death in Korean women across all cancer stages.