Cervical cancer is one of the most common cancers in Taiwan. In 1995, the Taiwan government was launched the cervical cancer screening program providing an annual pap smears test of women aged 30 or above. Due to this screening program, the cervical lesions could be diagnosed and treated early. The invasive cervical cancer incidence and mortality rate were decreased after screening program implemented, however, the incidence and mortality rate is still higher in elderly and higher than western countries. The aim of this study was to evaluate the association between pap smear test screening history and the risk of invasive cervical cancer at different age groups.
In this retrospective cohort study, women aged 36 years or above without cervical cancer history and alive in the end of 2009 were as study subjects. The pap smear screening history was retrospective to 2001-2009 and the incidence of cervical cancer was followed in 2010-2014. Data were obtained from the household registration database, cervical cancer screening registry database, and the cancer registry database. According to the screening history, subjects were classified into 8 groups, including A: regular screening; B: screening attendance in 2004-2006 and 2007-2009; C: screening attendance in 2004-2006, 2007-2009; D: screening attendance in 2007-2009; E: screening attendance in 2001-2004, 2004-2006; F: screening attendance in 2004-2006 sieve; G: screening attendance in 2001-2003; H: never screening. The cumulative incidence of 36-50 years, 51-65 years and over 66 years were estimated by Nelson-Aalen method and hazard ratios were estimated by Cox’s proportional hazards model
Our study results showed that in women over 66 years old never having pap screening test in 2001-2009 had the highest invasive cervical cancer incidence rate and hazard ratio. Women who had regular screening history, at least once in every three years, has the lowest risk of invasive cancer incidence. Moreover, the longer time interval since last pap test the greater the risk of invasive cervical cancer was increased, especially in women over 66 years. In conclusion, screening history pattern was associated with the risk of invasive cervical cancer in women aged 66 and older. And we need to further consider the feasibility and impact of whether the screening test stops at age 65 in Taiwan.