Date Published: October 24, 2017
Publisher: Public Library of Science
Author(s): Jiangrong Wang, Bengt Andrae, Karin Sundström, Alexander Ploner, Peter Ström, K. Miriam Elfström, Joakim Dillner, Pär Sparén, Wei Zheng
Abstract: BackgroundThe relatively high incidence of cervical cancer in women at older ages is a continuing concern in countries with long-established cervical screening. Controversy remains on when and how to cease screening. Existing population-based studies on the effectiveness of cervical screening at older ages have not considered women’s screening history. We performed a nationwide cohort study to investigate the incidence of cervical cancer after age 60 years and its association with cervical screening at age 61–65, stratified by screening history at age 51–60.Methods and findingsUsing the Total Population Register, we identified 569,132 women born between 1 January 1919 and 31 December 1945, resident in Sweden since age 51. Women’s cytological screening records, cervical cancer occurrence, and FIGO stage (for those diagnosed with cancer) were retrieved from national registers and medical charts. We calculated the cumulative incidence of cervical cancer from age 61 to age 80 using a survival function considering competing risk, and estimated the hazard ratio (HR) of cervical cancer in relation to screening status at age 61–65 from Cox models, adjusted for birth cohort and level of education, conditioning on women’s screening history in their 50s. In women unscreened in their 50s, the cumulative incidence up to age 80 was 5.0 per 1,000 women, and screening at age 61–65 was associated with a lower risk for cervical cancer (HR = 0.42, 95% CI 0.24–0.72), corresponding to a decrease of 3.3 cancer cases per 1,000 women. A higher cumulative incidence and similarly statistically significant risk decrease was seen for women with abnormal smears in their 50s. In women adequately or inadequately screened with only normal results between age 51 and age 60, the cumulative incidence of cervical cancer from age 61 to 80 was 1.6 and 2.5 per 1,000 women, respectively, and further screening at age 61–65 was not associated with statistically significant decreases of cervical cancer risk up to age 80, but with fewer cancer cases of advanced stages at age 61–65. Adjustment for potential lifestyle confounders was limited.ConclusionsIn this study, cervical screening with cytology at age 61–65 was associated with a statistically significant reduction of subsequent cervical cancer risk for women who were unscreened, or screened with abnormalities, in their 50s. In women screened with normal results in their 50s, the risk for future cancer was not sizeable, and the risk reduction associated with continued screening appeared limited. These findings should inform the current debate regarding age and criteria to discontinue cervical screening.
Partial Text: The relatively higher incidence of cervical cancer in women older than 60 years as compared to women at age 45–60 years has become a concern in countries with long-established cervical screening [1,2]. The older aged cases still account for more than one-third of the annual cervical cancer case load, and are also found at more advanced stages [3,4]. Cervical screening, which has been mainly provided to women up to age 50–60 [5–8], is being extended to the age of 60–65 or 70 in countries facing high incidence of cervical cancer in older women [5,9,10]. However, the age at which to cease cervical screening, and with which criteria, remains controversial, as the existing evidence is insufficient.