Why Do Women Get Cervical Cancer in an Organized Screening Program in Canada?

The aim of the study was to determine factors associated with the development of cervical malignancy among women participating in an organized cervical screening program.

A population-based retrospective cohort study was performed examining the screening histories 2 to 10 years before diagnosis of invasive cancer in Ontario women between 2011 and 2014.

A total of 2,002 cases of cervical cancer were identified; 1,358 (68%) were squamous cell carcinomas and 644 (32%) were adenocarcinomas. The mean age at the time of diagnosis was 50.3 years. More than 60% of the cohort had at least 1 cytology test within 2 to 10 years of their diagnosis. Of the women having a cytology result 24 to 36 months before diagnosis, 69% had a normal cytology whereas only 7% had a high-grade cytology result. Stage of cancer was most advanced in women who did not have cytology in the 2 to 10 years before their diagnosis. On multivariate regression, those with cervical cancer who were less likely to have undergone screening include older age, advanced stage, lower income, not having a family physician, and those diagnosed with adenocarcinoma.

Although nonparticipation in screening is the greatest factor associated with cervical cancer diagnosis, failure of cervical cytology to detect cytologic abnormalities in women 2 to 3 and 3 to 5 years before diagnosis is of concern. Efforts must be directed to recruitment of women for screening as well as improving the sensitivity of screening tests to detect existing abnormalities.