Predicting mortality from cervical cancer after negative smear test results

Area of Science:

• Gynecologic Oncology
• Public Health Screening
• Cancer Epidemiology

Background:

• Cervical cancer screening programs aim to reduce mortality and incidence of invasive disease.
• Assessing the true protective effect of screening requires careful consideration of outcome measures.

Purpose of the Study:

• To evaluate the protection against cervical cancer death following two negative smear tests.
• To compare this protection with estimates for invasive cancer from the International Agency for Research on Cancer (IARC).

Main Methods:

• A model was developed using data from the British Columbia screening program.
• Risk of death from cervical cancer after negative smears was compared to unscreened women.
• Mortality and incidence of invasive cervical cancer were the primary outcomes.

Main Results:

• Protection against cervical cancer death was approximately 50% higher than protection against all invasive cancers in women with two negative smears.
• This difference is attributed to better prognosis for screen-detected versus clinically diagnosed cancers.
• Screening women aged 35-64 every five years could achieve a 90% reduction in cervical cancer mortality.

Conclusions:

• Screening intervals longer than three years are supported due to higher protection against mortality than disease.
• Longer intervals may mitigate high costs and negative side effects associated with frequent screening.