Cervical Screening Follow-up
In 2016, over 87% (3,600) of Ontario women age 21 to 69 who had a high-grade abnormal result on a Pap test had a follow-up with a diagnostic procedure or definitive treatment within 6 months. Follow-up was 90% for high-grade squamous intraepithelial lesion (HSIL), 85% for atypical squamous cells that cannot exclude HSIL (ASC-H), and 77% for atypical glandular cells (AGC). Despite notable regional variation, an overall increase was observed in follow-up, from 83% in 2013 to 87% in 2016. Three diagnoses (HSIL, ASC-H and AGC) made up 99% of all high-grade abnormal Pap test results.
Measure: Follow-up: percentage of Ontario screen-eligible women, age 21 to 69, with a high-grade cervical dysplasia on a Pap test who underwent colposcopy or definitive treatment within 6 months of the high-grade abnormal screen date
As of this Report:
What is cervical screening?
- Cancer screening is testing for people who may be at risk of getting cancer, but who have no symptoms and generally feel fine. It is not meant to diagnose cancer. Instead, it helps determine which people are more likely to develop cancer in the future. Ontario operates organized screening programs for 3 types of cancer: breast, cervical and colorectal.
- The purpose of cervical screening is to prevent cervical cancer by identifying pre-cancerous changes in the cells of the cervix. In Ontario, the cervical screening test currently in use is the Pap test. Changes to the cervical screening test are under consideration.
- Cancer Care Ontario updated its cervical screening guidance in 2012. It now recommends cervical screening every 3 years for women age 21 to 69 who are, or who have ever been, sexually active. Women can stop screening at age 70 if they have had 3 or more normal tests within the previous 10 years .
- Changes in the cervix that lead to cancer are called precursor or pre-cancerous lesions, and they usually develop slowly over many years. Screening is the best way to find the early cell changes that might lead to cervical cancer because those early cell changes do not have any symptoms.
- Colposcopy is an exam done by a specially trained doctor (a colposcopist) after a woman has an abnormal screening test result. It is the next step in the investigation of most abnormal screening test results. The colposcopist may remove or take a biopsy of abnormal-looking tissues, make a diagnosis and (if necessary) develop a treatment plan. After the diagnostic process is complete, a woman with a precursor lesion requiring treatment may undergo a loop electrical excision procedure, laser therapy or cold knife cone biopsy . Treating precursor lesions can prevent cervical cancer from developing.
What do the results show?
Most Ontario women with a high-grade abnormal Pap test are receiving timely follow-up within 6 months (Figure 1).
- The proportion of Ontario women receiving a follow-up within 6 months of a high-grade abnormal Pap test result has improved in recent years, increasing from 83% in 2013 to 87% in 2016. For women with a high-grade abnormal Pap test, a higher rate of follow-up and diagnostic testing in colposcopy is needed.
- In 2016, the Local Health Integration Networks (LHINs) with the highest rate of follow-up were Mississauga Halton and North Simcoe Muskoka (both 91%). North West LHIN had the lowest rate (63%).
- Most LHINs made improvements in their rate of follow-up from 2013 to 2016. The Erie St. Clair LHIN was most successful, with an increase in follow-up of 11 percentage points. A few LHINs showed a decrease in follow-up during this period, the greatest of which occurred in the South East LHIN (5 percentage points).
- The number of abnormal cervical screening tests in Ontario has increased from almost 4,000 women in 2013 to 4,200 women in 2016. Among the most frequent abnormal cell types found on Pap tests, follow-up was highest for women with HSIL (90% in 2016) and lowest for women with AGC (77% in 2016). A similar pattern can be seen in previous years (Figure 3). Of all abnormal cell types, including those with low incidence, adenocarcinoma in situ (20 people in 2015) had the highest follow-up rate (95%).
- Information on follow-up rates is limited to Ontario data and does not account for participants who may have secured follow-up outside of Ontario.
Follow-up of high-grade abnormal Pap test results varies by age group (Figure 2).
- Follow-up of abnormal cervical screening results varied by age group. In 2016, follow-up within 6 months of an abnormal Pap test result was highest in women age 40 to 49 (89%) and lowest in women age 60 to 69 (82%).
Why is this important to Ontarians?
Appropriate and timely follow-up of abnormal screening results are essential for screening.
- Human papillomavirus (HPV) infections can cause abnormal cell changes in the cervix and abnormal screening test results. Only abnormal cell changes caused by cancer-causing types of HPV put a woman at risk of getting cervical cancer. While there are over 100 different types of HPV, cervical cancer is mainly caused by the 12 to 15 high risk types of HPV infections. When a high risk-infection persists (does not go away) for a number of years, it can lead to cervical cancer unless the abnormal cells caused by the infection are found early and treated. HPV is passed from one person to another through intimate (i.e., skin-to-skin) sexual contact. HPV infections are common, and up to 80% of sexually active men and women will have an HPV infection in their lifetime [3, 4].
- An abnormal screening test result does not mean that a woman has cervical cancer, but it does mean that more follow-up and diagnostic testing are needed.
- The first cohort in Ontario’s school-based HPV vaccination program reached screen-eligible age in 2016. As the proportion of HPV-vaccinated women in the screening cohort increases, Cancer Care Ontario will continue to explore implications for screening practices related to this shift. HPV-vaccinated women should still be screened according to the current recommendations.
- The HPV vaccine does not protect against all cancer-causing HPV types, and it does not eliminate HPV infections acquired before a woman is vaccinated. Only screening can protect against cervical cancer that is caused by an earlier infection.
- Timely follow-up of abnormalities found through cervical screening is necessary for the reduction of cervical cancer incidence (i.e., new cancer cases) and mortality (i.e., deaths) [5–7].
- Cervical cancer incidence has decreased by as much as 80% where screening quality, access and follow-up are high .
- Cancer Care Ontario is developing evidence-informed strategies to increase access, align processes, improve practices and enhance the quality of colposcopy services in the province. The Ontario Cervical Screening Program (OCSP), Ontario’s organized cervical cancer screening program, recently released evidence-based clinical guidance for the delivery of colposcopy services in Ontario . Next steps include working with regional partners to encourage implementation of this guidance.
- An integrated Primary Care Screening Activity Report (PC SAR) for all 3 screening programs (breast, cervical and colorectal) has been developed. This tool allows physicians in a patient enrolment model practice to see the complete screening status for each of their enrolled age-eligible patients, including those who are due for screening and follow-up.
- The OCSP correspondence program began in the fall of 2013. Eligible women are sent letters inviting them to get screened and letters advising them of next steps based on their test results.