Rates of cervical cancer and deaths from the disease have decreased significantly over the past 30 years since the introduction of the Pap test, the main screening tool. It detects precursor lesions and can lead to early treatment and better long-term outcomes for women compared with treating the disease once symptoms arise.
"It is likely that much of the change seen in the incidence of cervical cancer in Canada is due to screening, but early and frequent (often annual) cervical screening is unnecessary: other countries have achieved similar outcomes with less frequent testing and starting screening at older ages," writes Dr. James Dickinson, Chair of the Task Force on Preventive Health Care's cervical screening working group and Professor of Family Medicine and Community Health Sciences at the University of Calgary, with coauthors.
The guidelines are an update to the Canadian Task Force on Preventive Health Care's guidelines issued in 1994. Aimed at physicians and policy-makers, the guidelines contain recommendations for cervical screening based on the latest available evidence as well as comparisons with screening in other countries.
- No routine screening for women under age 25, including sexually active women
- Routine screening every 3 years for women aged 25 to 69 years
- Ending screening for women aged 70 and over who have undergone adequate screening - that is, 3 successive negative Pap test results over the previous 10 years
- Screening for women over age 69 if they have not undergone adequate screening - that is, until 3 negative test results have been obtained.
Most countries outside North America recommend 3- or 5-year intervals for cervical cancer screening. The US task force recommends human papilloma virus (HPV) testing for women aged 30 years and older every 5 years, although this may increase testing and overtreatment. A comparison of screening recommendations for Canada, the US, United Kingdom, Ireland, Scotland, Australia and the Netherlands is included in the appendices.
"Practitioners should be aware of women's values, preferences and beliefs about screening and discuss these in the context of the potential benefits and harms of the screening process," write the authors.
Although HPV testing exists, it is not offered in all Canadian provinces and was not included in the guidelines. "The task force felt it premature to make a recommendation on the use of HPV testing in screening (either alone or in combination with Pap testing)," states Dr. Dickinson. "However, we will revisit this issue as new data become available."
In a related commentary, Dr. Janet Dollin, Department of Family Medicine, University of Ottawa writes about the role of HPV testing - which may have advantages compared with Pap testing, in her opinion - and the HPV vaccine in preventing cervical cancer.
"Pap testing is a single tool in an evolving toolkit to prevent cervical cancer," she writes. "Although the evidence needed to make evidence-based change is slow to come, we can envision a future where this cancer can either be prevented as a sexually transmitted viral infection or screened for less frequently with better tools."
In addition to the full guidelines, 1-page information pieces and screening algorithms are available for both physicians and patients on the task force's website.
The Canadian Task Force on Preventive Health Care is an independent body of 14 primary care and prevention experts. The task force has been established by the Public Health Agency of Canada to develop clinical practice guidelines that support primary care providers in delivering preventive health care.