What are the guidelines for Pap (Papanicolaou) test screening in Canada?

Canadian Pap Test Screening Guidelines

Canadian women should begin cervical cancer screening at age 21 and undergo Pap testing every 3 years until age 69, with HPV co-testing every 5 years as an option for women aged 30-69. 1

Screening Initiation

• Start screening at age 21 years, regardless of sexual activity history. 2, 3, 4
• Women under age 21 should not be screened, even if sexually active, due to the extremely low incidence of cervical cancer in this age group (only 0.1% of all cases). 3
• The previous recommendation to screen within 3 years of sexual debut has been abandoned in favor of this fixed age threshold. 3

Age-Specific Screening Intervals

Women Aged 21-29 Years

• Screen every 3 years with Pap test alone. 2, 3, 4
• HPV testing should NOT be used in this age group for routine screening, as HPV infections are common and typically transient in younger women. 2, 4
• Liquid-based cytology allows for the 3-year interval; conventional Pap smears historically required annual screening until three consecutive normal results. 2

Women Aged 30-69 Years

• Preferred approach: Screen every 5 years with HPV and Pap co-testing. 2, 3, 4, 1
• Acceptable alternative: Screen every 3 years with Pap test alone. 2, 3, 1
• The longer 5-year interval with co-testing is justified by the increased sensitivity of combined HPV and cytology testing. 2, 3
• Canada has not widely implemented co-testing in organized programs, though it is recommended in some provinces. 5, 1

When to Stop Screening

• Women over age 65-70 years with adequate prior normal screening can discontinue screening. 2, 4
• Adequate screening is defined as ≥3 consecutive negative Pap tests OR ≥2 consecutive negative HPV and Pap co-tests within the last 10 years, with the most recent test within the last 5 years. 3
• Continue screening beyond age 70 for women who have never been screened, have inadequate screening history, or have had recent abnormal results. 6

Special Populations Requiring Modified Screening

Post-Hysterectomy

• Discontinue screening if the cervix was removed for benign reasons and there is no history of high-grade precancerous lesions or cervical cancer. 2, 3
• Women with a cervical cuff remaining may still require screening. 3

High-Risk Women

• Women with HIV, immunosuppression, history of cervical cancer, or in utero DES exposure require more frequent screening. 6, 2
• HIV-positive and immunocompromised women should be tested twice in the first year after diagnosis, then annually thereafter. 6
• These women should continue annual screening regardless of age. 6

Evidence Supporting 3-Year Intervals

• Screening every 3 years versus annually improves cancer detection by less than 5%, making annual screening inefficient. 2
• The 3-year interval substantially reduces false positives, unnecessary procedures, and healthcare costs while maintaining nearly equivalent cancer prevention. 3
• Extended intervals prevent overtreatment harms, which disproportionately affect younger women with transient HPV infections. 7

Canadian Context and Implementation

• Canada operates a combination of opportunistic and organized provincial/territorial screening programs, unlike the purely opportunistic U.S. system. 5
• Ontario and other provinces have developed organized screening programs with evidence-based invitation systems targeting women at appropriate intervals. 1
• Primary HPV testing (without cytology) is recommended but not yet implemented in some Canadian provinces. 5, 1
• Historical data from Manitoba showed 91% of women aged 35-64 had at least one test over 15 years, though 4% were overtested with multiple tests annually. 8

Common Pitfalls to Avoid

• Avoid screening women under age 21, as this leads to unnecessary procedures for transient HPV infections that would resolve spontaneously. 3, 7
• Avoid annual screening in average-risk women, as this increases costs and harms without meaningful benefit. 2, 7
• Do not use HPV testing in women aged 21-29 years, as high HPV prevalence in this age group leads to excessive false positives. 2, 4
• Ensure high-risk women are not under-screened by identifying those with immunosuppression, HIV, or previous abnormalities who require annual surveillance. 2
• Do not continue screening after hysterectomy with cervix removal for benign disease, as this provides no benefit. 2, 3

Patient Communication Considerations

• Canadian women prefer shorter screening intervals and earlier initiation than current evidence supports, creating potential resistance to guideline-adherent care. 9
• Adequate communication from healthcare providers is essential to explain why 3-5 year intervals are safe and evidence-based. 9
• Women should receive written documentation confirming whether a Pap test was performed, as self-reports are often inaccurate. 2, 4