Test of Cure after treatment for HSIL (CIN2/3)

In women who have been treated for a high-grade squamous lesion (HSIL (CIN2/3)) the risk of recurrence and invasive cervical cancer remains elevated for 10–25 years[1][2][3][4][5][6] highlighting the importance of continued post-treatment surveillance to detect residual or recurrent disease. In Australia, the combination of LBC and testing for oncogenic HPV types (co-test) is used as a Test of Cure following treatment of HSIL (CIN2/3), based on the high negative predictive value of the co-test in detecting women at risk of recurrence. However, there has been some uncertainty regarding the length of time required for a women to be considered as cured and safe to return to the screening intervals recommended for the general population. 

Data published in the Report on monitoring activities of the National Cervical Screening Program (NCSP) Safety Monitoring Committee[7] demonstrated that, in women aged 20–69 previously treated for a high-grade CIN, the incidence of a subsequent high-grade lesion was very low, and there were no incidents of subsequent cervical cancer, following two consecutive occasions on which oncogenic HPV was not detected and LBC was reported negative (negative co-test). This holds true in more recent analyses of these data, which similarly show a low rate of subsequent high-grade lesions and no instances of cervical cancer following two consecutive negative co-tests.[8] These data support the effectiveness of two negative consecutive co-tests as Test of Cure,[7] as recommended in pre-renewal NCSP guidelines.

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Systematic review evidence

A systematic review was performed to identify studies evaluating the safety and effectiveness of discharging women previously treated for HSIL based on a negative co-test at 12 months versus 12 and 24 months. No randomised or pseudorandomised studies were found.

General literature review evidence

In the absence of any direct evidence from the systematic review, a general review of the literature was performed on the use of HPV testing and cytology in the follow-up of women treated for HSIL (CIN2/3).

Five recent articles were found [9][10][11][2][12] of which three were directly relevant, reporting 5-year risks of recurrent high grade CIN following one negative co-test and following two negative cotests. Katki et al estimated a lower 5-year risk of recurrent CIN2+ for two negative co-tests (1.5%) when compared with one negative co-test (2.4%) (p=0.8). However, the authors stated that estimates were based on small numbers and therefore subject to considerable uncertainty.[11] These findings were in agreement with reports from a Dutch study[10][2] of lower 5- year cumulative risks of CIN2+ and CIN3+ disease for a negative co-test at 6 and 24 months post treatment, when compared with a negative co-test at 6 months post treatment. In this study, the 5-year cumulative risk of CIN2+ was 1.0 (0.2–4.6) and of CIN3+ was 0.0 (0.0–2.9) following a negative co-test at 6 and 24 months. 

Based on the evidence from these two studies, women who have been treated for high-grade squamous lesions should have co-testing performed at 12 months after treatment and annually thereafter. When a woman undergoing annual co-testing has had a negative co-test on two consecutive occasions, she can return to routine screening.

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Flowchart 10.1. Test of Cure following treatment for high-grade squamous abnormalities