Two in five CIN2 biopsies were regraded on expert review

Design

Historical cohort with blinded expert pathology review

Population

437 women aged 23–40 under CIN2 surveillance, Aarhus 2000–2010

Primary outcome

CIN3 or worse during 28 months of follow-up

Effect

22.5% (expert CIN1/normal), 42.2% (CIN2), 64.3% (CIN3); expert CIN3 vs CIN2 aRR 1.37 (1.07–1.75)

This Danish cohort, published in April, took 437 women aged 23 to 40 under active surveillance for CIN2 between 2000 and 2010, and had three expert pathologists regrade the original biopsies with p16 staining. Only 59.7% stayed CIN2; 12.8% were upgraded to CIN3 and 27.5% downgraded to CIN1 or normal.

Over 28 months, 39.6% developed CIN3 or worse. Risk followed the expert grade: 22.5% after expert CIN1 or normal, 42.2% after CIN2 and 64.3% after CIN3. Compared with confirmed CIN2, expert CIN3 carried higher adjusted risk (aRR 1.37). High-grade index cytology and HPV16 kept risk high whatever the histology said.

Surveillance for CIN2 in young women is used to avoid excision and its preterm birth risk. This study suggests the diagnosis it rests on is less stable than assumed, so the decision is better built on cytology, HPV genotype and age as well as the biopsy.

• Before choosing surveillance for CIN2, check whether p16 staining or a second pathology opinion is available.
• Weigh high-grade cytology and HPV16 positivity as reasons to consider excision rather than surveillance.
• Consider age: risk after expert CIN3 was higher still in women aged 31 to 40.
• Keep follow-up colposcopy strict for anyone on surveillance, given four in ten progressed.
• Explain the preterm-birth trade-off of excision when counselling younger women.

Why it matters

Surveillance is only as safe as the diagnosis it rests on, and that diagnosis moved in two of five cases.

Don't overread it

This is one centre's historical cohort; it does not establish a new surveillance protocol.

The statistics, in plain English

An adjusted relative risk of 1.37 means women whose biopsy was really CIN3 were about a third more likely to progress than those with confirmed CIN2, after accounting for age, cytology and HPV type. The interval (1.07 to 1.75) excludes no difference, but is wide.

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