Extending cervical screening beyond 5 years for some women is safe, finds study

This is a first step towards risk based screening, say researchers.

Extending the cervical cancer screening interval beyond five years for women aged 40 and older who test negative for human papilloma virus (HPV) is safe, say researchers from the Netherlands in The BMJ this week.

Extending screening for women who test positive for HPV, however, is not recommended.

Trials have shown that screening for HPV leads to earlier detection of abnormal cells (known as cervical intraepithelial neoplasia or CIN) than cytology (smear) testing - and offers better protection against cervical cancer.

CIN is divided into grades - CIN1, 2 or 3. The higher the number, the more of the cervix is affected by abnormal cells.

Currently in the UK, women aged between 25 and 49 are invited for screening every three years, and up to the age of 64, every five years.

In the Netherlands, screening intervals for HPV negative women aged at least 40 years will be increased from five to 10 years in 2017.

But evidence on the safety of screening intervals beyond five years is limited. So a team of researchers based in the Netherlands decided to assess the safety of extending screening intervals beyond five years.

They base their findings on 14 year follow-up data from over 43,000 women aged 29-61 years who took part in a large trial of three cervical screening rounds (each round done every five years).

Women were randomly assigned to receive both HPV and cytology testing (intervention) or cytology testing only (control) and were managed according to their test results.

The data show that HPV negative women aged at least 40 have a very low risk of CIN3+ (the highest grade of abnormal cells) in the long term, "indicating that extension of the current screening interval in the Netherlands is justifiable," say the authors.

But they stress that for HPV positive women, the long term risk of CIN3+ is too high to support extending screening beyond five years.

The use of the HPV test result and age to define the year of next screen is a first step towards tailoring screening to individual risks - and could improve screening efficiency and eventually provide optimal prevention for all women, they write.

However, they point out that data on cervical cancer risk are inconclusive, and "therefore it remains important to closely monitor the number of interval cancers observed under the new HPV based screening programme."

Article: Safety of extending screening intervals beyond five years in cervical screening programmes with testing for high risk human papillomavirus: 14 year follow-up of population based randomised cohort in the Netherlands, Maaike G Dijkstra, Marjolein van Zummeren, Lawrence Rozendaal, Folkert J van Kemenade, Theo J M Helmerhorst, Peter J F Snijders, Chris J L M Meijer, Johannes Berkhof, The BMJ, doi: 10.1136/bmj.i4924, published 4 October 2016.