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Lookup NU author(s): Dr Claire Rees,
Dr Petra Sevcikova,
Professor Allyson Pollock
This is the authors' accepted manuscript of an article that has been published in its final definitive form by Sage Publications Ltd., 2020.
For re-use rights please refer to the publisher's terms and conditions.
We do not know how well HPV vaccination will protect against cervical cancer. Trials have not focused on the outcome of cervical cancer because they had too few participants and didn’t follow them up for long enough: cervical cancer may take decades to develop.Published numbers from RCTs (randomized controlled trials) may overstate efficacy because: a) testing occurred too frequently in the trials when, in real world settings, lesions may regress spontaneously; b) trials used composite surrogate outcomes, some of which, such as HPV-infection and CIN1, occur more frequently than others and are very unlikely to progress to cancer; and c) subgroups were overanalyzed.The trial populations have limited relevance and validity for real world settings: for example, women in the trials were older than the target population; we don’t have enough data on the benefits in women who may have been exposed to HPV before they were vaccinated and who do not know their HPV status.We do not have enough data on the impact of the vaccine on CIN3, which is more likely than CIN 1 and 2 to progress to cervical cancer. We also have less data on the impact on cervical disease due to any HPV type rather than just lesions due to HPV 16 and 18.Women should still attend regular cervical screening because efficacy in preventing cervical pre-cursors is <100% and there are more oncogenic types than those covered by the vaccines. We have good evidence that cervical screening significantly reduces the risk of cervical cancer in women regardless of whether they have been vaccinated. The number of new cancers and deaths have fallen markedly such that cervical cancer now accounts for only 1% of cancer deaths in women in the UK (854 deaths in 2016).Information from the trials can tell us what happens between 5-9 years after vaccination, but we do not know if protection wanes after this time.A recent observational study provides some evidence of efficacy against CIN3+ in girls vaccinated before sexual debut. Ongoing observational studies may tell us about the long term effect on rates of cervical cancer, but it will take many years before we have the evidence.
Author(s): Rees C, Brhlikova P, Pollock AM
Publication type: Article
Publication status: Published
Journal: Journal of the Royal Society of Medicine
Print publication date: 01/02/2020
Online publication date: 21/01/2020
Acceptance date: 17/12/2019
Date deposited: 18/12/2019
ISSN (print): 0141-0768
ISSN (electronic): 1758-1095
Publisher: Sage Publications Ltd.
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