In my last blog I discussed the possibility of cervical cancer becoming a rare disease in certain countries. Part of this remarkable happening has been the introduction of the HPV vaccine, in certain countries up to 80% of the eligible adolescence population have been vaccinated. However there have been a number of developments both good and bad that are interfering and may well derail and even lead to suspension of some of the vaccination programs.
The first of these problems relates to a worldwide shortage of the HPV vaccine. Last year (2018) both UNICEF and the WHO highlighted in a report that this shortage was primarily due to increased vaccine demand and the inability of the drug companies to satisfy the demand. The shortage is projected to last for several years. Many questions now arise and these were highlighted in an address to the British Colposcopy Society 2019 annual meeting in Bournemouth earlier this year by Professor Douglas Lowy of the National Cancer Institute in the United States, who helped develop the HPV vaccine. He asked whether during this period of shortage there should be policy changes in the industrialised world concerning adding gender neutral vaccinations to the vaccination program or increasing the age range for recommending vaccination.
These shortages are very disheartening when we now see the benefits of vaccination. Within the last few months, results from the Scottish immunisation programme show how dramatic a fall there has been, not only in HPV infections, but more importantly in the rate of severe precancers whose elimination reduces the risk of developing cervical cancer. For example, the prevalence of the high-risk HPV virus type 16 and 18 has fallen from 30% to 4% in just a few years, mainly due to vaccination and the herd immunity that it creates. However, the most important fall has been in the frequency of the high grade precancer with an unbelievable 90% decline. It is of interest that this fall has been more obvious in women from deprived areas who will generally have an inherently higher rate of cervical cancer.
Another major concern is in relation to the implementation of the HPV screening program in the UK. Dr Alejandra Castañon, writing in the Journal of Medical Screening a few months ago, highlighted the consequences of delay, “a one-year delay in the implementation of HPV screening would miss the opportunity to prevent 581 cervical cancers and lead to a loss of 1,595 QALY (quality of life years) with a monetary value of £32 million (at £20,000 per QALY)”. The sobering thought is that for every week that primary HPV screening is delayed, an extra 10 women will get some form of cervical cancer in England.
Notwithstanding these delays in implementation of the vaccine, we have seen recent developments in screening for cervical cancer which show exactly how superior HPV testing is when compared with cytology. Two big studies following over a million women tested with both HPV and cytology over many years have shown that there is a significant increase in the number of lives saved by using just HPV screening when compared with those saved by cytology.
A new self-screening test is also in the early stages and looks promising, although it’s 3-5 years away. I’ll be discussing this developing news in a blog post in the near future.
And finally, the smear test is still of some benefit, such as when used on women who test HPV positive. The HPV test tells us that there has been HPV exposure at some time, but in only about 1 in 6 cases will it indicate the actual presence of an abnormality. The smear test will then confirm the presence of this abnormality. New data suggests that biomarkers may also be of benefit in identifying those with HPV. If HPV is to be used as a screening test in the future, women will need to be tested only every 5 to 6 years. Women who have been vaccinated may need only 3 or 4 HPV tests in their adult life – an amazing thought to those of us who have worked in this area for 5+ decades.