What is the difference between an HPV-DNA test and PreTect HPV-Proofer?

HPV DNA tests detect the presence of many HPV types but cannot give any information about the behaviour of the virus, whether it is normal or not. Many HPV DNA tests use a consensus strategy and will not distinguish between the different HPV types.

No currently commercial available HPV DNA tests can do direct typing as PreTect HPV-Proofer does.

PreTect HPV-Proofer detects only HPV viruses that have lost their replication and most of their “self control” and started to produce the oncogene proteins E6/E7 from the specific HPV types 16, 18, 31, 33 and 45.

HPV DNA tests will be positive in 20-30% of a normal female population. PreTect HPV-Proofer identifies only the 1-2% of women that are persistentlt positive with the same HPV type over e.g. 6 months.

Why are most HPV infections harmless?

HPV is a normal part of the microbiological flora of both women and men. Presence of HPV in the cervix is very common and usually harmless. The virus is mainly sexually transmitted and up to 80% of all women carry the virus once or more during their lifetime. In most cases the human immune system can defeat the virus in 1-2 weeks.

How is HPV testing regulated in the EU?

PreTect HPV-Proofer is a diagnostic test designed, developed and produced according to the EU in vitro diagnostic directive (98/79/EC of the European Parliament and of the Council of 27 October 1998 on in vitro diagnostic medical devices).

PreTect HPV-Proofer is CE marked since May 2003.

No HPV tests can be sold in EU without complying with these regulations.

HPV testing is new to me, is this only research?

Around 1974 the research on the connection between HPV and cervical cancer started (zur Hausen, H et al; Int. J. Cancer 13, 650-656, 1974). This research field is now 30 years old. In the 1980's the role of HPV in the development of cervical cancer was revealed and the effects of the oncogene proteins E6/E7 were described.

The 5 HPV types detected by PreTect HPV-Proofer produce the most carcinogenic substance ever discovered, the E6/E7 oncoproteins.

More than 1200 international articles have been published on E6/E7 and the risk of developing cervical cancer. The theoretical and practical foundation for PreTect HPV-Proofer is overwhelming.

More than 10 clinical studies on PreTect HPV-Proofer have been conducted together with the Norwegian National Hospital, the Norwegian Cancer Registry, and the Norwegian Radium Hospital in addition to research groups in Sweden, Denmark, Germany, Scotland and Italy.

All these clinical studies show clearly that PreTect HPV-Proofer identifies the production of the oncogene proteins E6/E7 from the five HPV types 16, 18, 31, 33 and 45. The clinical specificity is two-three times higher than HPV DNA methods detecting more than 20 HPV types.

Is it possible to use PreTect HPV-Proofer now?

Some people claim that diagnostic tests should go through randomised trials to establish the accuracy of the tests. This shows a lack of understanding of what a diagnostic test is compared to drugs or vaccines. Diagnostic tests have to document that they give correct answers to the question asked. Nobody will insist that a new blood pressure instrument should undergo studies lasting several years to assess whether high blood pressure measured with this instrument is dangerous? This perception is shared by international experts on infection medicine and also supported in evidence based medicine (Sackett et al, BMJ 1996; 312; 71-72): "To find out about the accuracy of a diagnostic test, we need to find proper cross sectional studies of patients clinically suspected of harbouring the relevant disorder, not a randomised trial."

More than 10 clinical studies have been performed on PreTect HPV-Proofer all showing that PreTect HPV-Proofer finds the relevant disorder, the expression of HPV oncogene E6/E7 proteins from the HPV types 16, 18, 31, 33 and 45. These studies have been conducted together with the Norwegian National Hospital, the Norwegian Cancer Registry, and the Norwegian Radium Hospital in addition to research groups in Sweden, Denmark, Germany, Scotland and Italy.

The clinical documentation stating the connection between the oncoproteins E6/E7 and the development of cervical cancer includes more than 1200 international publications giving a firm scientific foundation for PreTect HPV-Proofer.

What about the coming HPV vaccines, can they replace cytologi and HPV testing?

Today several HPV vaccines are under development. Several of these vaccines cover only HPV 6, 11, 16 and 18, i.e. only two of the most dominant 5 potentially dangerous HPV types.

As of today no clinical studies have started on other oncogenic HPV types.

If the present vaccine studies show good results, HPV vaccines will be commercially available in 5-10 years. Then young girls and boys have to be vaccinated before they have had any risk of being infected by HPV. Since the median age of cervical cancer today is 40-50 years, the measurable effect of the HPV vaccine will be visible in 20-30 years.

In most cervical carcinoma cases the HPV is integrated. It has been shown that integrated HPV DNA produce stabilised E6/E7 mRNA. It has also been shown that persistent oncogene expression may only happen when HPV is integrated. Loss of HPV replication may also be linked to HPV integration. However, nobody has proved that prophylactic or therapeutic vaccine remove integrated HPV. Therefore, prophylactic vaccine may only be tested properly when girls and boys without risk of having presence of HPV are vaccinated.

Other methods like cervical smears and HPV testing has to be performed in parallel with HPV vaccination for several decades..

DNA tests usually find more HPV types. Why is PreTect HPV-Proofer better with only five types?

The five HPV types offered by PreTect HPV-Proofer, i.e. HPV 16, 18, 31, 33 and 45, cover 97-99% of all HPV induced cervical cancer in Europe, North America and Australia.

HPV DNA tests have two main problems.

1) HPV DNA tests will miss 5-10% of cervical cancer samples due to integration of HPV DNA followed by deletion of parts of the genome. The virus has lost its possibility to reproduce and have lost most of its own regulation. Small and maybe undetectable quantities of HPV DNA may therefore be present, still producing large quantities of both E6/E7 mRNA and oncoproteins. Independent clinical studies shows that HPV DNA tests miss up to 10% of very good and representative samples from women with cervical cancer.

2) HPV DNA tests will identify 20-30% of normal women as positive. A lot of women will be told that they have a dangerous HPV virus in their cervix, but more than 90% will be false positive answers, i.e. there is no production of E6/E7 oncoproteins present. In a screening situation on a normal female population the specificity of an HPV DNA test will not be higher than 70-80%. International studies presented at the 21st International Papillomavirus Conference, 20-26 February, Mexico City, Mexico, concluded that for selected groups the specificity is below 40%. Several studies on PreTect HPV-Proofer show specificities above 90%.

Since numbers like specificity are dependent on different kinds of populations, comparing these numbers is very difficult. The only valid approach is to perform 2 independent tests on the same material taken from the same population in the same study. Clinical studies on PreTect HPV-Proofer together with HPV DNA tests have shown 2-3.5 times higher specificity for PreTect HPV-Proofer than the HPV DNA tests.

Recent results from a large clinical study in Oslo, Norway with follow up data over 2 years show that PreTect HPV-Proofer together with cytology have a sensitivity of 100% and a specificity above 97%.

Can HPV tests be used on other than ACSUS samples?

One problem with HPV DNA tests is that 20-30% of the women in a normal population will be positive. To avoid this very big problem some of the vendors recommend testing only on women older than 30 years of age or ASCUS samples.

The prevalence of HPV in women above 30 years of age is much lower than in women below 30 years of age. The consequence is that only 10-15% of the selected population will be positive with an HPV DNA test instead of 20-30%. However, this has nothing to do with the properties of the HPV DNA test, the underlying biology or any other clinical factor. This is just a consequence of population selection since younger women have a different sexual behaviour than older women. , More importantly women below 30 years of age also get cervical cancer today. Up to 3.5 times higher specificity than HPV-DNA tests has been discovered for PreTect HPV-Proofer detecting E6/E7 oncogene expression in women below 30 years of age. Another way to introduce HPV tests has been to limit testing to ASCUS samples. The goal has been to find women with no (or low) risk reducing their follow up rate. According to the FDA such an approach is not acceptable. An HPV DNA test will often be positive for up to 90% of the ASCUS samples (depending on the ASCUS definition, which varies around the world). Numerous studies have shown that 15-20% of the ASCUS samples have underlying serious dysplasia. Using a HPV DNA test on ASCUS samples will only confirm the ASCUS diagnosis and will not give the necessary clinical information to find these patients. PreTect HPV-Proofer finds 15-20% positive samples on ASCUS cases.

According to statistics from the Norwegian Cancer Registry 35% of women with cervical cancer had normal cytology only 2.2 years on average before cancer was discovered. Based on the vast amount of information in the more than 1200 international articles documenting the connection between E6/E7 oncoproteins and cervical cancer, it is obvious that PreTect HPV-Proofer would have found these women 5-15 years before cervical cancer developed.

What other factors than HPV affect the development of servere cervical dysplasia?

It is a well established scientific fact that HPV is a necessary factor for development of severe cervical dysplasia which may lead to cervical cancer. However, HPV in itself is not a sufficient factor for development of severe cervical dysplasia, i.e. the presence of HPV in the cervix does not imply that women will develop severe cervical dysplasia. This simple fact gives an absolute limitation for the clinical relevance of HPV DNA tests.

PreTect HPV-Proofer, however, does not detect HPV virions, but the expression of the carcinogenic E6/E7 proteins. More than 1200 international publications document that the production of the oncogenes E6/E7 is necessary for development of severe cervical dysplasia (e.g. Harald zur Hausen, Nature May 2002, vol 2, 342-350). HPV infections not producing E6/E7 oncoproteins will not develop to cervical cancer.

However, the literature is now indicating that in addition to being a necessary factor, the E6/E7 oncoproteins can also be a sufficient factor for the development of severe cervical dysplasia (e.g. AH Hall, Jvirol, 2003 May, 77(10):6066-9; K Butz, Oncogene, 2003 Sept 4;22(38):5938-45).

PreTect HPV-Proofer detects the necessary and probably sufficient factor for developing severe cervical dysplasia.