HPV and Cervical Cancer
To Vaccinate or Not
Cervical cancer is the second most common cancer in women under 35 in the UK. It claims 1,300 lives each year, compared to 270,000 deaths worldwide. It is because it is a potentially preventable and, if diagnosed early, eminently curable cancer that cervical screening was introduced. The screening programme has, for more than one reason, failed some women who end up developing cancer. Cervical screening programmes involve women attending their doctors' clinics regularly for cervical smears.
Deaths from cervical cancer are a crude measure and only tell a small part of the story of the effect of both the treated cancers and pre-cancers (CIN and VIN) on society in terms of time, money and psychological impact.
Does Cervical Screening work?
The screening programme for cervical cancer, compared to any other cancer screening, has been successful because the cervix is accessible; there are recognized pre-cancerous stages; the test can be reproduced; treatment of the pre-cancer can prevent progress to cancer and it is cost effective. More importantly is the fact that both the screening and the management of the abnormal result is acceptable to women. Despite these advantages and a well-run screening programme, women still die of cervical cancer and there is still a high level of morbidity, more often psychological than physical, arising from the diagnosis of an abnormal smear. Some of the changes on the smear being as far removed from cancer as a normal smear is. It is also a sad fact of life that those most likely to develop cancer never enroll or take full advantage of the screening programme. The current frequency of NHS screening is in part economic. It is important to appreciate that no screening test, by definition, is 100% effective, that is, there will always be false positive as well as false negative results.
Human Papilloma Virus
The association between the ubiquitous Human Papilloma Virus (HPV) and the common squamous form (95%) of cervical cancer as well as the development of genital warts has long been well documented. Around 100 different strains have been identified. Over 70% of cervical cancers are caused by two HPV strains, namely Type 16 and 18. The other 30% are caused by approximately 11 other cancer-causing strains. The time frame from HPV infection to developing cancer is typically over 10 years although there are a few women who are unfortunate enough to have more rapid progression. HPV is also implicated in precancerous vulval changes and vulval cancer. It is also true that a Nun who has an exclusive relationship with God is unlikely to develop squamous cervical cancer, thus emphasizing the role of sexual intercourse or genital contact in its etiology.
Of interest is the fact that not all women who carry the virus develop pre-cancer or cancer and some women who get infected do not express the virus. A simple way of understanding the behavior of this virus may be to compare it to the Herpes Simplex virus, which causes cold sores. Most of us are infected with virus in early childhood but not everyone suffers from recurrent cold sores. The expression of the virus as cold sores depends on a person's antibody status. Those with a strong antibody response will either eliminate the virus or prevent its reactivation and those with a poor antibody response will have recurrent cold sores.
Once the association between HPV and cervical cancer was appreciated, research became more focused on prevention. If a way could be found to prevent infection or treat infection before it triggers the slow process that leads to cancer, then this could decrease the reliability on an imperfect screening programme. Vaccination, in a manner similar to how Rubella is prevented, became the obvious way.
Several problems arose. Firstly, the diversity of the strains of cancer causing HPV meant that the vaccine should prevent infection by all or most of the important strains. Second, the vaccination programme should commence before infection occurs, which means before any sexual activity. The moral argument for this continues to be had because of the association with sexual activity. Parents already allow their children to be immunized against Rubella and the argument is not dissimilar. Thirdly, besides the economic arguments, there are logistic and scientific issues such as whether immunity will be lifelong to be settled.
Men appear to have escaped serious consequences of HPV infections apart from unsightly genital warts, but act as a reservoir and vector for transmission to those they most cherish. Their importance in any vaccination programme cannot therefore be overlooked, although in the final analysis, it may all be down to health economics and whether genital warts are worth preventing? The case not to vaccinate boys in the prevention of cancer can be made stronger if the vaccine can have universal up take and immunity can be as close to 100% as has been shown in trials.
The cervical screening programme still has a vitally important role, although if most cancers can be prevented by vaccination it may cease to be cost effective in generations to come as the cost for preventing each cancer rises.
The New Strategy for Prevention - Vaccination
The realistic goal of the available and licensed HPV vaccine, Gardasil, is prevention of up to 75% of cervical cancers and 90% of genital warts. It is recommended that it be given to females between the ages of 9 and 26 and boys between the ages of 9 and 15. The reason for recommending its use in girls and young women who are sexually active and may already have been infected is that it is unlikely that they may have been infected by all strains of HPV against which the vaccine is active.
Gardasil is a suspension containing highly purified Virus Like Particles (VLP) administered as intramuscular injections in three doses over a six-month period. This stimulates the body's immune system to produce antibodies to fight any future infection with the strains of HPV 6, 11, 16 and 18. It is not yet certain whether future booster doses will be necessary to maintain immunity.
The side effects from the vaccine are common to every other vaccine and include, local reaction, fever and very rarely, hypersensitivity.
The NHS Position
The Department of Health confirmed in an email that they are awaiting the advice of the Joint Committee on Vaccination and Immunization (JCVI) on whether a vaccination programme should be established. In the meantime more and more adolescents get infected. It is estimated that 6 million new infections occur in the USA every year, 70% of which are in the 15 to 24 year olds. The return on the investment for the nation is long-term and will be seen in the decreasing need for expensive colposcopy clinics. (see important update)
The vaccine has been available in the USA and other countries since 2005 and early this year the German government announced that it would be offered to ALL girls for free as a matter of course.
Until guidance and funding becomes available from the government, it will be up to individual parents and young people, who are on the whole ignorant of the association of HPV with cancer, to decide on whether or not to vaccinate their children, both girls and boys. Finding a medical practitioner able to counsel and supervise the immunization may be a challenge.
Self-preservation is a basic human instinct but, although it is a relatively small investment in a child's future, it will be those with disposable income and awareness who benefit from this innovation! The vaccinated child will continue to have regular smears, which are almost always going to be normal thus avoiding multiple visits to a colposcopy clinic and more importantly drastically reduce their lifetime chances of having cervical cancer. The chances of contracting genital warts will also be greatly reduced.
Education on safe sex to make young people aware of the other dangerous infections that still pose a threat remains vital. Crucially, acceptance of the vaccine by parents on behalf of their children will depend on their understanding of a preventable condition associated with sexual activity.
Your Next Step
The logical next step would be to discuss this with your GP who will most probably confirm the NHS position. There are private clinics offering the vaccine throughout the country. Alternatively, you can contact us at the Women's Health Clinic.