Screening for cervical cancer is traditionally carried out by cytology of a cervical smear.
Over the next 5 years or so, this will change worldwide to primary screening with Human Papilloma Virus (HPV) testing by PCR. This has massive implications for cervical screening services and also staff that perform cervical cytology.
In 1975, Professor zur Hausen hypothesized that human papillomavirus was a necessary cause of cervical cancer. For this he won the Nobel prize in 2008.
There is little doubt that the evidence supporting primary screening (more or less) in place of cytology is overwhelming, but this raises a few secondary questions…
What is the optimal screening interval, given that it takes several years for cervical cancer to develop from primary HPV infection.
When is the optimal age to stop screening?
What future impact will the recently introduced HPV vaccine have on the cost effectiveness of screening?
This is where we need to be careful. The majority of research trials into HPV testing for cervical cancer screening are carried out/sponsored by the large corporate companies that produce and sell HPV tests. These companies have a clear conflict of interest in the answers to the three questions above. This is not their fault, but the conflict is there nevertheless. We just need to be very careful with anything we read (or are given to read) on the topic
HPV is a fascinating area. If I was setting an exam on molecular testing, then HPV would be more or less at the top of my list of questions, and I am afraid I would be a ruthless examiner!
HPV vaccines (Gardasil and Cervarix) are now available in a lot of countries and are funded in some of them. You would think that a vaccine designed to prevent (primarily)cervical cancer would be very popular and uptake by the population, particularly amongst females, would be high.
Unfortunately in a lot of places this has not proved to be the case…
Aside from issues of cost and accessibility which may affect some cohorts, here are some other barriers as detailed in a nice NZ article on the topic. I have summarised them as follows:
“My daughter is too young.” However vaccinating at age 12 allows for the majority of people to be vaccinated prior to commencing sexual activity. It is also an age at which immune response to the vaccine is at its highest.
“Why bother with the vaccine if I’m already sexually active.” Still benefit as young people unlikely to have contracted all the strains in the vaccine.
“Vaccines are unsafe/I don’t believe in them.” HPV vaccine has a strong safety profile and any “risk” is dwarfed by risk of not vaccinating
“The vaccine will promote unsafe sex/promiscuity.” No evidence whatsoever that this is the case.
“Why bother, that’s what condoms are for.” Being vaccinated not a reason to stop using condoms, nor is the regular use of condoms a reason not to be vaccinated. Condoms does not reduce HPV transmission by 100% anyway.
However I think there is another important barrier…. In a lot of countries, parental consent is required for the vaccine. However I suspect that there are a lot of parents who might think that the vaccine is unecessary as their daughter would never get engaged in early or high risk sexual activity, otherwise named as the “My little darling would never do that syndrome.”
I am sure the above reason is possibly the main one in explaining why vaccine uptake (in contrast to most other vaccines) in some countries is lower in middle class than in working class areas.
I am not sure how to get around the aforementioned barrier. Some places in USA have tried to make the vaccine compulsory, causing a lot of controversy in the process.
I guess it is just natural parental instinct to think the best of our children, when in actual fact they are probably only as “perfect” as we were at that age….
p.s. Giving boys the HPV vaccine is another (controversial) topic which I will discuss in another article.