The new Cervical Screening Test (CST) will replace the Pap smear in 2017
(Get with the program!)
FREQUENTLY ASKED QUESTIONS
- What’s going to change?
- Why are we changing?
- Why HPV DNA testing?
- But is a testing interval of FIVE years safe?
- Is HPV DNA testing reliable?
- Will HPV DNA testing miss some cases of cervical abnormalities or cancer?
- What about HPV DNA negative cervical cancer?
- But I had the Gardasil or Cervarix HPV vaccine – shouldn’t I be protected now?
- What is ‘reflex cytology’?
- But I don’t like change and want to continue doing Pap smears…
- Why are we not screening under 25 year olds?
- I’m still not convinced – can I do the Cervical Screening Test more often than every five years?
- What about ‘self-collection’?
- What happens when I’m 70-75 years old?
What’s going to change?
The major change is that pap smears will no longer be performed – instead, the test will be for HPV DNA and will be called the ‘Cervical Screening Test’. Unfortunately, it is still done via the same vaginal speculum examination and cervical swab so the patient experience will be the same.
SUMMARY OF CHANGES
|Old Cervical Screening Program||NEW Cervical Screening Test|
|Order a ‘Pap smear’||Order a ‘Cervical Screening Test’|
|Speculum + Endocervical swab||Speculum + Endocervical swab|
|Swab spread on a glass slide+/- ThinPrep/Surepath||Swab placed in ThinPrep/Surepath liquid medium|
|Pap every two years||HPV test every FIVE years|
|Age 18-70||Age 25-75|
|Normal pap – repeat in 2 yearsAbnormal pap:
LSIL – repeat in a year
HSIL – refer for Colposcopy
|HPV negative – repeat in 5 yearsHPV positive:
High risk HPV – Colposcopy
Other HPV – reflex cytology:
If cytology NEGATIVE or LSIL – repeat HPV 12 months
If cytology HSIL – Colposcopy
|Symptomatic: refer for Colposcopy||Symptomatic: refer to Colposcopy|
|No previous screening or poor attendance: no follow-up||Never screened or overdue for screen by >2 years + Age>30: offer self-collection|
Why are we changing?
The Pap smear screening program has been very effective in reducing cervical cancer incidence and mortality since it was introduced in 1991 – over the last two decades, cervical cancer incidence has halved.
However, the rate of cervical cancer incidence and mortality has been about the same for the last ten years – a change is needed to reduce it further.
It makes sense to test for HPV infection as the first step towards development of cervical cancer – rather than when the infection has already caused abnormal cervical cells like we do with the Pap smear now.
But is a testing interval of FIVE years safe?
We know that many women are infected with HPV in their lifetimes but it seems that most women ‘clear’ the infection. It is only in some women that the infection persists and it is that persistent HPV infection that starts causing abnormal cells on the cervix that have the potential to develop into cancer.
Studies have shown that it takes years – on average 10-15 years – of persistent HPV infection to develop cancer.
If a test for HPV DNA is negative, then even if a woman becomes infected before the next screen in five years (and the HPV infection persists), it will not have developed into cancer before it is picked up in the next test.
The caution would be in people with immune problems such as those taking immunosuppression for an organ transplant or an immunodeficiency syndrome – in these people, progression of cervical abnormalities to cancer may be faster than the average.
Is HPV DNA testing reliable?
Multiple studies on HPV DNA testing have shown it to be a reliable test. Compared to the Pap smear, HPV DNA testing has a better negative predictive value and increased detection of high-grade cervical abnormalities.
Will HPV DNA testing miss some cases of cervical abnormalities or cancer?
No test is perfect but the fact is that HPV DNA testing is better than Pap smear screening. Pap smears have worked so well that it is easy to overlook that Pap smears also miss cervical abnormalities and even cancer.
But again, Pap smears were also not perfect. We can only be vigilant in women with unusual symptoms and refer for Colposcopy and biopsy as needed.
But I had the Gardasil or Cervarix HPV vaccine – shouldn’t I be protected now?
HPV has hundreds of types of which about nine have been identified as ‘high risk’ – infection with these types is associated with cervical abnormalities that may progress to cancer. Infection with ‘low risk’ types may cause low grade cervical changes but these tend not to progress to cancer.
The HPV vaccines only protect against infection by a few ‘high risk’ strains so you are still at risk of infection with the other ‘high risk’ strains. There is a new nine strain HPV vaccine (nonavalent HPV vaccine) that looks set to be released in Australia soon.
Also, the HPV vaccine is only preventative – so if you had already been infected with those HPV types, than the vaccine does not ‘cure’ you of them.
If there are no abnormal cells, then it seems that the HPV infection has not caused cervical abnormalities (yet). But we do want to keep a closer eye on the situation, which is why the Cervical Screening Test is repeated in one year rather than five years.
If there are abnormal cells, but they look low-grade, then they have a high chance (up to 70%) of spontaneously resolving over a year. So again, the Cervical Screening Test is repeated in a year.
If there are abnormal cells and they look high-grade, then a Colposcopy by a Gynaecologist is needed.
The exception is if the HPV types detected are types 16 or 18 – these two strains are more likely than other HPV types to cause high-grade abnormalities and cancer. The recommendation is for a Colposcopy regardless of the cytology result.
The success of Pap smears have, among other things, relied upon expert cytopathologists – these are the people who look at the Pap smear slides and tell us if the cells are abnormal or not.
With the new Cervical Screening Test, HPV DNA testing is automated (done by a machine). There will only be a small percentage of samples that will need ‘reflex cytology’ and even that will mostly be done by machines and probably quality assured by a cytopathologist.
This means that there will be a dramatically reduced need for cytopathologists and, recognising this, existing cytopathologists have already resigned or been retrained.
After the introduction of the new Cervical Screening Test, there will be insufficient expert cytopathologists to ensure a Pap smear screen will be as good as it is currently.
This is based on data that:
- Current Pap smear screening has made no impact on cervical cancer under 25 years of age
- There are no deaths from cervical cancer under 25 years of age in Australia
- Less than 0.2% of cervical cancers occur under 25 years of age
- Other countries do not recommend screening under 25 years of age – yet their cervical cancer incidence and mortality is the same as Australia
There will be some women under 25 years of age who will have cervical abnormalities and, on the rare occasion, cancer. These cases will usually have some kind of symptoms and we will still be vigilant in testing and this is covered under the new Cervical Screening Test.
I’m still not convinced – can I do the Cervical Screening Test more often than every five years?
Yes, you can screen for HPV DNA as often as you wish but the recommendation is every five years. There is unlikely to be much benefit in screening more often than every five years. Also, an HPV DNA test will only qualify for a Medicare rebate if the last test was at least 4.5 years ago – otherwise, you will have to pay the full cost.
What about ‘self-collection’?
For those who, for whatever reason, cannot have a speculum examination, there is an option for a self-collected specimen. The criteria for a Medicare rebate is that a woman must be over 30 years old and have never had any screening before or are overdue for a screen by more than two years.
The conditions are still being finalised but currently, a vaginal swab is collected by the woman themselves, while at a medical practice and the sample is sent for HPV DNA testing. However, if HPV DNA is positive, then a speculum vaginal examination will be recommended to collect a sample for cytology and likely a Colposcopy will be required.
This option is not recommended for everyone as self-collected vaginal specimens are not as sensitive as an endocervical swab. Also, there is benefit in having a clinician actually look at the cervix (and also the perineum and vagina).
Of note, cervical cancer still occurs in women over 75 years old but with the slow development of cervical abnormalities into cancer over years and even decades, it is unlikely to be the primary concern at this age. People are living longer and longer so recommendations may change in the future.
Have more questions?