HPV testing

Question 1

HPV

Answer 1

• Is one of the most common STIs in the world.
• 15-20% of young sexually active women acquire genital HPV infection per year.
• Adolescents who are sexually active have the highest rates of prevalent and incident HPV infection rates
• 50-80% having infections within 2-3 yrs of initiating intercourse.
• 90% of infections clear within 2 years with only a small proportion progressing to cervical pre-cancer and cancer.
• HPV types 16, 18, 31, 33 and 39 have a higher risk of progressing to cancer.
• A cervical smear showing dysplasia, intraepithelial neoplasia or cervical cancer is almost always a result of persistent HPV infection
• In the absence of persistent infection with high-risk HPV types, cervical cancer is not expected to develop.
• There is good evidence that appropriately applied testing for high risk HPV types can play a useful and cost-effective role in the management of women with abnormal cervical smears.

Question 2

HPV vaccination

Answer 2

• Gardasil was introduced to NZ’s vaccination programme in 2008
• Offers protection against HPV types 16 and 18 (as well as 6 and 11 genital wart types).
• It is anticipated that the HPV vaccination programme will bring about a reduction in cervical cancer rates in the future
• In the meantime cervical screening is the most effective way to reduce morbidity and mortality from cervical cancer.

Question 3

HPV testing

Answer 3

• Integrated into the cervical screening programme 1/9/09
• Currently tests for 13 high risk HPV types
• It has a very high negative predictive value (approx 99%)
• It is not indicated in women < 30 yrs of age due to the high prevalence of HPV infection in young women, the vast majority of which clear within 2 yrs and are of little clinical significance
• It can be performed at the laboratory from the same specimen as the smear (LBC), or can be performed on a separate swab

Question 4

Using cervical cytology and HPV together

Answer 4

• The Cervical screening guideline identifies particular areas of management of asymptomatic women with abnormal cervical smears who may benefit from HPV testing.
• This includes:

1. The triage of women 30 years and over with atypical squamous cells of undetermined significance (ASCUS) or low grade changes (without an abnormal smear in the last five years)
2. The follow-up of women who have been treated for a high-grade lesion
3. Post colposcopy management of women with discordant results

Question 5

HPV is used to determine the likelihood of a low grade lesion progressing to high grade lesion for women over 30 yrs

Answer 5

• There is clear agreement that women with high grade abnormalities should be referred to colposcopy but what is less clear is how to care for women with less severe abnormalities.
• The complexity of managing low-grade abnormalities relates to their mostly self-limiting nature, as well as the evidence that they harbour high grade lesions in up to 20% of cases.
• A small number of cases of cervical cancer are diagnosed quite soon after low-grade cytology.
• HPV testing in women over 30 years old will help in the management of these situations.
• A positive HPV test indicates increased risk of developing a high grade lesion, and so can be a useful adjunct to the management of abnormal cell changes seen in smears.

Question 6

Follow-up of women who have been treated for a high grade lesion

Answer 6

• Women who have been previously treated for CIN2/3 are at increased risk of further high grade disease and cervical cancer
• HPV testing changes the management of these women and may negate the need for annual smears for life for many
• Following two consecutive negative smears and HPV tests, 12 months apart, the woman will be able to return to normal three yearly screening intervals.

Question 7

When cytology and colposcopy results are inconsistent, HPV testing can help to clarify appropriate management

Answer 7

• A single colposcopic examination can miss significant lesions
• Discordant results are when a smear result differs from the physical appearances seen at colposcopy e.g. high grade cytology with negative or satisfactory colposcopy
• In these situations HPV testing will assist in management. Following two consecutive negative smears and HPV tests, 12 months apart, the woman will be able to return to normal three yearly screening intervals.