Testing for HPV
HPV is a very common virus and 80% (four out of five) of people will become infected with some type of the virus during their lives. For most the infection will be cleared naturally, but if the HPV infection is not cleared and it becomes persistent then there is a risk of developing abnormal cells and cancer. There are many different strains of HPV, some are considered ‘high risk’ and others ‘low risk’ of causing cancer. Around 20 strains are oncogenic (cancer causing) and associated with the development of cervical cancer, the are the so called ‘high-risk’ HPV types [1]. If a woman contracts a high risk strain of HPV and this becomes a persistent infection then she has a higher risk of developing abnormal cells and thus should be monitored more closely. HPV testing can help to distinguish between women who have a higher risk of developing abnormal cells and thus also cervical cancer, from those who have a very low risk. It can also reduce the number of unnecessary screening appointments and colposcopies among women with borderline screening results.
HPV testing is not currently available UK wide. From April 2011 it will be slowly introduced in certain parts of the UK (see your region below for more details).
England
From April 2011, the NHS Cervical Screening Programme (NHSCSP) will gradually introduce HPV testing and it will be performed on the cytology samples from all women whose screening results come back with borderline or mild dyskaryosis. This model is called HPV Triage. Women with either borderline or mild dyskaryosis have only around a 15-20% chance of having a significant abnormality that requires treatment [2]. The HPV test is useful because it is effective at identifying which women may need treatment. If HPV is found they will be referred for colposcopy [3] if HPV is not found they will be returned to routine screening every three or five years depending on their age. HPV causes cervical abnormalities which can with time develop into cancer. If a woman does not have HPV even though her screening result suggested abnormal cells, the risk of cancer being present is negligible, thus, the women can return to normal screening.
The NHSCSP will also be introducing the HPV 'Test of Cure'. This will be offered to women who have undergone treatment for cervical abnormalities (CIN). This means that HPV tests will be carried out on samples from women who have a normal screening test result after having treatment for CIN. If HPV is not found then the women will not be recalled for screening for a further three or five years, depending on her age. If, however, HPV is found or the screening test does show an abnormality the women will be referred again to colposcopy.
Scotland
NHS Scotland is currently piloting HPV ‘Test of Cure’. The Test of Cure Early Implementation Study commenced 1 February 2011 in the following Scottish sites: NHS Grampian, Orkney, Shetland, Highland, Western Isles and Lothian.
Following current Scottish protocol, women treated for CIN 2 and 3 in all other NHS Board areas have a cervical 'smear test' (cytology alone) every year, for five years following their treatment, before they can be considered for return to routine screening.
From the 1st February 2011, women in the pilot sites who have been treated for CIN 2 and 3 since 1st August 2010 will have their sample tested for HPV in addition to cytology at 6 and 12 months and a cytology test will also done at 24 months.
The HPV test is important because it is now known that women who are HPV negative at 6 months and 12 months following treatment, and who also have no cytological changes at 6, 12 and 24 months after treatment can be returned to routine screening. This means women can return to routine screening three years earlier than at present.
References
- Li N, Franceschi S, Howell-Jones R, Snijders PFJ and Clifford GM (2011) Human papillomavirus type distribution in 30,848 invasive cervical cancers worldwide: variation by geographical region, histological type and year of publication. International Journal of Cancer 128, 927–935.
- ~ (2010) Colposcopy and Programme Management, Guidelines for the NHS Cervical Screening Programme (2nd ed), NHSCSP Publication No 20, 12-13.
- NHS Cervical Screening Programme HPV Triage programme: http://www.cancerscreening.nhs.uk/cervical/hpv-triage-test-flowchart-v2.pdf. Accessed 28.03.11.
Last updated: 29/03/2011
