Extrait
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Abstract
Primary screening of cervical cancer has been faced with an array of challenges which
are attributable to the lack of appropriate technology. These challenges compromised the
effectiveness of screening programs in different countries. It is apparent that the detection of
cervical cancer precursors forms the basis for the success of screening programs for cervical
cancer leading to the reduction of cervical cancer incidence and prevalence trends. Currently,
there are two diagnostic methods that can be used for primary screening of cervical cancer: Pap
cytology and HPV DNA test. However, the comparative effectiveness of this diagnostic tests
indicate that HPV test is more effective than Pap cytology which is used as a first-line diagnostic
method in cervical cancer prevention programs in many countries. Cytology testing and HPV
testing differ significantly on the level of accuracy and sensitivity. Evidence studies indicate that
HPV test exhibits high sensitivity and accuracy compared to Pap test. In a publicly-financed
healthcare system such as the US, Canadian and EU, HPV testing has been proven to be more
cost-effective than Pap test. Therefore, there is need to adopt HPV test for triage and primary
screening.
Keywords: Pap cytology, HPV co-testing, human papillomavirus, sensitivity, first-line, negative,
unclear, positive, colposcopy
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Contents
Introduction ... 4
HPV Testing In Primary Cervical Cancer Screening ... 4
HPV Testing in America ... 6
HPV Testing in Canada ... 6
HPV Testing in Australia ... 7
Cytology Testing In Primary Cervical Cancer Screening ... 7
HPV Co-Testing (HPV + Cytology) ... 8
Comparison between Cytology Testing and HPV DNA Testing ... 8
Sensitivity and Accuracy ... 8
Cost-Effectiveness ... 9
Vaccination Effect ... 10
Reason for Change of Primary Screening Strategy ... 10
Factors Influencing Change of Strategy ... 10
Conclusion ... 10
References ... 12
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Introduction
Over the years, primary screening of cervical cancer has been faced with an array of
challenges which are attributable to the lack of appropriate technology. These challenges
compromised the effectiveness of screening programs in different countries. It is apparent that
the detection of cervical cancer precursors forms the basis for the success of screening programs
for cervical cancer leading to the reduction of cervical cancer incidence and prevalence trends.
However, the introduction of new technology in screening for cervical cancer seems to have
improved epidemiological responses through early detection of the disease. For instance, the
application of human papillomavirus (HPV) DNA testing and cell (pap) cytology are currently
considered the mainstay diagnostic pathways in primary screening for cervical cancer (1).
However, these new technologies exhibit diverse degrees of effectiveness in the healthcare
system. Therefore, this literature review focuses on the comparative effectiveness of HPV DNA
testing and cytology testing based primary screening diagnostic methods within a cervical
screening program.
HPV Testing In Primary Cervical Cancer Screening
HPV testing has been accepted as an alternative diagnostic method for primary screening
of cervical cancer in women. This approach focuses on detecting HPV types that are believed to
present a high risk of cervical cancer (2). HPV is a virus that infects the genital areas of humans.
This virus is usually transmitted through sexual intercourse, and its infection does not manifest
signs and symptoms (5). In most cases, the body fights off the infection by clearing the virus
from the body through immune response mechanisms. Center for Disease Control and
Prevention (CDC) reaffirms this phenomenon by stating HPV infection disappears within two
years without causing any health problems, and this phenomenon is attributable to defense
responses of the immune system (3). However, it has been found out that HVP causes cervical
cancer after remaining in the cervical cells for a prolonged period. This occurs in two different
ways depending on the type of HPV involved. Research indicates that some HPV types cause
cervical cancer by causing changes on a woman's cervix. On the other hand, HPV can cause
morphological changes in cervical cells; thus, leading to the development of genital warts (5).
However, it is worth noting that the HPV types that have been found to be responsible for
causing genital warts in both women and men are different from those that cause cervical cancer
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in women. Evidence studies indicate that genital HPVs comprises of more than 40 related HPV
types which are responsible for most STIs. However, it is worth noting that only 14 HPV types
are considered as significant etiological agents for cervical cancer. These are considered as
`high-risk' HPV types. Laine reports that often, a high-risk HPV infection is eliminated by the
immune system and it does not manifest health problems. However, it is reported that 10% of
women who are infected with high-risk HPV experience a persistent infection which increase the
risk of cancer. Research indicates that HPV infections, primarily with `high-risk' HPV types
account for all cervical cancers. However, only two `high-risk' HPV types cause about 70% of
cervical cancers in women. Recent studies have identified HPV 16 and HPV 18 as the most
virulent of all the genital HPVs (4).
Therefore, HPV DNA testing (HPV test) is meant for testing the presence of HPV types
related to cervical cancer, but not all types. For instance, the cobas HPV test identifies the
genome from the `high-risk' HPV types. However, it exhibits specificity in the detection of HPV
16 and HPV 18, the most virulent `high-risk' HPV types. Ordinarily, cervical cancer is common
among women aged 30 years and beyond, although some cervical cancer cases have been
reported in women at the ages of 20 and 29 years. Evidence studies indicate that HPV is not
common in young women because they have an increased innate ability to fight off HPV
infection within a few years compared to women older than 30 years (3). This is the reason HPV
testing is recommended for screening of cervical cancer in women who are older than 30 years of
age. It focuses on detecting HPV types which cause the growth of abnormal cervical cells or
cervical cancer.
In practice, a negative HPV test implies the absence of any of the `high-risk' HPV types
in a woman; thus, the risk of cervical cancer is relatively low. On the other hand, a positive HPV
test implies `high-risk' HPV types are present. This implies that a woman is suffering or likely to
suffer from cervical cancer (3). In the case of cobas HPV test, women with HPV 16 and HPV 18
are required to undergo colposcopy, in order to enable for the examination of cervical cells. As a
result, it is possible to determine whether a woman who tests positive for the two HPV types has
abnormal cervical cells, a characteristic of cervical cancer, or it has not yet set. On the other
hand, a positive test for the other 12 high-risk HPV types does not warrant for colposcopy. In
this case, a Pap test is performed to determine the necessity of colposcopy (4). However, the
application of HPV test depends on the guidelines stipulated by different countries.
Fin de l'extrait de 13 pages
- Citation du texte
- Patrick Kimuyu (Auteur), 2018, The Comparative Effectiveness of Cytology Testing and HPV DNA Testing Based Primary Screening Pathways within a Cervical Screening Program, Munich, GRIN Verlag, https://www.grin.com/document/388418
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