3
Cytologic Screening Programs
New Developments in Cytological
Screening
Liquid-Based Cytology (LBC)
New technology for alternative and complementary forms of
screening alterations in the cervix has recently been proposed,
and one of these is known as liquid-based cytology (LBC). In
this method, the cervical cells are immersed in a conserving
liquid before being fixed on the slide, avoiding desiccation and
reducing the quantity of obscuring material. Liquid cytology can
be prepared by manual or automated methods. LBC methods
have been used routinely in laboratories in the majority of devel-
oped countries, whereas developing nations more frequently
use manual liquid cytology methods.67-69 Although the cost is
higher, various studies have shown the advantages of using LBC.
Special attention has been given to the use of residual material
in the vial, which can be used for:
(a) Preparation of additional slides;
(b) Molecular testing of infectious agents;
(c) DNA cytometry; and
(d) DNA ploidy analysis.
An additional sample can be potentially useful in clarify-
ing diagnoses in cases showing undetermined nuclear atypia,
questionable graduation of the lesion, excess or scarcity of cells,
blood, or exudates.70,71
Since their introduction and approval as a method of detec-
tion of lesions on the cervix, the various LBC methods have been
the object of diverse studies that emphasize the lower number
of interpretative errors,70 more effective diagnosis of lesions, and
greater speed of analysis due to the ease of reading the slides.72
Emphasized also is the reduction of unsatisfactory cases due to
collection of samples and the increase in the number of cases
diagnosed with low- or high-degree lesions. Because of these
findings the FDA approved LBC in 1996 as a screening method,
and today in the USA around 80% of cervical cytology tests use
the liquid base.24
However, despite the benefits shown by liquid cytology, stud-
ies point out the need to evaluate the cost-benefit of using one
or other type of cytology, as the cost of LBC is still high when
compared with the conventional method. A recently published
review showed that the principal automated techniques, used
in the USA, have a questionable cost-effectiveness ratio.70 Scot-
land adopted the method and the UK's National Health Service
(NHS) is recommending the introduction of the method in the
screening program.
Automated Cytology
Automation of cytology has been studied for many years with
the purpose of introducing methods that reduce errors caused
by human fatigue, and that can detect lesions when the sample
contains a lesser number of abnormal cells. Automated methods
available can be used with conventional cytology or with LBC.
Despite technological development and the emergence of auto-
matic apparatus, studies have shown that automated screening
would not improve the outcome of cervical cytology. For addi-
tional information on automated systems see Chapter 34.
One of the advantages of this methodology is the possibility
of testing a large number of cases with a minimum possibility
of error.73 Its association with LBC would also provide a still
reduced number of unsatisfactory cases. Nevertheless the high
cost of equipment and the implementation of the technology
makes its use difficult principally in developing nations.
Concluding Remarks
Cytologic screening is an important method for certain diseases,
especially cervical cancer, and an example of successful preven-
tion of this disease. The majority of cervical cancer occurs in
developing countries. The success of cervical cancer screening
is shown by its ability to reduce the incidence of cervical can-
cer and the resulting mortality. The integration of procedures is
essential for a successful screening program. Recently new tech-
nologies for alternative and complementary forms of screen-
ing such as liquid-based cytology and automated cytology have
been proposed. A combination of methods has been proposed
in an attempt to improve the sensibility of the Pap test. Among
these, the association of cytology with the molecular test for
HPV using hybrid capture has been highlighted. Automated
cytology may be used for the purpose of reducing human
errors caused by human fatigue, and to detect lesions with a
lesser number of abnormal cells in the sample. HPV vaccine
will be an additional tool in the strategies to reduce morbidity
and mortality from cervical cancer and will be a component
of a comprehensive strategy with the long-term goal of elimi-
nating the disease. Cytologic screening can also be performed
in selected high-risk populations for lung, esophageal, and
bladder cancer.
References
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Anderson GH, Flynn KJ, Hickey LA,
et al. A comprehensive internal quality
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Papanicolaou GN, Traut HF. The
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Lazcano-Ponce E, Alonso P, Ruiz-Moreno
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World Health Organization. Cytological
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