PART ONE
General Cytology
The system of internal monitoring of laboratory quality includes
a set of actions, which should be developed and disseminated
in a coordinated way, involving the various stages in the work
process, from collecting a sample to issuing the report. The
system aims to accompany and evaluate the cyto- and histo-
pathologic diagnostic procedures in the laboratories, thus
helping to determine areas where improvements can be planned
and implemented, and also evaluate the impact of these actions
and the incorporation of new practices.
In some situations, the indicators measured in the lab can
show evidence of problems in previous stages, as for example in
the collection of material or in the use of an inadequate fixer. At
these times, it is the role of the lab, acting as an integral part of
the network, to inform the health units that send the material
for examination to improve quality in a team effort, assisting in
the planning and implementation of corrective measures and
improvements.
It is recommended that laboratories have a system that per-
mits monitoring of test quality, establishing evaluation criteria
and maintaining records of the results found. This is a simple
and low-cost measure that reflects technical advances of the staff
involved, improving the relationship between the clinic and the
lab, and in the last analysis improving care to the patients.
Early Detection of Cancer in Other Sites
As mentioned at the beginning of this chapter, screening refers
to the use of simple tests across a healthy population in order
to identify individuals who have disease, but do not yet have
symptoms. Early diagnosis, a concept different from screening,
refers to the detection of early clinical stages of disease in
symptomatic subjects.54
Evaluations of the potential of the Pap test to be a practical
screening test for endometrial cancer have shown both sensitiv-
ity and positive predictive value too low. It is likely that the early
detection of some endometrial cancers are mainly incidental.
However, abnormal endometrial cells on the Pap test may be
markers for increased risk, especially when they are present in
the secretory phase of the menstrual period, or when the patient
is postmenopausal.55 When unexpected bleeding occurs, evalu-
ation becomes diagnostic rather than screening and the woman
should undergo an endometrial biopsy and/or other diagnostic
tests as appropriate.56
Prospective studies of lung cancer screening have not demon-
strated persuasively that screening for lung cancer with sputum
cytology in combination with chest radiography saves lives.56,57
Although none of the studies showed fewer deaths in the experi-
mental group than in the control group, none of the studies
compared disease outcome in a group offered screening with a
group strictly not invited to, or encouraged to, have screening.
Sputum cytology was believed to have potential for the early
detection of lung cancer, but showed little added advantage over
chest X-ray in the NCI cooperative trials, and was not associated
with any reduction in deaths from lung cancer.56 However, spu-
tum cytology was effective in identifying roentgenographically
occult lung carcinoma in its early and occult stages, particularly
in patients at high risk for this disease, where lung carcinoma
was suspected on the basis of symptoms, smoking, or airflow
obstruction.58
Esophageal cancer has a very poor prognosis, mainly because
most tumors are asymptomatic and do not receive medical
attention until they are unresectable. Early detection is the key
to the treatment. At the current time, screening and surveillance
for esophageal cancer is still controversial and screening is not
recommended except for very selected subgroups. The presence
of risk factors such as long-term tobacco or alcohol use, achala-
sia, or squamous head and neck cancers may identify selected
groups for screening.59
Another indication is in high-incidence populations, such
as those found in northern China where esophageal cancer is
endemic.60 Since the late 1950s, Chinese scientists have per-
formed many studies to develop early detection strategies for
this disease. The principal early detection technique developed
was esophageal balloon cytology. With this technique it was
possible to collect exfoliated cells and scrape the surface of the
esophageal mucosa. Although the comparison of cytological
diagnoses with concurrent histological findings showed low
(14-36% ) sensitivities for the cytological detection of biopsy-
proven cancers, cytologic screening could decrease the mortality
by facilitating early detection of the disease.61 Positive cytology
must be verified by endoscopy and biopsy.
Urine cytology is an inappropriate test for screening the
general population. Because of the low prevalence of bladder
cancer, the positive predictive value of the tests is low. There
is inadequate evidence to determine whether screening for
bladder and other urothelial cancers would have any impact
on mortality.62
Urinary cytology can be helpful in the follow-up of patients
exposed to carcinogenic agents by contributing to early diagnosis
of urinary tract tumors. By far the greatest known environmen-
tal risk factor in the general population is tobacco, especially
cigarette smoking, with individuals who smoke having a four-
to sevenfold increased risk of developing bladder cancer com-
pared to individuals who have never smoked.62,63 Bladder cancer
was first linked to an occupational exposure. An increased risk
of bladder cancer has been identified for a variety of occupa-
tions including chemical and rubber workers, leather workers,
painters, dye workers, truck drivers, and garage and gas station
workers.64,65,66
Urine cytology is primarily used for detection of cancer in
patients like those exposed to industrial chemicals and metals,
cigarette smokers, and those with schistosomiasis, associated
with increased risks of bladder cancer. Furthermore, it is also
used for diagnosis of symptomatic patients and follow-up of
patients with a history of urinary tract neoplasia.
The use of cytology as a screening test for cancer has
demonstrated discouraging results in sites other than uterine
cervix. In asymptomatic persons it can be more harmful than
beneficial for the possibility of false-positive results, leading to
unnecessary expense and morbidity from follow-up procedures.
However, in a general way, it has had an important role in the
diagnosis of early clinical stages of disease when already symp-
toms are proven or when there has been clinical suspicion. Early
detection of cancer greatly increases the chances for success-
ful treatment, education being one of the most important ele-
ments for recognizing possible warning signs and taking prompt
action that will lead to early diagnosis. Increased awareness of
possible warning signs of cancer can have a great impact on the
disease.
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