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spring 2007 |
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h
e a l t h t e c h n o l o g y
What’s
the flap about the ‘new’ Pap?
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Jonathan Carpenter Photo |
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Dr. Dan Fontaine |
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In the 1930’s, Dr. George
Papanicalou developed the most successful screening test for cancer —
the Pap test. Despite its success, the Pap test has received much
criticism over its low sensitivity.
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By Dr. Dan Fontaine |
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In the 1930’s, Dr. George Papanicalou
developed the most successful screening test for cancer — the
Pap test. Despite its success, the Pap test has received much
criticism over its low sensitivity.
Since the late 1990’s, there has been a
significant improvement to the technical quality of the Pap smear.
Liquid Based Cytology (LBC) has the advantage of the collection device
being placed in a liquid media. Newfoundland and Labrador is the second
province to ‘go liquid’, while the technology is standard practice in
other countries (Britain and the United States).
This new platform allows for 100 per cent
cell transfer to the laboratory. With conventional Pap smears, the
collection device is discarded following application of cells on the
slide (with loss of up to 80 per cent of sample). LBC also facilitates
removal of potentially obscuring elements often encountered on smears
(for example blood and inflammation or thick areas). LBC delivers a thin
layer of cells making for better visualization of the cells. This
provides a better sample for interpretation.
Another benefit of LBC is that
technologists (who must look at 50 slides in 7.5 hours) have a smaller
and cleaner sample to interpret. A conventional slide can have up to
500,000 cells, whereas a liquid preparation has between 130,000 to
170,000 cells. The Health Care Foundation is fund-raising for an
automated Pap Screener. This equipment will be necessary to avert a
certain crisis as almost half of the technologists in cytology will be
retiring in the next five years.
Another benefit of LBC is the ability to
perform ‘reflex’ testing for Human Papilloma Virus (HPV) – the necessary
cause of cervical cancer. With LBC there will be no need to recall
patients for HPV testing as the residual cytology sample can be tested
for HPV. Only patients over 30 years of age with an Atypical Squamous
Cell diagnosis on cytology will be tested. If the HPV test is positive,
the patient should be referred for colposcopy; if negative, she should
return for annual screening.
The benefits of the new technology,
however, are of no benefit to women who do not present for testing.
Studies have shown a simple physician prompt is the largest influence on
uptake of screening. Give it a try and make cervical cancer history in
Newfoundland and Labrador.
Dr. Dan Fontaine is the director of the
Cytopathology Laboratory with Eastern Health.
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