Frederick R. Jelovsek MD
The human papillomavirus (HPV) has been identified as the most common
culprit associated with abnormal Pap smears. Some strains of HPV
are apparently more virulent than others and HPV subtypes 16, 18,
31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and 68 have been
associated with severe grades of cervical dysplasia and invasive
cancer of the cervix. DNA test is used to identify subtypes of
HPV and up to now it has been more expensive and inconvenient to
offer as routine testing. Theoretically, if all women with
abnormal Pap smears could have HPV subtype testing then those
associated with the more virulent strains would be the only ones
requiring treatment.
Right now the rule-of-thumb in the U.S. is to follow women with
ASCUS (atypical squamous changes of undetermined significance)
and mild dysplasia (CIN I) with repeat Pap smears every 3-6
months. That is because most of them go away on their own as the
woman's body mounts an immune response. Moderate or severe
dysplasia changes are usually treated with procedures that
destroy the affected cells along with normal tissue. It would be
nice to know which women with ASCUS or mild dysplasia were going
to get worse with time. Then they could be treated early. Also it
would be nice to know which women with moderate or severe
dysplasia could be followed with just repeat Pap smears rather
than having to have a destructive procedure to the cervix that
may affect future fertility.
With the advent of the thin Pap, there is fluid left over
from the specimen that can be tested for HPV DNA without having
the woman return for an additional visit and procedure to obtain
a specimen -- Pap or biopsy. Thus if a Pap is abnormal, it can be
immediately tested for worrisome HPV strains. A recent study
looked at the practicality of this. Wright Jr. TC, et al.:
Reflex human papillomavirus deoxyribonucleic testing in women
with abnormal Papanicolaou smears. Am J Obstet Gynecol 1998;
178:962-6.
These authors studied 265 women with different grades of Pap
smears and biopsies. They found that in patients who had ASCUS,
the lowest grade of Pap abnormality, HPV DNA testing could
identify 90% of those women who were likely to have a more severe
lesion (high grade dysplasia) on actual biopsy. Unfortunately,
with the higher grades of Pap abnormality, the testing was not
sensitive or specific enough to be useful as to which women could
be followed rather than biopsied.
While more studies have to be done in this area, our knowledge
about abnormal Paps and HPV has advanced significantly in the last
decade and if the thin Pap test becomes more widely used, we will
see more studies about HPV association that will help us know
in which instances to treat or not treat with greater precision.
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