Natural Progression of an Abnormal Pap
Frederick R. Jelovsek MD
Approximately 2-5% of Pap smears will have an abnormal result.
The usual abnormal result categories are:
-
ASCUS - Atypical cells of uncertain significance
-
low grade squamous intraepithelial neoplasia
(LGSIL) or mild dysplasia
-
high grade squamous intraepithelial neoplasia (HGSIL) consistent
with moderate or severe dysplasia
Many women want to know how serious these findings are. The way
we know what the natural progression of these abnormal Paps is
to follow the woman without treating or doing anything to alter
the normal progression (worsening) or regression (improvement) of
these Paps.
A recent study, Melnikow J: Natural history of cervical
squamous intraepithelial lesions: A meta-analysis. Obstet Gynecol
1998;92:727-35, looked at all scientific studies in the
literature since 1970 in which women with abnormal Paps were
followed but not treated. They then analyzed how often the
specific Pap smear improved on it's own and how often it
progressed to a worse lesion:
Abnormal Pap Smear
Natural Progression and Regression
| Abnormal Class |
Regression to Normal |
Progression to higher grade over 24 Months |
Progression to invasive cancer over 24 Months |
| ASCUS |
68% |
7% |
0.25% |
| LGSIL |
47% |
21% |
0.15% |
| HGSIL |
35% |
23% |
1.44% |
The studies analyzed took the Pap smear on entry as the true
finding when in fact we know the Pap is a screening test and as
such has some false negatives (could explain progression) and
false positives (could explain regression).
How does HPV (human papilloma virus) affect progression of the
Pap? In one study(1), The rate of CIN
progression was higher with HPV (50.5%) than without HPV (35.4%).
Of the CIN cases with HPV 16, 56.5% progressed, while 30.8% of
the CIN cases with HPV 6 and/or 11 and 35.4% of the CIN cases
without HPV progressed. In other words, HPV subtype 16 was
associated with a higher progression rate but not all subtypes of
HPV.
Another older study before HPV sub typing(2),
looked at progression or regression of a Pap smear showing HPV.
| Abnormal Class |
Regression to Normal |
Progression to higher grade over 24 Months |
Progression to invasive cancer over 24 Months |
| HPV only |
45% |
16% |
0% |
| HPV and LGSIL |
50% |
0% |
1. Konno R, Paez C, Sato S, Yajima A, Fukao A
HPV, histologic grade and age. Risk factors for the progression of cervical intraepithelial neoplasia.
J Reprod Med 1998 Jul;43(7):561-6
2. Rome RM, Chanen W, Pagano R
The natural history of human papillomavirus (HPV) atypia of the cervix.
Aust N Z J Obstet Gynaecol 1987 Nov;27(4):287-90
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