Most low-grade abnormalities on Pap smears spontaneously regressed within 36 months in a cohort study of adolescents and young women, and study investigators say the finding lends support to the practice of monitoring these lesions with regular cytology.
Colposcopy is “unwarranted and leads to unnecessary intervention, morbidity, and cost,” said Anna-Barbara Moscicki, M.D., and her associates at the University of California, San Francisco.
Of 187 patients aged 13-22 years who developed low-grade squamous intraepithelial lesions (LSIL), 61% were free of LSIL after 1 year, and 91% were free of LSIL at 3 years' follow-up.
Progression to high-grade disease occurred in 3% of the patients (Lancet 2004;364:1678-83).
The patients were part of a larger 10-year longitudinal study of human papilloma virus (HPV) infection.
The women were examined every 4 months by cytology, colposcopy, and HPV DNA status. Both prevalent and incident LSIL cases were included in the study, and regression was defined as having at least three consecutive normal Pap smears.
The investigators found no associations between LSIL regression and HPV status at baseline (time of the first LSIL), age, sexual behavior, contraceptive use, substance or cigarette use, or incident sexually transmitted infection.
Nor did they find any significant differences in rates or timing of regression between patients who underwent biopsy and those who didn't, nor between patients whose LSIL status was confirmed by histology and those with LSIL confirmed by a normal biopsy.
The investigators did find that patients' current HPV status—rather than their baseline status—was important. A negative HPV test at a subsequent visit “shows a good likelihood that LSIL has regressed,” which suggests that HPV testing “could be helpful in monitoring LSIL,” they said.
In addition, the findings suggest that the persistence of multiple HPV types slows rates of regression, but this needs to be examined more closely. More study is also needed to better define appropriate screening strategies, Dr. Moscicki and her associates said.
The findings are similar to those of a smaller study from Brazil, published in 2003 in the Journal of the National Cancer Institute, in which an estimated 92%-95% of cases regressed within 24 months, and 5%-6% progressed, according to Anne Szarewski and Peter Sasieni of Cancer Research UK.
“It is becoming increasingly clear that LSIL is a transient manifestation of HPV infection that will only rarely progress to HSIL,” they wrote in an accompanying editorial (Lancet [in press]). “Since there is no point in treating LSIL in young women … we see absolutely no role for colposcopy in adolescents as part of routine management,” they concluded.