Cervical smears which are mildly to moderately dysplastic are more likely to revert to normal than to progress to cancer, according to a new study (Journal of the National Cancer Institute 1999;91:252-8).
Women with findings classed as mildly dysplastic are often referred for immediate colposcopy and biopsy. This latest research may lead to less rigorous follow up tests for women whose cervical smears are only mildly dysplastic.
University of Toronto researchers led by Phillipa Holowaty reviewed the records of 17946 women who were diagnosed with mild, moderate, or severe cervical dysplasia between 1970 and 1980. Progression to cervical cancer was determined by correlating the smears to cases of cervical cancer listed in the Ontario Cancer Registry. Follow up was continued through 1989.
The authors found that cases of mild or moderate dysplasia were more likely to regress than to progress. For women diagnosed with mild dysplasia the risk of progression to severe dysplasia or worse was only 1%per year.
The majority of untreated cases of mild dysplasia returned to normal within two years, although 29%were still present at two years or had progressed. Most cases of moderate dysplasia also spontaneously reverted to normal, but the risk of progression from moderate dysplasia was 16%within two years and 25%within five years.
The relative risk of progression to cancer was 2.5 for moderate dysplasia and 4.2 for severe dysplasia compared with mild dysplasia. Moreover, most of the excess risk of cervical cancer associated with severe or moderate dysplasia occurred within two years of the initial dysplastic smear.
The researchers concluded that their data support a less invasive initial surveillance strategy for mild dysplasia, and that women with mildly dysplastic findings should have a repeat smear six months later rather than undergoing an immediate colposcopic examination with biopsy.
They also suggest that the ”moderate“ category may have prognostic significance and provide a clinically useful distinction.
Currently, both moderate and severe dysplasia, also known as cervical intraepithelial neoplasia grades II and III, are classed as high grade squamous intraepithelial lesions and treated similarly, with colposcopy and biopsy.
In an editorial accompanying the article, Cathy Critchlow and Nancy Kiviat, of the University of Washington School of Medicine, noted that it was unclear whether the ”moderate“ category was a true entity or represented severe and mild cases that were difficult to classify.