NEW YORK (Reuters Health) – Cervical intraepithelial neoplasia grade 1 (CIN 1) found on biopsy provides no information on the risk of progression to CIN 3 beyond that of a human papillomavirus (HPV) infection, researchers report in the December issue of Obstetrics and Gynecology.

As a consequence, “it might (be) difficult to justify differential management by histologic status in this population,” note Dr. Philip E. Castle of the American Society for Clinical Pathology in Washington, D.C., and colleagues.

The researchers reviewed data from a study of women with atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesions. In all, 594 had a diagnosis of CIN 1 at enrollment and the remaining 570 had negative cytology or had no biopsy taken at colposcopy.

In the women with CIN 1, the two-year risk of CIN 3 was 10.3% compared to 7.3% in those with negative findings and 6.4% in those without biopsy at colposcopy. These, the researchers point out, are “statistically significant but small absolute risk differences. Given the general similarities in risk, these outcomes of screening might be managed similarly.”

Women positive for HPV16 had a two-year CIN 3 risk of 19.1%. For HPV18 and other carcinogenic HPV genotypes, the figures were 13.9% and 5.7%, respectively.

After taking HPV genotypes into account, the authors point out that having CIN 1 was no longer associated with an increase in CIN 3.

“A CIN 1 diagnosis,” Dr. Castle told Reuters Health by email, “does not represent a significant risk factor for CIN 3 (cervical precancer) above the risk attributed to its molecular cause, genotype-specific HPV infection.”

But women who were diagnosed with CIN 1 were more likely to have HPV16, which in turn increased the risk of CIN 3.

“Doctors should be cognizant that HPV16-positive (and HPV18-positive) women are at an elevated risk of CIN 3 in the subsequent few years,” the researchers conclude.

SOURCE:

The Clinical Meaning of a Cervical Intraepithelial Neoplasia Grade 1 Biopsy

Obstet Gynecol 2011;118:1222-1229.