NEW YORK (Reuters Health) – Over time, cervical intraepithelial neoplasia (CIN) grade 2 eventually resolves spontaneously in about two-thirds of adolescent and young adult women, according to findings reported in the December issue of Obstetrics & Gynecology.

“The main finding is that watchful observation is best in young women with CIN 2. At least up to two years,” Dr. Anna-Barbara Moscicki told Reuters Health via email.

Dr. Moscicki of the University of California, San Francisco, and colleagues note in their report that CIN 1 is considered benign and resolves in 90% of cases, while CIN 3 is classified as a true cancer precursor. “The biologic behavior of CIN 2 is more controversial,” they explain.

To look into the natural history of CIN 2, the team followed 95 patients, mean age 20 years, who were found to have CIN 2 on histology. They were evaluated every 4 months for regression (three consecutive negative cytology and histology results), nonregression, or progression to CIN 3.

Rates of resolution were 38% at 1 year, 63% at 2 years, and 68% by the end of the third year, the investigators report. On the other hand, 15% of cases progressed within 3 years.

Factors that were significantly associated with regression included older age at first intercourse, use of medroxyprogesterone acetate and recent infection with N. gonorrhoeae, the researchers found.

“Gonorrhea was an odd finding,” Dr. Moscicki commented. “It could have been due to simple statistical error since there were few cases of GC. On the other hand, it may be that the intense inflammatory response that happens with GC assists with HPV clearance.”

While persistence of HPV 16/18 was associated with progression, 55.1% of the subjects with HPV 16/18 showed clearance by 3 years. Therefore, “A single HPV 16/18 testing does not predict outcome,” Dr. Moscicki stressed. A positive HPV 16/18 test at the time of diagnosis was not significant in the multivariate analysis, she explained.

“In summary,” Dr. Moscicki and her colleagues conclude, “our data show that CIN 2 commonly regresses spontaneously in adolescents and young women, supporting the conservative approach in observing young patients with CIN 2.”

Obstet Gynecol 2010;116:1373-1380.