Spontaneous regression of cervical intraepithelial neoplasia 3 in women with a biopsy—cone interval of greater than 11 weeks

BACKGROUND: Although there is broad consensus that only a subset of CIN3 will progress to cancer, there is currently no surefire way to predict which CIN3 will regress. Understanding the natural history of CIN3 is important, and finding markers for progression or regression could improve treatment strategies. According to the guidelines of the American Society for Colposcopy and Cervical Pathology of 2006, positive CIN3 p16 in women should be managed with excisional treatment (LEEP). For ethical reasons we cannot fail to treat women with CIN3 in order to study their regression capacity so we conducted a retrospective study to evaluate the regression rate of CIN3 diagnosed with a biopsy by studying the histological result of the cone removed by LEEP. We also investigated age, HPV genotypes and biopsy-cone interval distance as possible regression factors. METHODS: We selected 171 women with a histological diagnosis of positive CIN3 p16 as an entry criterion. All patients underwent LEEP / biopsy. A histological diagnosis of the cone of CIN3 or higher was considered as persistence or progression, the diagnosis of CIN1 or lower was considered as regression of the lesion. We used out a logistic model to study the probability of spontaneous regression of CIN3 as a function of the patient’s age, the time elapsed between the biopsy and the cone (in weeks) and the HPV genotype. RESULTS: We found that the spontaneous regression rate of CIN3 was 15,8%, which was strongly associated with the biopsy-cone interval > 11 weeks. Genotype 16, the most represented, was present both in cases of regression (77.8%) and in persistence (83.3%). Regarding age, the estimated odds ratio of the probability of observing a regression in women over 25 years of age was 0.0045 times that of women under 25 years of age (CI: 0.00020, 0.036). Neither age nor viral genotype are significant as predictors of regression. CONCLUSION: To wait at least 11 weeks from the biopsy before subjecting the woman to LEEP could prevent unnecessary LEEP procedures, considering also that from CIN3 to carcinoma it takes years before the neoplastic transformation takes place. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12885-022-10179-1.