p16INK4a expression as a potential marker of low‐grade cervical intraepithelial neoplasia progression

To evaluate p16^INK4a immunoexpression in CIN1 lesions looking for differences between cases that progress to CIN2/3 maintain CIN1 diagnosis, or spontaneously regress. Seventy‐four CIN1 biopsies were studied. In the follow‐up, a second biopsy was performed and 28.7% showed no lesion (regression), 37.9% maintained CIN1, and 33.4% progressed to CIN2/3. Immunostaining for p16^INK4a was performed in the first biopsy and it was considered positive when there was strong and diffuse staining of the basal and parabasal layers. Pearson's chi‐square was used to compare the groups (p ≤ 0.05). The age of the patients was similar. There was no significant difference in p16^INK4a immunoexpression in the groups, however, statistical analyses showed a significant association when only the progression and regression groups were compared (p = 0.042). Considering p16^INK4a positivity and the progression to CIN2/3, the sensitivity, specificity, positive, and negative predictive values in our cohort were 45%, 75%, 47%, and 94%, respectively. We emphasize that CIN1 with p16^INK4a staining was associated with lesion progression, but the sensitivity was not high. However, the negative predictive value was more reliable (94%) and p16^INK4a may represent a useful biomarker that can identify CIN1 lesions that need particular attention, complementing morphology.