Age distribution of HPV genotypes in cervical intraepithelial neoplasia

Objective: Recent data showed that HPV16 infections in young women can lead to CIN3 formation very quickly and questioned the common assumption that invasive cervical cancer develops through slowly progressing pre-cancer lesions, CIN1, CIN2 and CIN3. The aim of the study is to compare the age distribution of HPV 16/18 related and HPV16/18 not related CIN. Methods: We used the data generated from the clinical use of HPV genotyping (LINEAR ARRAY, Roche Diagnostics). Patients were grouped on the basis of histology, CIN1 vs. CIN2+ and on HR-HPV genotype status. Results: The probability to develop a CIN2+ seemed to decrease with age in patients infected with HR-HPV genotype 16/18 while the inverse effect was observed in CIN2+ patients who were HR-HPV positive but HPV16/18 negative (Chi-square test, p^trend = 0.01). Only in HR-HPV positive but HPV 16/18 negative patients, a relative reduction of CIN1 vs. CIN2+ was observed with increasing age (Cochran-Armitage test, p ^trend = 0.01); finally, in HR-HPV non-16/18 infected patients only a statistically significant difference in mean age between CIN1 and CIN2+ patients below age 35 was observed. Conclusions: Besides the limitations of the present cross-sectional analysis, these data suggest a genotype specific natural history of cervical cancer precursors development: one type, more frequent, HPV16/18 related, which develops quick and early in life; another one, non-16/18 HR-HPV related, which develops later, slowly, through low- to high-grade lesions. If confirmed, this hypothesis could influence screening policies, especially in the vaccinated population.