Age distribution of HPV genotypes in cervical intraepithelial neoplasia

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.

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.

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.

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.