At what age is Cervical intraepithelial neoplasia (CIN) most commonly diagnosed?

Cervical intraepithelial neoplasia (CIN) is most commonly diagnosed in women in their 20s, primarily due to the patterns of cervical screening and the age-related incidence of human papillomavirus (HPV) infections, which are a significant risk factor for the development of CIN. The peak prevalence of CIN, particularly CIN 2 and CIN 3 (which are the more severe forms), occurs in this age group as women are frequently screened through Pap tests starting in their early 20s.

Moreover, HPV infections are very common among younger women due to increased sexual activity and a higher number of sexual partners associated with this age group. Regular screening programs and awareness have also led to earlier detection of CIN in women in their 20s, making this age the most common for diagnosis.

While other age groups may face risks associated with CIN, such as women aged 30-40 and women over 50, they do not represent the peak incidence of diagnosis like women in their 20s do. Additionally, the prevalence of high-grade lesions in older populations tends to be lower, as many women clear HPV infections naturally or may have already undergone screening that prevented progression to higher grades of CIN.