Changes in cervical dysplasia, carcinoma in situ, and cervical cancer after expanding the National Cancer Screening Program to younger women in Korea.

The National Cancer Screening Program of South Korea for cervical cancer was expanded from women aged ≥30 years to women aged ≥20 years in 2016. This study investigated the effect of this policy on occurrence rates of cervical dysplasia, carcinoma in situ, and cervical cancer in women in their twenties. The National Health Information Database for the years 2012-19 was used. The outcome measures were monthly occurrence rates of cervical dysplasia, cervical carcinoma in situ, and cervical cancer. An interrupted time series analysis was performed to investigate whether the number of occurrences changed after policy implementation. For cervical dysplasia, a pre-intervention decreasing trend of 0.3243 per month (P-value < .0001) was found. The post-intervention trend did not differ significantly, although the slope increased at a rate of 0.4622 per month (P-value < .0001). For carcinoma in situ, a trend of increase at 0.0128 per month (P-value = .0099) was seen before policy implementation. The post-intervention trend did not escalate, but the slope showed an increasing trend of 0.0217 per month (P-value < .0001). For cervical cancer, no significant trend was present before intervention. Occurrences of cervical cancer escalated at a rate of 0.0406 per month (P-value < .0001) after policy implementation, and the slope also showed an increasing trend at a rate of 0.0394 per month (P-value < .0001). Expanding the target population for cervical cancer screening increased detection rates for cervical cancer in women aged between 20 and 29 years.