In the Swedish organised cervical screening program precursors of cervical cancer are detected and treated. Most precursor lesions detected by screening heal spontaneously. Those who progress do it slowly. There are three levels from light; CIN1, moderate; CIN2 to severe; CIN3. Women with CIN3 are always treated, regardless of age, according to current clinical guidelines. Women with CIN2 who are below the age of 25 years are offered active expectance for up to two years because there is good evidence that they will spontaneously heal their lesions (regression) in 40-70% of the cases during that time.