Many women of childbearing age have had colposcopy and TCT, and some have had further biopsies. The test report for some of these people will show the result CIN. So what is CIN? CIN, cervical intraepithelial neoplasia, is a precancerous lesion closely related to cervical invasive cancer. CIN is closely correlated with HPV infection, and the vast majority of patients with CIN, have HPV infection. However, lesions induced by this single viral infection factor rarely develop into invasive carcinoma. That is to say, HPV infection mostly cannot persist and can often subside naturally without clinical symptoms. In contrast, lesions induced by multiple factors have cancerous potential and may develop into invasive carcinoma. That is, when HPV infection persists and there are factors such as smoking, sexual disorders, having sexually transmitted diseases and using contraceptive pills, the risk of developing from CIN to cervical invasive cancer is greater. CIN is classified into 3 grades, namely CIN1, CIN2 and CIN3. CIN1 can mostly regress spontaneously, therefore, for those who do not have obvious lesions and can seek medical attention at any time, they can be treated as inflammatory disease first, with regular colposcopy and TCT, and biopsy again if necessary. CIN2 and CIN3 should generally be treated surgically with cervical cerclage or conization. Those who are older and do not need to have children can also undergo total hysterectomy if they are CIN3.