Abnormal cells are found on the surface of the cervix. CIN is usually caused by certain types of human papillomavirus (HPV) and is found when a cervical biopsy is done. CIN is not cancer, but may become cancer and spread to nearby normal tissue. It is graded on a scale of 1 to 3, based on how abnormal the cells look under a microscope and how much of the cervical tissue is affected. For example, CIN 1 has slightly abnormal cells and is less likely to become cancer than CIN 2 or CIN 3. Also called cervical intraepithelial neoplasia.