CIN stands for cervical intraepithelial neoplasia, which means pre-cancerous cells found on the surface of the cervix. The cells are found by cervical screening with either a cervical smear test or liquid based cytology. The cell changes can be classed as CIN 1, 2, or 3. The higher the number, the more like cancer cells the abnormal cells are and so treatment is given to remove the cells. CIN 1 often goes back to normal without treatment, but a repeat smear is needed to check that the cells have gone.