CIN stands for cervical intraepithelial neoplasia, which means precancerous cells found on the surface of the cervix. The cells are often found by cervical screening. 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. So treatment is given to CIN 2 or 3 to remove or destroy the cells. CIN 1 often goes back to normal without treatment, but a repeat test is needed to check that the cells have gone.