Evaluation of the possible protective effect of the copper intrauterine device and the levonorgestrel intrauterine system on the risk of precursor lesions and cervical cancer

We estimate that we will have 36,469 cases seen between 1999 and 2017. All women who had an abnormal cytological examination (cervical cancer or precursor lesions) during follow-up at the outpatient clinic will be considered as cases. This universe is estimated to be approximately 1,000 women based on the information system of the Cytopathology Laboratory of CAISM, UNICAMP.

Women selected at the same outpatient clinic but with normal cytological tests throughout the follow-up period will be considered as controls. The total number of controls will be the same as the total number of cases. For pairing cases and controls, the criterion adopted will be the year of the cytological examination with abnormal results (cases), i.e., for each abnormal cytological examination, a woman will be selected with a normal cytological examination performed in the same year, immediately preceding and following the case.