Cervical sample collection

Our study consisted of 3 groups of patients: 1) the open-population, 2) women with CIN 1 and 3) women with CC. The collection of the samples was conducted from 2015 to 2019. Open-population samples (n = 3000) were obtained from women seeking routine gynaecologic care at the Hospital Regional Valentín Gómez Farias (ISSSTE, Mexico), which receives samples from diverse states of Western Mexico, including Aguascalientes, Colima, Guanajuato, Jalisco, Michoacan and Nayarit. The precancerous lesion samples (n = 77) and cervical cancer samples (n = 96) were collected from women attending the Dysplasia Clinic and Oncology Service, respectively, at UMAE Hospital de Gineco-Obstetricia Centro Médico Nacional de Occidente (CMNO, IMSS). We exclusively included women who attended gynaecological services for the first time who did not have any prior treatment and whose diagnosis was confirmed by histopathology. Cases with insufficient data (without age or diagnosis confirmation) or poor DNA quality or quantity were excluded. Cervical samples were collected during gynaecological examination by inserting a cytobrush into the endocervical canal and rotating it for 3–5 full turns. Samples were placed in transport medium solution (Thin Prep PreservCyt® solution, Cat. No. 70097–002; Hologic, Bedford, MA, USA). All participants provided written informed consent prior to sample collection. All participant data were managed confidentially. This study was approved by the Ethics and Research Committees of the Instituto Mexicano del Seguro Social (IMSS), CONBIOETICA-09-CEI-009-20,160,601 with the registration numbers R-2014-785-036 and R-2018-785-147 and from the ISSSTE Research Committee (registration number ISSSTE/CEI/2013/080).