ABSTRACT Objective: To determine what factors are present in the late diagnosis of breast cancer in women treated at the Regional Institute of Neoplastic Diseases "Doctor Luis Pinillos Ganoza ", during 2018. Methods: An observational, descriptive and cross-sectional study was carried out, with a sample consisting of 78 women with breast cancer with late diagnosis (stage III and IV). Variables were studied such as: Age, region of origin, socioeconomic factors, access to health services and previous knowledge about Breast Cancer prevention. For the data collection a survey of 22 questions was used based on the survey prepared by Sara Cecilia Suasnabar Reves of the year 2012. The answers were classified according to this Ordinal scale: Adequate level of knowledge and access to health services (12-17 points), intermediate level (6-11 points) and Low level (0-5 points). The latter being alrea...