Application of Censored Quantile Regression to Determine Overall Survival Related Factors in Breast Cancer

Background: The occurrence and the mortality related to breast cancer (BC) in Iranian female population has increased over time. Although there are many studies on BC and related risk factors, however, the epidemiological aspects of this melanoma in Iranian females are uncertain. Therefore, the aim of this study was to determine the relationship between demographical and clinical factors on the shape of overall survival (OS) distribution in patients with BC. Methods: This historical cohort study was carried out using data from 522 participants with BC. Data were gathered from medical records of these patients admitted to Mahdieh Oncology Center of Hamadan Province, western Iran, from January 2000 to August 2011. Kaplan-Meier estimator was used to estimate the survival rates and, censored quantile regression (CQR) to provide in-depth insight in the multivariable association between prognosis factors and survival rates. Results: Patients' follow-up ranged from around 3 to 197 months. One-, three-, and five-year survival rates were 90%, 73% and 62.5%, respectively. Results of CQR model showed that change in the age at diagnosis, number of involved lymph nodes and tumor size could significantly change the median and some other quantiles of OS. Conclusions: This study, confirm the importance of early detection of BC and usefulness of CQR because of possible changes in distribution family of survival time.