Survival Analysis of Iranian Patients with Breast Cancer Using Joint Frailty Model with a Cure Rate

Background: Breast cancer is a common disease among women around the world. In Iran, it is the most prevalent cancer diagnosed in women. The objective of this study was to assess the cure rate of patients and the associated risk factors. Method: A retrospective cohort study was conducted on 446 patients with breast cancer admitted to the Shahid Ramezanzadeh Radiotherapy Center. Using R 3.2.2 software, the Kaplan-Meier curve, log-rank test, and cure joint frailty model were utilized in the analysis. Results: Of the 446 patients, 17.3% died, 20% experienced relapse, and 62.7% were censored. The 1-5-7-year disease-free survival rates were 95.3%, 73.4%, and 69.3%, respectively. In the cure model, stage, involved lymph node, and surgery were statistically significant. In the recurrence model, stage, involved lymph node, lymphovascular invasion, and hormone therapy were statistically significant. In the death model, stage, lymphovascular invasion, and involved lymph node had a statistically significant effect on the survival time. Conclusion: The cure joint frailty model is a good model when there is a high fraction of patients who do not experience any recurrence or death. In addition, this model allows for the separate estimation of explanatory variable effect on recurrence, death, and cure. The findings of our study can be conducive to preventing the unfavorable effects of breast cancer and increasing the survival of patients.