Joint Frailty Modeling for Multiple Recurrent Eventsand Its Application in Patients with Breast Cancer

Aims :

Breast cancer is one of the most prevalent recurrent cancers among women. Several factors affecting multiple recurrences of this disease have been studied and recognized in various studies. One of the various types of models used to analyze recurrent events considering the lack of homogeneity among patients is a frailty model. The aim of the present study was to investigate joint frailty modeling for multiple recurrent events and its application in patients with breast cancer.

Materials and Methods:

 In this survival and retrospective analysis, 342 patients with breast cancer whose records were registered for follow-up in a Cancer Research Center at Shohadaye Tajrish Hospital, Tehran, Iran, from 2006 to 2015, were selected. The sampling method was purposive. These patients were monitored for at least 6 months after diagnosis and their latest statuses. For data analysis, the joint frailty survival model was used. Running the model and conducting the data analysis were performed by codes in Frailtypack using R 3.4.1 statistical software. 

Findings:

Three-year and five-year survival rates for the patients were 0.79 and 0.68, respectively. The risk of multiple recurrences (Local and metastases) increased for the patients with tumor grades greater than I. It was found that when neglecting the relationship between multiple recurrences in the patients with breast cancer, a significant correlation was missed.

Conclusion :

With regard to the significant variance of the frailty component of the metastases event, the patients with the same predictive variables are prone to different levels of metastases risk.