Breast cancer is the most commonly diagnosed cancers worldwide. It is a cancer that develops from breast tissue and most common invasive cancer in women. Recurrent events data have been increasingly important in clinical studies where individuals experience an event more than once and it is a major clinical indicator, which represents the principal cause of breast cancer-related deaths. The aim of the study was to investigate determinants of the recurrence of breast cancer.
To reach the aim, 421 women with breast cancer were included in the study based on data taken from medical record card of patients enrolled starting from 1st January 2013 to 30th January 2019. A retrospective study has been applied to obtain data on women breast cancer that recorded in oncology department of Tikur Anbessa specialized Hospital. Unmeasured shared similarities due to the impact of multiple events were modeled using a random effect. Cox-PH model and Shared frailty model were used to identify which factor was significantly affecting the recurrence of breast cancer.
From the total of 997 recurrent events, about 609 (61.1%) of them experienced recurrence of breast cancer. The shared log-normal frailty model was chosen as the best fit for this breast cancer data set based on the value of Likelihood cross validation criterion. From the result of shared log-normal frailty model age, stage of breast cancer, tumor size, histology grade, breast feeding and oral contraceptives were significantly associated with recurrence of women breast cancer.
generally shared log-normal frailty model shows that the stage (II, III, IV), tumor size ((3-5) cm, >5 cm), histology grade (poorly differentiated) and oral contraceptive were significantly increases the risk of recurrence of breast cancer. While, breast feeding was significantly decreases the risk of recurrence of breast cancer. It is recommended that policy maker, ministry of health and Tikur Anbessa Specialized Hospital are expected to make interventions based on these hazardous groups for recurrence of breast cancer.