EFFECT OF SELECTED PROGNOSTIC AND RISK FACTORS ON SURVIVAL OF WOMEN WITH BREAST CANCER IN GEORGIA

According to the population-based cancer registry data in Georgia, the incidence rate of breast cancer per 100000 women was 90.6 in 2016. The aim of this study is to explore the effects of risk and prognosis factors on survival of female invasive breast cancer patients in Georgia. Cancer survival analysis was conducted, it is based on retrospective study of Georgian cancer registry data. Almost all breast cancer cases who were diagnosed and histologically confirmed during the period of 2006-2015 and are recorded in the cancer registry system, were included in the study. From factors, associated with prognosis of disease and are considered as risk and prognosis factors, demographic (age at diagnosis, place of residence) and histopathology factors (stage at diagnosis and tumor cell differentiation grade) were included in the study. Survival status (alive, dead or censored) was used as the dependent (response) variable. As the starting point of time for estimating survival of patients was defined the date of diagnosis. Patients' observation period included the time from the date of diagnosis to the last follow-up (31ST December 2016) for those who was alive by the end of the study, and the date of death (end-point) for those who died during the study period. Any cause of death of cancer patients was considered as the end point. That means the overall (and not breast cancer specific) survival rate response to predictor factors was estimated in the study. Cox proportional hazard regression model was constructed to analyze the effect of all risk and prognosis factors and calculate the hazard ratio (HR) for mortality and 95% Confidence Interval (95% CI). A p value < 0.05 was considered as statistically significant. Total number of breast cancer cases enrolled in the study is 3852, age range from 21 to 80 years. We have found that cancer diagnosed between 41-59 years of age had a lower death hazard (HR=1.45, p=0.04) compared to cancer detected over 60 years of age (HR=2.40, p<0.01). There were significant differences (p<0.01) in terms of survival between patients, detected at different stages: the hazard ratio of death for cancer patients diagnosed at the second, third and fourth stages was 2.25, 4.04, and 10.43 accordingly. The study results showed that the moderately differentiated tumor had better survival chance (HR=1.35, p=0.44), than those with poorly differentiated (HR=2.37, p=0.03), and undifferentiated cancers (HR=5.19, p=0.01). Patients living in regions of Imereti (HR=1.40, p=0.02), Adjara (HR=1.37, p=0.07), and Guria (HR=1.30, p=31), had higher risk of mortality than residents of Tbilisi, while living in Shida Kartli (HR=0.59, p=0.01) region had statistically significant effect on better survival. Breast cancer survival dissimilarities among the regions of Georgia could be explained by detection of cancer at different stages and non-standard approaches to cancer management. Some risk and prognosis factors, such as the demographic (age and place of residence) and histopathology (stage at diagnosis and tumor cell differentiation grade) factors have impact on survival of the female invasive breast cancer patients, moreover, this effect mainly is statistically significant.