De-escalation of chemotherapy in elderly women using a 70-gene platform: Comparison of the MINDACT study with a real-world study in the Brazilian population (AGEMA-BRA).

Abstract

e12568 Background: The application of genetic signatures can contributes to determine a less toxic treatment in ederly women with luminal biological profile tumors, where toxicity is less tolerated and with a higher risk of fatal outcomes by therapy. The MINDACT study evaluated this population using MammaPrint, but patients over 70 years of age were poorly represented, corresponding only to 0.8% of the patients evaluated (56 of 6693 patients), and only 26 patients with high clinical risk. Objective: The aim of this study was to verify the possibility of de-escalation of systemic treatment with the use of MammaPrint genetic signature in elderly women, comparing the prevalence of data from the MINDACT study population with a cohort of Brazilian patients submitted to the examination (AGEMA-BRA). Methods: Cross-sectional study comparing the prevalence of low and high risk genomic patients in a population with luminal profile breast carcinoma with high clinical risk in MINDACT study populations with a Brazilian cohort older than 70 years, evaluated by the genetic signature MammaPrint, between 2016 and 2020. Descriptive analysis of data with estimation of simple and relative frequencies of variables in relation to low and high risk classification and study populations (AGEMA-BRA and MINDACT). Then, the chi-square test was used to verify the differences between the proportions. To measure the intensity of differences/associations, relative risks (RR) and their 95% confidence intervals (95% CI) were calculated. The tests were considered significant when p <0.05. Results: From a database of 950 patients submitted to MammaPrint analysis from 2016 to 2020. The population older than 70 yo (71-84 yo) at the time of diagnosis was represented by 89 patients (9.4%), all with high clinical risk. Of these patients, 54 (60.7%) corresponded to low genomic risk and 35 (39.3%) at high genomic risk. The comparative analysis between the prevalence of the Brazilian population and the MINDACT study, in which the low genomic risk was 61.5% and the high genomic risk 38.5%, showed no statistical significance (RR 0.98 (0.69-1.39) p= 0.936). Conclusions: The comparative analysis of the prevalence among the results of MammaPrint in the MINDACT study and in a cohort of Brazilian women (AGEMA-BRA) in the population older than 70 years, showed no statistical difference. With the confirmation of MINDACT data in this age group in a three-fold larger cohort (AGEMA-BRA), it is inferable that, although the low representativeness in the studies, the genetic signature MammaPrint can be applied in the elderly woman. Evaluation of outcomes regarding relapse-free survival and overall survival, an ongoing study, is necessary to confirm the data obtained.