2944 - Long Term Outcomes in Women = 70 years old with Early-Stage Breast Cancer as Stratified by EUROPA Trial Eligibility
Presenter(s)
C. Hardy Abeloos1, J. M. Karp2, J. Kim1, F. R. Schnabel3, O. Cahlon4, J. So5, A. Solan6, M. Gemignani1, M. Kwa1, and N. K. Gerber4; 1NYU Grossman School of Medicine, New York, NY, 2NYU Langone Medical Center, New York City, NY, 3New York University School of Medicine, New York, NY, 4New York University Grossman School of Medicine, Department of Radiation Oncology, New York, NY, 5Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada, 6NYU Grossman School of Medicine, New York City, NY
Purpose/Objective(s): The ongoing EUROPA trial is assessing the effectiveness of single modality endocrine therapy (ET) vs radiation therapy (RT) in women = 70 years old with stage I hormone-receptor (HR) positive breast cancer. Beyond age, stage, and subtype, the trial further selects for biologically favorable disease by excluding grade 3 tumors if tumor size 11–19 mm and by selecting for luminal A-like biology defined as estrogen receptor (ER) and progesterone receptor (PR) = 10%, HER2 negative and Ki-67 = 20%.The goal of our study was to determine the proportion of women aged = 70 years old with stage I, HR+/Her2- breast cancer in a prospectively maintained institutional database who would meet these eligibility criteria and compare long term clinical outcomes between eligible and ineligible women.
Materials/Methods: Women aged = 70 years old with pT1N0 HR+/HER2- breast cancer undergoing lumpectomy from 2010 to 2017 were identified from a prospectively maintained database. ET adherence, defined as 5 years of treatment duration, was determined by chart review. Fisher’s exact test and Chi-squared test were used to determine differences between groups. Survival curves were analyzed by Kaplan-Meier method, and differences between survival rates were compared by using the log-rank test.
Results: Of 281 women, 191 (68%) patients would have been eligible for the EUROPA trial. Of the 90 patients who are ineligible, 47 had Ki-67 > 20%, 64 had PR < 10%, 5 had ER < 10% and 29 had grade 3 tumors larger than 1 cm. At a median follow up of 8 years, the local recurrence rate, contralateral recurrence rate and distant recurrence rate were 4.7%, 3.1% and 1% in EUROPA-eligible patients vs 10%, 4.4%, 3.3% respectively in ineligible patients (p =0.09, p=0.73, p=0.33, respectively). There was a statistically significant higher local and distant recurrence free survival in patients eligible for the EUROPA trial vs those who were not (HR 0.44; 95% CI 0.22-1.01, p =0.05). Out of the Europa eligible patients, 90 (47.1%) completed 5 years of ET and had RT, 27 (14.1%) had < 5 years of ET and had RT, 15 (7.8%) received ET alone = 5 years, 45 (23.5%) received RT alone and 14 (7.3%) received neither ET nor RT. Out of the entire cohort, 53% of patients completed 5 years of ET, 16% started ET but did not complete 5 years and 31% did not start ET. There was no difference in ipsilateral recurrence rate between patients receiving endocrine therapy alone (n= 1/23) vs RT alone (n=4/59), 4.3% vs 6.8% (p>0.99).
Conclusion: In our cohort of women aged = 70 years old with pT1-2N0 HR+/HER2- breast cancer, only one-third would have been eligible for the EUROPA trial based on biologic selection criteria and only 53% completed 5 years of ET. Local and distant recurrence free survival was statistically significantly higher in EUROPA eligible patients, reinforcing the validity of the biologic selection criteria of the trial. We saw no difference in local recurrence rate between patients treated with ET alone vs. RT alone, though this analysis is limited by small numbers in these subgroups.