Abstract P2-14-08: Use of systemic therapy for early stage breast cancer in older adults: Results from the Bridging the Age Gap study

Abstract

Abstract Background: Older patients with early breast cancer (EBC) are a heterogenous population which is often treated less aggressively than their younger counterparts. This may lead to increased variance in the use of adjuvant systemic therapy and consequent inferior outcomes.Use of adjuvant systemic therapy in a population of older EBC patients was evaluated within a large UK prospective multicentre cohort study (Bridging the Age Gap). Methods: A prospective, multicentre, observational study of women aged over 70 with EBC was conducted between 2013 and 2018 at 57 Institutions in the UK. Women were recruited at diagnosis and baseline demographics, patient and tumour characteristics, treatment details, adverse events and quality of life were recorded for up to 24 months. Simple statistics, Fisher’s exact test, chi-squared and Cox regression were used as appropriate. The interaction between systemic therapy use, tumour and patient characteristics and survival and toxicity outcomes were evaluated using uni- and multivariate analysis and propensity score matching. Results: 3,649 patients were enrolled in the study of whom 3416 were eligible. 2,816 (82.4%) underwent surgery within 6 months of diagnosis. Of those patients undergoing surgery, 2,554 (90.7%) had Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) 0-1 and 2,710 (96.2%) had a modified Charlson comorbidity Index ≥2. Activities of Daily Living (ADL) were impaired in 568 cases (20.2%) and Instrumental Activities of Daily Living (IADL) in 498 (17.7%). 1,876 patients (66.2%) had normal Mini-Mental State Examination (MMSE). In the overall population, 382 patients (13.6%) received chemotherapy. Its use increased substantially in patients with tumours larger than 50 mm (25.2%), involving axillary lymph nodes (23.6%) and grade 3 (27.4%). Chemotherapy was given in 34.6% of patients with ER-negative and in 47.76% of patients with HER2-positive disease. However, its use decreased with age from 20.7% in patients aged 70-74 to 3.6% in those aged ≥80. Chemotherapy was used in 14.1% of patients with ECOG PS 0-1, 15.6% of those with normal ADL score, 15.6% of those with normal IADL score and 14.2% of those with normal MMSE.Of the total cohort of 3416 women, 1520 (44.5%) had high recurrence risk cancer and 381 (25.0%) patients subsequently underwent chemotherapy. The chemotherapy and no chemotherapy groups differed significantly in age, fitness and frailty. Unadjusted all cause mortality was 17.6% for no chemotherapy and 9.3% for chemotherapy patients. Baseline variation in health status was propensity score adjusted yielding a matched cohort of 381 no chemotherapy and 225 chemotherapy patients. Matched all cause mortality was 10.8% for no chemotherapy versus 10.7% for chemotherapy. EBC specific mortality was 7.0% for no chemotherapy and 8.1% for chemotherapy patients. These data suggest that chemotherapy confers little survival benefit in this age group. Conclusions: The use of chemotherapy in this population is consistent with published data, with a substantial proportion of fit older patients with high-risk breast cancer not receiving it. However, undertaking a matched analysis of outcomes suggests that there is little benefit in this age group at short follow-up. Incorporating geriatric assessment may better inform the management of these complex patients in a multidisciplinary setting. Table 1 - Chemotherapy use based on tumour and patient characteristics.CharacteristicsChemotherapy givenYesNoN (%)N (%)Tumour size (mm)≤2093 (7.3)1,182 (92.7)21-50 233 (17.7)1,085 (82.3)≥5050 (25.2)148 (74.7)Unknown6 (24.0)19 (76.0)pN stagepN0 (incl. micrometastases)174 (9.0)1,751 (91.0)pN1116 (18.7)504 (81.3)pN254 (33.5)107 (66.5)pN334 (40.5)50 (59.5)Unknown4 (15.4)22 (84.6)Grade15 (1.3)384 (98.7)2129 (8.6)1,378 (91.4)3239 (27.4)632 (72.6)Unknown9 (18.4)40 (81.6)HistologyInvasive ductal carcinoma287 (14.4)1,701 (85.6)Invasive lobular carcinoma59 (14.6)345 (85.4)Tubular0 (0.0)31 (100.0)Mucinous2 (2.5)78 (97.5)Other29 (10.1)257 (89.9)Unknown5 (18.5)22 (81.5)Receptor statusER statusPositive247 (10.3)2,144 (89.7)Negative129 (34.6)244 (65.4)Unknown6 (11.5)46 (88.5)HER2 statusPositive160 (47.8)175 (52.2)Negative210 (9.1)2,095 (90.9)Inconclusive4 (17.4)19 (82.6)Unknown8 (5.2)145 (94.8)Oncotype DX testYes6 (14.6)35 (85.4)No376 (13.5)2,399 (86.4)Age70-74242 (20.7)928 (79.3)75-79120 (13.4)777 (86.6)80-8418 (3.6)487 (96.4)≥851 (0.4)11 (91.7)ECOG Performance status0301 (15.5)1,646 (84.5)160 (9.9)547 (90.1)23 (3.7)77 (96.2)32 (5.6)34 (94.4)40 (0.0)1 (100.0)Unknown16 (11.0)129 (89.0)ADL score20309 (15.6)1,669 (84.4)1932 (10.6)270 (89.4)≤1815 (5.6)251 (94.4)Unknown26 (9.6)244 (90.4)IADL score8315 (15.6)1,699 (84.4)727 (10.8)222 (89.2)≤67 (2.8)242 (97.2)Unknown33 (10.9)271 (89.1)Modified Charlson comorbidity index0-10 (0.0)0 (0.0)≥2371 (13.7)2,339 (86.3)Unknown11 (10.4)95 (89.6)MMSE>24267 (14.2)1,609 (85.8)20-247 (17.5)33 (82.5)<204 (12.9)27 (87.1)Unknown104 (12.0)765 (88.0) Citation Format: Nicolò Matteo Luca Battisti, Alistair Ring, Mike Bradburn, Lynda Wyld, Age Gap Trial Steering Group. Use of systemic therapy for early stage breast cancer in older adults: Results from the Bridging the Age Gap study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-14-08.