Abstract P3-12-15: Clinical characteristics, treatment patterns, and survival outcomes in women with early triple-negative (TN) or hormone receptor-positive/human epidermal growth factor receptor-2 negative (HR+/HER2−) breast cancer (BC) in the real-world (RW) setting
Authors: Gogate Anagha , Crosbie Amanda , Le Trong Kim , Zhang Ying , Das Rolee , Davis Catherine 
Published: March 2022

Background: BC remains the most commonly diagnosed cancer for women. TNBC is an aggressive form with a poorer prognosis compared with other subtypes. Neoadjuvant therapy (NAT) is the standard-of-care approach to shrink tumors in the breast and axilla and to improve patient outcomes. Few RW studies exist of US patients with early BC (eBC); this study aimed to describe clinical parameters by receipt of systemic therapy and to assess overall survival (OS) and progression-free survival (PFS) after NAT and adjuvant therapy (AT) in women with early HR+/HER2− or TNBC using RW evidence in the US. Methods: This retrospective observational study used the Flatiron Health nationwide electronic health record-derived de-identified database, including women ([pts], age ≥18 years) diagnosed with early HR+/HER2− BC or TNBC between 01/01/2011 and 05/31/2018. The primary outcome was to describe pt demographics, clinical characteristics, and treatment patterns. Secondary outcomes included OS and PFS. Results: Of the pts identified for inclusion (N = 5,299), 13.3% (n = 707) were diagnosed with early TNBC and 86.7% (n = 4,592) with HR+/HER2− eBC, of whom 34.7% (n = 245) and 10.9% (n = 502), respectively, did not receive systemic therapy (Table). Systemically treated pts with TNBC vs HR+/HER2− tended to be younger (59.0 years vs 64.0 years); were represented by a higher proportion of Black women (18.0% vs 7.2%); had a greater proportion presenting with invasive ductal carcinoma (IDC) (91.6% vs 78.2%); had a higher proportion with progression to metastasis (19.0% vs 5.7%) and presented with a more aggressive disease (Grade 3) at diagnosis (79.0% vs 18.4%). Most pts (98.4%) received surgery, predominantly breast-conserving surgery (BCS; unilateral lumpectomy: 62.8%); however, 17.8% received bilateral mastectomies. Overall, 9.1% of pts received NAT. More pts with TNBC vs HR+/HER2− received NAT (34.0% vs 7.9%) and achieved a pathologic complete response (pCR; 36.3% vs 6.2%). Consistent with treatment guidelines, pts with TNBC were treated with chemotherapy (CT)-doublet or single-agent regimens and pts with HR+/HER2− received hormone and CT-based regimens. Duration of NAT was similar for both subtypes (3.3 months) but was shorter for AT in pts with TNBC vs HR+/HER2− (3.4 vs 38.2 months). From initial diagnosis, the 36-month survival probability [standard error] was lower for systemically treated pts with TNBC vs HR+/HER2− (85.7% [1.8%] vs 95.6% [0.3%]) and from start of therapy by line setting (NAT: 80.6% [3.5%] vs 91.9% [1.7%]; AT: 84.7% [2.2%] vs 95.8% [0.4%]). Similarly, the 36-month PFS probability was lower for pts with TNBC vs HR+/HER2− from diagnosis (77.9% [2.1%] vs 93.3% [0.4%]) and from start of therapy by line setting (NAT: 68.7% [4.1%] vs 85.2% [2.1%]; AT: 79.5% [2.5%] vs 93.5% [0.4%]). Conclusion: This analysis of US RWE further confirms early TNBC to be a particularly aggressive form of BC, with poorer survival compared with pts with HR+/HER2− eBC. While these RW data indicate BCS is becoming more routine, almost one-fifth of pts still receive bilateral mastectomies. Overall, these data confirm there remains a high unmet need to reduce the need for aggressive treatments while further improving outcomes in pts with early TNBC and HR+/HER2− BC.

Table: Patient demographics, clinical characteristics, OS and PFSPatient selection criteriaNumber of patients, n (%)SubgroupsEarly HR+/HER2− BC4,592 (86.7)Patients who received systemic therapy4,090 (89.1)Early TNBC707 (13.3)Patients who received systemic therapy462 (65.3)All patients [1] (N = 5,299), n (%)Systemically treated patients with early HR+/HER2− BC (n = 4,090), n (%)Systemically treated patients with early TNBC (n = 462), n (%)Patient demographicsMedian age (years)64.064.059.0RaceBlack or African American449 (8.5)294 (7.2)83 (18.0)White3,602 (68.0)2,835 (69.3)283 (61.3)Asian139 (2.6)111 (2.7)9 (1.9)Hispanic or Latino15 (0.3)12 (0.3)1 (0.2)Clinical characteristicsHistology at initial diagnosisIDC4,222 (79.7)3,197 (78.2)423 (91.6)ILC684 (12.9)612 (15.0)7 (1.5)Infiltrating ductal mixed and infiltrating lobular mixed132 (2.5)108 (2.6)3 (0.6)Mucinous adenocarcinoma97 (1.8)88 (2.2)0 (0.0)Other [2]122 (2.3)63 (1.5)26 (5.6)Unknown/ND42 (0.8)22 (0.5)3 (0.6)Tumor grade at initial diagnosisGrade 11,350 (25.5)1,161 (28.4)5 (1.1)Grade 22,462 (46.5)2,098 (51.3)88 (19.0)Grade 31,374 (25.9)752 (18.4)365 (79.0)Unknown/ND113 (2.1)79 (1.9)4 (0.9)Surgery at initial diagnosisYes5,215 (98.4)4,032 (98.6)450 (97.4)Surgery type [3]Unilateral lumpectomy3,277 (62.8)2,568 (63.7)241 (53.6)Unilateral mastectomy1,168 (22.4)883 (21.9)128 (28.4)Bilateral lumpectomy75 (1.4)61 (1.5)5 (1.1)Bilateral mastectomy927 (17.8)713 (17.7)89 (19.8)Treatment line settingNumber of patients who received NAT481 (9.1)324 (7.9)157 (34.0)Number of patients who received AT4,263 (80.4)3,949 (96.6)314 (68.0)pCR to NATAchieved pCR77 (16.0)20 (6.2)57 (36.3)OSFrom initial diagnosis: survival probability at Month 36, % (SE)94.0 (0.4)95.6 (0.3)85.7 (1.8)From NAT: survival probability at Month 36, % (SE)88.3 (1.6)91.9 (1.7)80.6 (3.5)From AT: survival probability at Month 36, % (SE)94.9 (0.4)95.8 (0.4)84.7 (2.2)PFSFrom initial diagnosis: progression-free probability at Month 36, % (SE)91.3 (0.4)93.3 (0.4)77.9 (2.1)From NAT: progression-free probability at Month 36, % (SE)79.9 (2.0)85.2 (2.1)68.7 (4.1)From AT: progression-free probability at Month 36, % (SE)92.5 (0.4)93.5 (0.4)79.5 (2.5)Duration of treatment, Months (n)Median duration of NAT3.3 (481)3.3 (324)3.3 (157)Median duration of AT35.3 (4263)38.2 (3,949)3.4 (314)[1] All patients includes both patients systemically treated and systemically untreated. [2] Other includes Inflammatory, Papillary, Metaplastic, Medullary and Tubular histologies. [3] Patient may have received more than one surgery. AT, adjuvant therapy; IDC, invasive ductal carcinoma; NAT, neoadjuvant therapy; ND, not documented; SE, standard error.

Citation Format: Anagha Gogate, Amanda Crosbie, Trong Kim Le, Ying Zhang, Rolee Das, Catherine Davis. Clinical characteristics, treatment patterns, and survival outcomes in women with early triple-negative (TN) or hormone receptor-positive/human epidermal growth factor receptor-2 negative (HR+/HER2−) breast cancer (BC) in the real-world (RW) setting [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-12-15.