Abstract P6-13-02: Increased mortality risk among elderly patients with early stage triple negative breast cancer who did not receive adjuvant or neoadjuvant therapy
Authors: Satram-Hoang S , Bajaj PS , Stein A , Hoang KQ , Momin F , Cortazar P , Reyes C 
Published: February 2018

Background: Worldwide, breast cancer (BC) is the most frequently diagnosed cancer and the leading cause of cancer death in women. The triple negative (TN) subtype accounts for up to 20% of BC and has a poorer prognosis compared to other subtypes. We set out to evaluate treatment patterns and survival associated with receiving adjuvant or neo-adjuvant therapy in an older, demographically diverse population of patients with TNBC.

Methods: The analysis included 10,694 patients with first primary TNBC from the linked SEER-Medicare database. Patients were diagnosed with Stage I-III disease between January 1, 2001-December 31, 2011, ≥66 years, continuously enrolled in Medicare Parts A and B in the year prior to diagnosis, and underwent breast cancer surgery within 6 months after diagnosis. Unadjusted Kaplan Meier analyses and time-varying Cox proportional hazards regression adjusting for patient characteristics assessed overall survival. Date of last follow-up was December 31, 2013.

Results: There were 4,807 (45%) patients treated with adjuvant/neo-adjuvant chemotherapy and 5,887 (55%) untreated. Treatment rates increased over the study time-period from 45% in 2001 to 52% in 2011 (p&lt;.0001). Compared to treated patients, untreated patients were older (78 vs. 73 years), had earlier stage disease (57% vs. 31% Stage I), lower tumor grade (34% vs. 23% grade 1/2), smaller tumors (57 vs.40% &lt;2cm), poorer performance (13% vs. 6%), higher comorbidity burden (45% vs. 37% NCI Comorbidity Score ≥ 1) and were less likely to receive radiotherapy (47% vs. 65%; p&lt;0.0001). The median unadjusted overall survival was 94.3 months for the overall population and was longer for treated patients (101.5 months) compared to untreated patients (88.4 months; log rank p &lt;.0001). In the adjusted Cox model, there was a 28% higher risk of death in untreated compared to treated patients (HR=1.28; 95% CI=1.19-1.38). The model also showed that as age, stage, tumor size, tumor grade, and comorbidity score increased, mortality risk also significantly increased. Having poor performance indicators was also significantly associated with higher mortality risks, while prior radiotherapy was associated with lower risks.

Conclusions: Although therapy use has increased over time, this large observational study confirmed that 55% of elderly patients with Stage I-III TNBC are not receiving adjuvant/neo-adjuvant therapy following diagnosis. As a result, untreated patients exhibited a significantly elevated risk of death compared to those who received treatment. The results of this study highlight the unmet need in this patient population and provide an important context to optimize disease management in real-world settings.

Citation Format: Satram-Hoang S, Bajaj PS, Stein A, Hoang KQ, Momin F, Cortazar P, Reyes C. Increased mortality risk among elderly patients with early stage triple negative breast cancer who did not receive adjuvant or neoadjuvant therapy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-13-02.