Abstract P2-06-02: De novo and relapsed metastatic breast cancer: Presentation and survival changes over time 1990-2009
Authors: Malmgren JA , Atwood MK , Kaplan HG 
Published: March 2017

Abstract
Background: De novo stage IV and relapsed stage IV metastatic breast cancer (MBC) may present with different biology and respond differentially to treatment. De novo stage IV patients are treatment naive which may confer a survival advantage. Prior radiation and chemotherapy treatment for relapsed stage IV (rMBC) patients reduces available treatment options and may confer a survival disadvantage. The possible survival differences have not been adequately studied.
Methods: A retrospective cohort study of de novo and relapsed stage IV MBC patients from a dedicated institutional BC registry database, years 1990-2009 [invasive BC N = 7653, MBC N=1077 (de novo = 221, relapsed = 856)]. Relapsed stage IV MBC (rMBC) patients were identified by continuous annual follow up of stage I-III patients for distant metastases (M1). De novo stage IV MBC was identified as such at diagnosis using AJCC 7 diagnostic criteria (Any T, Any N, M1). Chi square tests, Kaplan Meier plots, and Cox regression survival analysis were conducted. Disease specific survival (DSS) interval was time from diagnosis date to breast cancer death for de novo MBC and time from first distant relapse date to breast cancer death for rMBC patients.
Results: De novo MBC incidence was constant at 3% per year over time but rMBC decreased from 17% to 8% (1990-99 to 2000-09, p&lt;.001). Among rMBC cases, percentage of her2-neu (her2) positive cases decreased 16% over time from 1990-99 to 2000-09. With the decrease in her2 positive cases the relative number of hormone receptor-/her2- (triple negative) rMBC cases increased proportionately. MBC average survival was 3.2 years (.01, 19.67) with median de novo survival equal to 3.81 years and median rMBC survival equal to 1.81 years (p&lt;.001). Overall, 5 year DSS among de novo stage IV patients was superior at 43% vs. 21% among rMBC patients (0&lt;.001). Over time de novo stage IV 5 year DSS improved significantly from 31% to 51% (p =.018). rMBC 5 year DSS did not improve over time and appeared to decline but not significantly [1990-99 23%, 2000-09 18%, p = .079]. In Cox regression analysis, factors associated with worse DSS were TN status (RR = 2.20, 95% CI 1.75, 2.75), age 70+ (RR = 2.35, 95% CI 1.73, 3.19), and rMBC vs. de novo MBC (RR = 2.44, 95% CI 1.95, 3.07).
Conclusions: We observed better overall DSS among de novo MBC patients compared to rMBC patients. DSS rates improved over time in de novo MBC but not among the relapsed MBC patients. Overall, better breast cancer specific survival among de novo MBC patients may be related to better response to treatment in therapy naive de novo MBC and use of neoadjuvant therapy methods. It appears the introduction of targeted her2-neu therapy has reduced the number of Her2+ patients with relapsed MBC. Less effective treatment options for de novo and relapsed triple negative BC and BC in the elderly may be responsible for the elevated risk of mortality from MBC observed among TNBC and elderly patients.
Citation Format: Malmgren JA, Atwood MK, Kaplan HG. De novo and relapsed metastatic breast cancer: Presentation and survival changes over time 1990-2009 [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-06-02.