Abstract P5-17-04: Metastatic inflammatory breast cancer: Clinical features and outcomes in the national, multicentric, real-life ESME cohort
Authors: Monneur A , Bertucci F , Lardy-Cleaud A , Augereau P , Debled M , Levy C , Mouret-Reynier MA , Coudert B , Mailliez A , Bachelot T , Ferrero J-M , Guiu S , Uwer L , Campone M , Cottu P , Jouannaud C , De la Motte Rouge T , Leheurteur M , Petit T , Pistilli B , Dalenc F , Simon G , Robain M , Viens P , Lerebours F , Gonçalves A 
Published: May 2019

Background:Primary inflammatory breast cancer (IBC) is a rare and aggressive form of breast cancer. Survival of IBC patients has been improved by multimodal therapy. However 5-year overall survival (OS) still remains close to 50-60%, due to high risk of disseminated disease. Given the low incidence, prognosis of metastatic cases stages is poorly described.

Methods:This study aimed to describe OS of IBC (T4d AJCC TNM classification) with upfront or recurrent metastatic disease compared with non-IBC patients in the ESME database (N=16,702 patients). OS was calculated from the diagnosis of metastasis to the date of death (from any cause), or censored to date of latest news. Secondary objectives included progression-free survival (PFS).

Results:From 2008 to 2014, 7,465 patients with diagnosis of MBC and known clinical status of their primary tumor (T) were identified, including 582 IBC (T4d) and 6,883 non-IBC. As expected, metastatic IBC was associated with pejorative features compared to non-IBC, with less hormonal receptors-positive tumors (44% vs 65.6%), more HER2-positive (30% vs 18.6%) or triple-negative (25.9% vs 15.8%) cases (p&lt;0.001), more frequent upfront M1 stage (53.3% vs 27.7%; p&lt;0.001), and shorter median disease-free interval (2.02 years vs. 4.9 years; p&lt;0.001). With a median follow-up of 50.2 months (0-104), median OS was 28.4 [95%CI 24-33.8] versus 37.2 months [95%CI 36.1-38.5] in metastatic IBC and non-IBC cases respectively (p&lt;0.0001, log-rank test). By multivariate Cox model with adjustment for major prognostic factors [including age, disease-free interval, type of relapse, visceral metastases, molecular subtype, grade], OS was significantly shorter in the metastatic IBC group compared with non-IBC group (HR 1.25 [95%CI 1.1-1.4], p=0.0002). Of note, survival of metastatic IBC patients improved over the last years: median OS 24 months [95%CI 20-31.9], 29 months [95%CI 21.7-39.9] and 36 months [95%CI 27.9-NE] if diagnosed before 2011, between 2011 and 2012, or after 2012 respectively (p=0.003). Such improvement was not observed in non-IBC patients. IBC was associated with shorter median PFS under first line systemic treatment compared with non-IBC (7.2 months [95%CI 6.6-8.3] vs 9.5 months [95%CI 9.1-9.8] respectively, p=0.0136). This was maintained in a multivariate Cox model adjusting for same factors as for OS (HR 1.15 [95%CI 1-1.3], p=0.0050).

Compared with non-IBC, synchronous metastatic IBC showed worse median OS and PFS (39.9 months [95%CI 34.2-45.3] vs 48.4 months [95%CI 46.3-50.8], p=0.0035; 10 months [95%CI 8.8-12.7] vs 14.5 months [95%CI 13.6-15.7], p=0.0027, respectively. Similar results were obtained in metachronous metastatic cases (20.01 months [95%CI 17.1-21.2] vs 32.8 months [95%CI 31.5-34.3], p&lt;0.0001; 5.1 months [95%CI 4.1-6] vs 7.9 months [95%CI 7.6-8.3], p&lt;0.0001, respectively).

Conclusion:In this large national and multicentric study, IBC is a major and independent factor associated with adverse outcome in metastatic setting. Of note, the independent adverse impact on PFS identified in this study may suggest a lower sensitivity of metastatic IBC to available therapeutics. However, results seem to improve in the last years. Detailed analysis according to phenotype will be available.

Citation Format: Monneur A, Bertucci F, Lardy-Cleaud A, Augereau P, Debled M, Levy C, Mouret-Reynier MA, Coudert B, Mailliez A, Bachelot T, Ferrero J-M, Guiu S, Uwer L, Campone M, Cottu P, Jouannaud C, De la Motte Rouge T, Leheurteur M, Petit T, Pistilli B, Dalenc F, Simon G, Robain M, Viens P, Lerebours F, Gonçalves A. Metastatic inflammatory breast cancer: Clinical features and outcomes in the national, multicentric, real-life ESME cohort [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-17-04.