K Strasser-Weippl1, G Sudan2, R Ramjeesingh3, L E Shepherd4, J O'Shaughnessy5, W R Parulekar4, P E R Liedke6, B E Chen4, P E Goss7. 1. Wilhelminen Hospital, Vienna, Austria. Electronic address: kathrin.strasserweippl@gmail.com. 2. Southlake Regional Health Centre, Ontario, Canada; Canadian Cancer Trials Group, Queen's University, Kingston, Ontario, Canada. 3. Nova Scotia Cancer Centre, NS, Canada; Dalhousie University, NS, Canada. 4. Canadian Cancer Trials Group, Queen's University, Kingston, Ontario, Canada. 5. Baylor University Medical Center, Texas Oncology, US Oncology, Dallas, TX, USA. 6. Mae de Deus Cancer Institute, Porto Alegre, RS, Brazil; Servico de Oncologia, Hospital de Clinicas de Porto Alegre, Porto Alegre, RS, Brazil. 7. Massachusetts General Hospital Cancer Center, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
Abstract
BACKGROUND:Histological subtype, (invasive ductal breast cancer (IDBC)/invasive lobular breast cancer (ILBC)), might be a marker for differential response to endocrine therapy in breast cancer. METHODS: Clinical trial MA.27 compared 5 years of adjuvant anastrozole or exemestane in postmenopausal patients with hormone receptor positive early breast cancer. We evaluated IDBC versus ILBC (based on original pathology reports) as predictor for event-free survival (EFS) and overall survival (OS). RESULTS: A total of 5709 patients (5021 with IDBC and 688 with ILBC) were included (1876 were excluded because of missing or other histological subtype). Median follow-up was 4.1 years. Overall, histological subtype did not influence OS or EFS (HR (hazard ratio) 1.14, 95% confidence interval (CI) [0.79-1.63], P = 0.49 and HR 1.04, 95% CI [0.77-1.41], P = 0.81, respectively). There was no significant difference in OS between treatment with exemestane versus treatment with anastrozole in the IDBC group (HR = 0.92, 95% CI [0.73-1.16], P = 0.46). In the ILBC group, a marginally significant difference in favour of treatment with anastrozole was seen (HR = 1.79, 95% CI [0.98-3.27], P = 0.055). In multivariable analysis a prognostic effect of the interaction between treatment and histological subtype on OS (but not on EFS) was noted, suggesting a better outcome for patients with ILBC onanastrozole (HR 2.1, 95% CI [0.99-4.29], P = 0.05). After stepwise selection in the multivariable model, a marginally significant prognostic effect for the interaction variable (treatment with histological subtype) on OS (but not on EFS) was noted (Ratio of HR 2.1, 95% CI [1.00-4.31], P = 0.05). CONCLUSION: Our data suggest an interaction effect between treatment and histology (P = 0.05) on OS. Here, patients with ILBC cancers had a better OS when treated with anastrozole versus exemestane, whereas no difference was noted for patients with IDBC. CLINICAL TRIAL INFORMATION: NCT00066573. Crown
RCT Entities:
BACKGROUND: Histological subtype, (invasive ductal breast cancer (IDBC)/invasive lobular breast cancer (ILBC)), might be a marker for differential response to endocrine therapy in breast cancer. METHODS: Clinical trial MA.27 compared 5 years of adjuvant anastrozole or exemestane in postmenopausal patients with hormone receptor positive early breast cancer. We evaluated IDBC versus ILBC (based on original pathology reports) as predictor for event-free survival (EFS) and overall survival (OS). RESULTS: A total of 5709 patients (5021 with IDBC and 688 with ILBC) were included (1876 were excluded because of missing or other histological subtype). Median follow-up was 4.1 years. Overall, histological subtype did not influence OS or EFS (HR (hazard ratio) 1.14, 95% confidence interval (CI) [0.79-1.63], P = 0.49 and HR 1.04, 95% CI [0.77-1.41], P = 0.81, respectively). There was no significant difference in OS between treatment with exemestane versus treatment with anastrozole in the IDBC group (HR = 0.92, 95% CI [0.73-1.16], P = 0.46). In the ILBC group, a marginally significant difference in favour of treatment with anastrozole was seen (HR = 1.79, 95% CI [0.98-3.27], P = 0.055). In multivariable analysis a prognostic effect of the interaction between treatment and histological subtype on OS (but not on EFS) was noted, suggesting a better outcome for patients with ILBC on anastrozole (HR 2.1, 95% CI [0.99-4.29], P = 0.05). After stepwise selection in the multivariable model, a marginally significant prognostic effect for the interaction variable (treatment with histological subtype) on OS (but not on EFS) was noted (Ratio of HR 2.1, 95% CI [1.00-4.31], P = 0.05). CONCLUSION: Our data suggest an interaction effect between treatment and histology (P = 0.05) on OS. Here, patients with ILBC cancers had a better OS when treated with anastrozole versus exemestane, whereas no difference was noted for patients with IDBC. CLINICAL TRIAL INFORMATION: NCT00066573. Crown
Authors: Jason A Mouabbi; Amy Hassan; Bora Lim; Gabriel N Hortobagyi; Debasish Tripathy; Rachel M Layman Journal: Breast Cancer Res Treat Date: 2022-03-26 Impact factor: 4.872