Outcomes in women with invasive ductal or invasive lobular early stage breast cancer treated with anastrozole or exemestane in CCTG (NCIC CTG) MA.27.

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 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.

• Authors: K Strasser-Weippl, G Sudan, R Ramjeesingh, L E Shepherd, J O'Shaughnessy, W R Parulekar, P E R Liedke, B E Chen, P E Goss
• Journal: European journal of cancer (Oxford, England : 1990) (Eur J Cancer) Vol. 90 Pg. 19-25 (02 2018) ISSN: 1879-0852 [Electronic] England
• PMID: 29274617 (Publication Type: Clinical Trial, Phase III, Journal Article, Multicenter Study, Randomized Controlled Trial, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Chemical References

• Androstadienes
• Antineoplastic Agents
• Nitriles
• Triazoles
• Anastrozole
• exemestane

Topics

• Adult
• Aged
• Aged, 80 and over
• Anastrozole
• Androstadienes (therapeutic use)
• Antineoplastic Agents (therapeutic use)
• Breast Neoplasms (drug therapy, mortality)
• Carcinoma, Ductal, Breast (drug therapy, mortality)
• Carcinoma, Lobular (drug therapy, mortality)
• Disease-Free Survival
• Female
• Humans
• Middle Aged
• Nitriles (therapeutic use)
• Treatment Outcome
• Triazoles (therapeutic use)