Estrogen Receptor and Progesterone Receptor As Predictive Biomarkers of Response to Endocrine Therapy: A Prospectively Powered Pathology Study in the Tamoxifen and Exemestane Adjuvant Multinational Trial

John M. S. Bartlett, Cassandra L. Brookes, Tammy Robson, Cornelis J. H. van de Velde, Lucinda J. Billingham, Fiona M. Campbell, Margaret Grant, Annette Hasenburg, Elysee T. M. Hille, Charlene Kay, Dirk G. Kieback, Hein Putter, Christos Markopoulos, Elma Meershoek-Klein Kranenbarg, Elizabeth A. Mallon, Luc Dirix, Caroline Seynaeve, Daniel Rea

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Purpose

The Tamoxifen and Exemestane Adjuvant Multinational (TEAM) trial included a prospectively planned pathology substudy testing the predictive value of progesterone receptor (PgR) expression for outcome of estrogen receptor-positive (ER-positive) early breast cancer treated with exemestane versus tamoxifen.

Patients and Methods

Pathology blocks from 4,781 TEAM patients randomly assigned to exemestane versus tamoxifen followed by exemestane for 5 years of total therapy were collected centrally, and tissue microarrays were constructed from samples from 4,598 patients. Quantitative analysis of hormone receptors (ER and PgR) was performed by using image analysis and immunohistochemistry, and the results were linked to outcome data from the main TEAM trial and analyzed relative to disease-free survival and treatment.

Results

Of 4,325 eligible ER-positive patients, 23% were PgR-poor (Allred < 4) and 77% were PgR-rich (Allred >= 5). No treatment-by-marker effect for PgR was observed for exemestane versus tamoxifen (PgR-rich hazard ratio [HR], 0.83; 95% CI, 0.65 to 1.05; PgR-poor HR, 0.85; 95% CI, 0.61 to 1.19; P = .88 for interaction). Both PgR and ER expression were associated with patient prognosis in univariate (PgR HR, 0.53; 95% CI, 0.43 to 0.65; P < .001; ER HR, 0.66; 95% CI, 0.51 to 0.86; P = .002), and multivariate analyses (P < .001 and P = .001, respectively). A trend toward a treatment-by-marker effect for ER-rich patients was observed.

Conclusion

Preferential exemestane versus tamoxifen treatment benefit was not predicted by PgR expression; conversely, patients with ER-rich tumors may derive additional benefit from exemestane. Quantitative analysis of ER and PgR expression provides highly significant information on risk of early relapse (within 1 to 3 years) during treatment.

Original languageEnglish
Pages (from-to)1531-1538
Number of pages8
JournalJournal of Clinical Oncology
Volume29
Issue number12
DOIs
Publication statusPublished - 20 Apr 2011

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