Abstract C48: Neoadjuvant endocrine therapy in locally advanced hormone receptor positive (HR+) breast cancer (BC) in a low-resource, middle-income setting (Guatemala)
Authors: Agrawal Laila S. , Pereira Mei-Ling , Mayer Ingrid A. , Gharzouzi Eduardo 
Published: May 2016

Abstract
Background: BC is the leading cause of cancer death in women in low- and middle-income countries (LMIC). For locally advanced BC, neoadjuvant treatment is often needed to downstage tumors prior to surgery, however many patients (pts) with BC in low-resource settings do not receive adequate therapy due to financial, social, and logistical barriers. This study evaluates the feasibility, adherence rates, and efficacy of neoadjuvant endocrine therapy with tamoxifen in a low-resource setting in Guatemala.
Methods: This is a single arm, single center study of neoadjuvant tamoxifen in pts with locally advanced HR+ BC. Pts were treated with tamoxifen for 4-6 weeks then underwent a core biopsy of their primary tumor for Ki67 evaluation. If Ki67 was ≤ 10%, tamoxifen was continued for a total of 4 months. If Ki67 &gt; 10%, pts were taken off study. The primary endpoint was assessing the proportion of pts who completed neoadjuvant treatment and received definitive surgery.
Results: The median age was 59 years (range 35-78). Nine (25.7%) pts were pre-menopausal and 26 (74.3%) pts were post-menopausal. Ductal histology was present in 31 (88.6%) pts and lobular histology in 3 (8.6%) pts. Clinical stage was IIB in 5 (14.3%) pts, IIIA in 22 (62.9%) pts, IIIB in 7 (20%) pts, and IIIC in 1 (2.9%) pt. All pts were estrogen receptor positive (ER+), 29 (82.9%) pts were progesterone receptor positive (PR+), and 2 (5.7%) pts were HER2+. Of the 35 pts enrolled, 32 (91.4%) returned for a biopsy after 4 weeks of tamoxifen. Seventeen pts were taken off study; 8 pts had Ki67 &gt; 10% and 9 pts had clinical progression. Fifteen (46.9%) pts continued on tamoxifen for 4 months. Of these, 13 pts (86.7%) underwent mastectomy. By exam, 6 pts had a complete response (CR) and 7 pts had a partial response. There was one pathologic CR. One pt was lost to follow-up and in one the tumor was still too large. The cost of neoadjuvant endocrine therapy with additional biopsy was 28% the cost of neoadjuvant chemotherapy in this setting.
Conclusions: Neoadjuvant tamoxifen is a tolerable, acceptable, and less expensive option for pts with HR+ locally advanced BC in a middle-income, low-resource setting, with good rates of adherence and clinical response. This has implications for other LMIC, but further studies are needed to better define patient selection, applicability, and length of treatment of neoadjuvant tamoxifen
Citation Format: Laila S. Agrawal, Mei-Ling Pereira, Ingrid A. Mayer, Eduardo Gharzouzi. Neoadjuvant endocrine therapy in locally advanced hormone receptor positive (HR+) breast cancer (BC) in a low-resource, middle-income setting (Guatemala). [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr C48.