Subtypes of Breast Cancer in Lao P.D.R.: A Study in a Limited-Resource Setting

Abstract

Aim: The purpose of this study is to evaluate the prevalence of the immunohistochemical subtypes of breast cancer<br />among Lao women by using immunohistochemistry (according to the St. Gallen 2017 guidelines) and to study their<br />correlation to clinicopathological features in order to help guide better treatment plans for patients. Materials and<br />methods: Formalin-fixed and paraffin embedded tissue blocks of 76 cases of primary invasive breast cancer were<br />retrieved from the University of Health Sciences, Vientiane, Lao PDR, from 2013 to 2016. Patients' information and<br />previous histological reports were reviewed. Immunohistochemistry was done using antibodies against estrogen receptor<br />(ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2/neu) and Ki-67 (MIB-1). Results:<br />The mean age of the patients was 49 years, and the major histologic type was invasive ductal carcinoma, NOS (90.7%).<br />The proportion of each subtype was hormone receptor-positive and HER2-negative, 44.7%; hormone receptor-positive<br />and HER2-positive, 3.9%; hormone receptor-negative and HER2-positive, 13.2%; and triple-negative, 38.2%. ER was<br />positive in 40.8% of the cases, while PR was positive in 47.4%. More than half of the cases were poorly differentiated<br />cancer (65.8%), followed by moderately differentiated (34.2%). Tumors presented with pT2 (60.5%), followed by pT3<br />(25.0%) and pT4 (7.9%). Conclusion: Breast cancer among Lao women is characterized by a large percentage of the<br />triple-negative subtype that is less susceptible to hormonal treatments. The empirical treatment with tamoxifen should<br />be reconsidered since it would be less effective to these patients. More importantly, basic pathology services should<br />be the first requirement in Lao PDR in order to provide adequate care.