RESUMO
Background: Breast cancer is the most common cancer in Myanmar women. Revealing the hormonal receptor status, human epidermal growth factor receptor 2 (HER2) and Ki-67 expression is useful for estimating patient prognosis as well as determination of treatment strategy. However, immunohistochemical features and classification of molecular subtypes in breast cancers from Myanmar remain unknown. Methods: The clinicopathological features of 91 breast cancers from Myanmar women were examined. Immunohistochemistry was performed on tissue specimens with antibodies to estrogen receptor (ER), progesterone receptor (PgR), HER2, Ki-67, cytokeratin (CK)5/6 and CK14. Immunohistochemistry-based molecular subtyping was conducted. Results: Breast cancers in Myanmar women were relatively large, high grade with frequent metastatic lymph nodes. Of the 91 patients, tumors with ER positive, PgR positive, and HER2 positive were 57.1%, 37.4%, and 28.6%, respectively. The most prevalent subtype was luminal B (HER2-) (39.6%), followed by HER2 (22.0%), triple negative (TN)-basal-like (12.1%), luminal A (11.0%), TN-null (8.8%) and luminal B (HER2+) (6.6%). The mean Ki-67 expression of 91 cases was 33.9% (33.9% ± 19.2%) and the median was 28% (range; 4%-90%). The mean Ki-67 expression of luminal A, luminal B, HER2 and TN-basal-like/ null was 7%, 30%, 40%, and 57%/43%, respectively. A higher Ki-67 expression significantly correlated with a higher grade, larger size and higher stage of malignancy. Conclusions: We, for the first time, investigated the histopathological features of breast cancers from Myanmar women. Myanmar breast cancers appeared to be aggressive in nature, as evidenced by high frequency of poor-prognosis subtypes with high level of Ki-67 expression.
RESUMO
BACKGROUND: Human mammary tumor virus (HMTV) is 90-95% homologous to mouse mammary tumor virus (MMTV), one of the causal agents of murine mammary tumors. HMTV (MMTV-like) sequences were reported to be present in human breast cancers from several populations with a prevalence range of 0-78%; however, the prevalence of HMTV in breast cancers from Myanmar remains unknown. METHODS: Fifty-eight breast cancer samples from Myanmar women were examined in this study. DNA was isolated from formalin-fixed paraffin-embedded specimens, and HMTV envelope sequences were detected by semi-nested PCR. The sequence of the PCR products was also confirmed. RESULTS: Only 1.7% (1 of 58) of the breast cancers were positive for HMTV, and the sequence of PCR products was 98.9% identical to the reference HMTV sequence (GenBank accession No. AF243039). The tumor with HMTV was grade III invasive ductal carcinoma, 7.0 cm in size with lymph node metastasis (T3, N1, M0). CONCLUSIONS: We, for the first time, investigated the presence of HMTV in Myanmar breast cancer patients. In accordance with other Asian studies, the prevalence of HMTV in Myanmar was quite low, supporting the hypothesis that Asian breast cancers have different etiologies than in Western countries, where HMTV is more prevalent.
