Evaluation of breast cancer metastasis and mortality rates based on molecular subtype: A description study

BACKGROUND: Breast cancer in Indonesia has continued to increase. One diagnostic modality is immunohistochemical examination to determine breast cancer subtypes. OBJECTIVE: To determine breast cancer metastasis and mortality rates based on molecular subtypes. METHODS: A descriptive study was conducted based on retrospective data from hospital medical records from January 2016 to December 2019. The data comprised age, clinical stage, histopathological grade, molecular subtype, location, metastasis, and breast cancer mortality. The data were processed and analyzed. RESULTS: This study involved 172 patients. The most prevalent breast cancer subtypes were luminal A (60, 34.8%), followed by HER2 (47, 27.4%), triple-negative (38, 22.4%), and luminal B (27, 15.4%). The metastasis rate was 37.21% (64/172), with bone the tissue most affected (32 cases, 50%), followed by lung (24 cases, 37.5%) and liver (8 cases, 12.5%). The highest rates of bone, lung, and liver metastases were subtypes luminal A (31%), HER2 (29%), and triple-negative (38%), respectively. The mortality rate was 21% (36/172), with most in the triple-negative group (28.9%), followed by luminal B (25.9%), HER2 (21.2%), and luminal A (13.3%). CONCLUSIONS: Determination of breast cancer molecular subtypes through immunohistochemistry can determine the level of metastasis and mortality in breast cancer.