Metastatic breast cancer (MBC) had a different prognosis based on their subtype. Although it varied theoretically, the cancer registry and studies of this topic are still limited especially in our country. This study aims to analyze MBC profile and investigate the significance of overall survival (OS) according to tumor subtype.
We evaluated MBC patients between 2016-2018 with known histopathology report, hormone receptor (HR), human epidermal growth factor receptor 2 (HER2), and metastatic pattern reported from hospital registered medical records, the characteristics including age and BMI were collected and analyzed. Patients divided into 5 groups, hormonal (HR+/HER2-), HER2-only (HR-/HER2+), luminal (ER or PR+, HER2+)), triple-positive (ER+/PR+/HER2+), and triple-negative (HR-/HER2-). Kaplan-Meier method with log-rank test and life time table were used to investigate the survival.
We included 119 MBC patients, the median follow-up was 22 months. All the patients were female, the highest population in 30 to 50 years old group (53%), overweight and obese BMI group (56.3%), ductal carcinoma (84%), and hormonal subtype (49.6%). Most of the patients had visceral metastasis (79%) and treated with combined cancer therapy (73%). HER2-only patients had a lower mean (13.7 vs 30.4 months) and median (16 vs 24 months) survival compared to hormonal subtype, the survival comparison of both groups is significant (P = 0.10). OS at 3 years for HER2-only was 33.3% and 70% for hormonal type. There is no significant survival comparison between other groups.
There were substantial differences in survival between HER2-only and hormonal subtype. HER2-only patients had worse mean, median, and OS compared to hormonal. This result could support the possibility of MBC with hormonal expression had better survival.