Aim: This study aimed to assess the molecular subtypes of breast cancer for patients attending a dedicated breast care center and examine the association with clinicopathological features, treatment and survival outcomes.
Methods: Demographic, clinicopathological and treatment details were collected from women with primary breast cancer. Immunohistochemical subtypes were also collected. The association between breast cancer subtypes and clinicopathological features was assessed using the chi-square or Fisher's exact test. Survival outcomes were compared among subtypes with the log-rank test.
Results: Immunohistochemical subtypes were not associated with tumor size, lymphovascular invasion or lymph node involvement but differed by histological grade (p=0.014) and nuclear grade of tumors (p=0.001). The 5-year overall survival estimates for luminal A, luminal B, HER-2-positive and triple-negative tumors were 100%, 96.2%, 71.4% and 92.3% respectively. Compared to luminal A tumors (93.4%), luminal B (80.8%), HER-2-positive (71.4%) and triple-negative (76.9%) tumors exhibited a reduced disease-free survival (DFS). Patients with ER-positive tumors had a higher DFS than their ER-negative counterparts (p=0.036). Patients with tumors expressing a low Ki-67 level had a more favorable prognosis (p=0.02).
Conclusions: The most prevalent luminal A subtype is associated with relatively better prognosis, whereas HER-2-positive and triple-negative tumors are prone to early relapse with diminished survival.