Association of tumor volume with molecular phenotypes in breast cancer: A study at a tertiary care hospital

Breast cancer is a common cause of mortality among women worldwide. The incidence of this disease is higher in developing countries than in Western countries. Variations are noted in the distribution of breast cancer subtypes between Eastern and Western populations. Breast cancer is a heterogeneous lesion at the molecular level, and its prognosis is dependent on multiple factors. The present study aimed to determine the distribution of various molecular phenotypes of breast cancer and its association with tumor volume in patients presenting to a tertiary care hospital. The present observational cross‑sectional study was conducted at a tertiary care medical college hospital. Following analysis using immunohistochemistry for estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 (HER2), and Ki67, all patients with breast cancer were classified into the luminal A, luminal B, HER2‑enriched and triple‑negative breast cancer (TNBC) groups. In addition, the age and tumor volume of the patients were compared among the different subtypes of breast cancer. Of the 165 patients with infiltrating ductal carcinoma (type not otherwise specified), the most common molecular phenotype was TNBC (39.4%), followed by luminal B (24.2%). The HER2‑enriched and luminal A subtypes constituted 20.6 and 15.8%, respectively. There was no significant difference in the average age of the patients among the different molecular phenotypes. The smallest median tumor volume was observed in the luminal A (4.5 cm³) group, followed by the HER2‑enriched (8.0 cm³), TNBC (24.0 cm³) and luminal B (29.94 cm³) groups. TNBC was the most common molecular phenotype. The tumor volume was the smallest in the patients with the luminal A subtype. As tumor volume has prognostic value, the poor prognosis of patients with TNBC and HER2‑enriched breast cancer may be improved via targeted therapy. It is hoped that the findings of the present study may prove useful in the management of patients with breast cancer.