Assessment of Pathological Features and Molecular Profiling of Triple-Negative Breast Cancer: A Retrospective Study at King Abdulaziz University Hospital, Jeddah, Saudi Arabia

Background: Triple-negative breast cancer (TNBC) is a hostile sub-type consisting of nearly 10-20 % of breast cancer patients. TNBC has been known to have a poor prognosis and overall survival (OS) compared to many other breast cancer tumors categories. These tumors are highly aggressive and have a higher risk of early recurrence. Nevertheless, no evidence exists to date and this is also the situation in Saudi Arabia. Recently, it was found to be a heterogeneous disease.

Objective: To subtype breast cancer (BC) following the recent advance molecular classification, and to ascertain the correlation of those sub-types with pathological parameters and to study triple-negative breast cancer and its correlation with other subtypes and its association with recurrence and poor prognosis.

Methods: The study was performed on 740 breast cancer patients at the Department of Pathology, King Abdulaziz University Hospital (KAUH), Jeddah, Kingdom of Saudi Arabia diagnosed between 2005 to 2018. The parameters like Estrogen receptor (ER), Progesterone receptor (PR), and human epidermal growth factor receptor immunostaining were analyzed semi-quantitatively to establish the HER-2, triple-negative, molecular subtypes of luminal A and B in paraffin-embedded sections of BC. We review the histopathology report, tumor invasion, grade, margin, type of surgery, recurrence, metastases, and survival rate.

Results: The most common sub-types were luminal B (19.7%), followed by triple-negative breast cancer (10.9%) and HER2-positive (9.5%), whereas luminal A was the least common subtype (8.1 %). In luminal A majority of their age less than or equal to 50 years, most of these subtypes have tumor invasion, 59.2% of triple-negative breast cancer had positive axillary lymph node involvement. 63.4 % of triple-negative breast cancer had grade 3 tumors most of the recurrence in luminal B.

Conclusion: The biological behaviors of each molecular subtype is likely to be with characteristic pathological features. In addition to molecular sub-typing and further prognostic indicators, might be useful in investigating the prognosis and management of BC patients. The early diagnosis and screening of BC are recommended in our population.