CD133 is an independent predictive and prognostic marker in metastatic breast cancer.

Background: CD133 is a transmembrane glycoprotein and is considered the most common cell surface marker to identify cancer stem cells in hematological and solid tumors, including breast cancer.

Objectives: To evaluate the impact of immunohistochemical expression of CD133 on response rate and survival in metastatic breast cancer, as well as to correlate it with various demographics and clinicopathological characteristics.

Methods: One-hundred metastatic breast cancer patients were prospectively recruited at the Medical Oncology Department at South Egypt Cancer Institute during the period from January 2018 to January 2020.

Results: There was a statistically significant correlation between CD133 positive patients with various adverse clinicopathological parameters such as high grade (p= 0.013), higher tumor (p= 0.001), and nodal staging (p= 0.024) during a median follow-up time of 17 months. In addition, cases with CD133 positive expression had a significantly lower survival time than those with negative expression (3-years OS 37.4% versus 85.5%, p= 0.024). Regarding the response rate, CD133 positive patients had a lower response rate than negative patients (50% versus 54%, p= 0.012).

Conclusions: Positive CD133 is correlated with poor prognosis in metastatic breast cancer patients.