Comparison of programmed death-1 (PD-1)-positive T-cells with known prognostic indicators in breast cancer.

Background: Breast cancer is the most common cancer in women across the world. Immune cells can detect and destroy cancer cells. However, cancer cells acquire certain immune evasion mechanisms such as PD-1+ T-cells, to combat immune response. Limited number of studies have shown PD-1+ T-cells as a prognostic marker in breast cancer, but studies in India are far and few. Aims: To compare the positivity of PD-1-positive T-cells with known prognostic indicators in breast cancer. Materials and Methods: This descriptive, cross-sectional, prospo-retrospective study was conducted at the Department of Pathology of a Tertiary Care Hospital in Uttarakhand, India. A total of 50 cases were taken. Clinicopathological details were noted. On immunohistochemistry, PD-1 was membranous. The distribution pattern and percentage positivity of PD-1-positive T-cells were noted. Pearson Chi-square/Fisher's exact test was used. Results: The positivity of PD-1+ T-cells was found to be higher in tumors with luminal B subtype (P = 0.04). Out of the total CD3+ T-cells, 62% were found to be PD-1 positive. Conclusion: PD-1 positivity was associated with tumor molecular subtypes. No significant association of PD-1+ T-cells with other known prognostic markers of breast cancer was found.