Relationship between the ultrasound features of different molecular subtypes of breast cancer and positive PD-1/PD-L1 expression

Objectives To analyze differences in programmed cell death protein 1/ligand 1 (PD-1/PD-L1) expression, as well as the relationships between ultrasound/contrast-enhanced ultrasound characteristics and PD-1/PD-L1 expression, among invasive breast cancer molecular subtypes.Methods The study included 172 invasive breast cancer patients with surgical resection and pathological confirmation at the First Affiliated Hospital of Xinjiang Medical University from June 2016 to April 2022. PD-1/PD-L1 expression was detected by immunohistochemistry. All patients underwent conventional ultrasound and some underwent contrast-enhanced ultrasound examination before resection.Results PD-1 and PD-L1 were expressed in 112 and 121 cases, respectively. The luminal B and HER-2 subtypes had the lowest and highest PD-1 expression rates, respectively. The luminal B and triple-negative subtypes had the lowest and highest PD-L1 expression rates, respectively. Among 112 PD-1-positive cases, most luminal B cases exhibited ill-defined margins, while distant metastasis was more common in triple-negative cases. Among 121 PD-L1-positive cases, many HER-2-positive and triple-negative cases presented as large masses (diameter >= 2 cm), while luminal B cases were more likely to show calcification. Most luminal B PD-L1-positive cases displayed indistinct margins on contrast-enhanced ultrasound.Conclusions PD-1 expression differed among molecular subtypes of invasive breast cancer. Ultrasound/contrast-enhanced ultrasound features correlated with PD-1/PD-L1 expression in different breast cancer subtypes.