Clinicopathological characteristics and long-term prognosis of triple-negative breast cancer patients with HER2-Low expression: a retrospective propensity score-matched cohort study

The objective of the current research was to assess the clinicopathological characteristics and long-term prognosis of triple-negative breast cancer (TNBC) patients with human epidermal growth factor receptor 2 (HER2)-low status following breast surgery.

A total of 202 TNBC patients treated at Qingdao Central Hospital from January 2010 to December 2019 were included, comprising 71 HER2-low and 131 HER2-zero patients. Propensity score matching (PSM) was applied to minimize differences between the cohorts.

HER2-low TNBC patients had lower histological grade, lower Ki-67 expression levels, and a higher prevalence of hypertension compared to HER2-zero TNBC patients. Before and after PSM, the HER2-low group consistently exhibited a lower recurrence rate and longer RFS compared to HER2-zero TNBC patients. HER2-low status was validated as an independent low-risk factor for RFS both pre-PSM (HR 0.354, 95% CI 0.178–0.706, p = 0.003) and post-PSM (HR 0.405, 95% CI 0.185–0.886, p = 0.024). No statistically significant differences in mortality rate and OS were observed, both before and after PSM.

HER2-low and HER2-zero TNBC patients show significant clinicopathological differences. Compared to HER2-zero, HER2-low status is linked to better long-term prognosis and serves as an independent low-risk factor for RFS in TNBC patients.