Clinical characteristics, tumor-infiltrating lymphocytes, and prognosis in HER2-low breast cancer: A comparison study with HER2-zero and HER2-positive disease.

HER2-low patients shared similar clinicopathological features with HER2-0 rather than HER2-positive cases and had relatively low sTILs. ER-negative/HER2-low patients had significantly inferior survival. sTILs increment was independently associated with favorable survival in the HER2-low group, suggesting a potential benefit from a novel treatment strategy.