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ABSTRACT: Background
Human epidermal growth factor receptor 2 (HER2)-positive tumors are defined by protein overexpression (3+) or gene amplification using immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH), respectively. HER2-positive tumors have historically included both IHC(3+) and IHC(2+, equivocal)/FISH(+) tumors and received the same treatment. Differences in biology between these two tumor types, however, are poorly understood. Considering anti-HER2 drugs bind directly to HER2 protein on the cell surface, we hypothesized anti-HER2 therapies would be less effective in IHC(2+)/FISH(+) tumors than in IHC(3+) tumors, leading to differences in patient outcomes.Methods
A total of 447 patients with HER2-positive invasive carcinoma who underwent curative surgery were retrospectively investigated. HER2 status was assessed in surgical specimens, except in patients who received neo-adjuvant chemotherapy, where biopsy specimens were employed.Results
Age, tumor size, lymph node status and ER status were independent factors relating to disease-free-survival, but no difference was observed between IHC(3+) and IHC(2+)/FISH(+) tumors. Kaplan-Meier analysis found patient outcomes did not differ, even after stratifying into those that did (n = 314), or did not (n = 129), receive chemotherapy with anti-HER2 drugs. In 134 patients who received NAC, pathological complete response rates in IHC(3+) and IHC(2+)/FISH(+) tumors were 45% and 21%, respectively. Survival after developing metastasis was significantly shorter in the IHC(2+)/FISH(+) group.Conclusions
The prognosis of patients with IHC(2+)/FISH(+) tumors did not differ from IHC(3+) tumors. However, the significance of HER2 protein overexpression in relation to treatment response remains unclear and warrants further investigations.
SUBMITTER: Horimoto Y
PROVIDER: S-EPMC8897871 | biostudies-literature | 2022 Mar
REPOSITORIES: biostudies-literature
Horimoto Yoshiya Y Ishizuka Yumiko Y Ueki Yuko Y Higuchi Toru T Arakawa Atsushi A Saito Mitsue M
BMC cancer 20220305 1
<h4>Background</h4>Human epidermal growth factor receptor 2 (HER2)-positive tumors are defined by protein overexpression (3+) or gene amplification using immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH), respectively. HER2-positive tumors have historically included both IHC(3+) and IHC(2+, equivocal)/FISH(+) tumors and received the same treatment. Differences in biology between these two tumor types, however, are poorly understood. Considering anti-HER2 drugs bind directly ...[more]