Effect of HER2-low expression on neoadjuvant efficacy in operable breast cancer

• Xiaoli Yi ^[2] ; Shasha Hu ^[1] ; Meili Ma ^[2] ; Dongshuai Huang ^[2] ; Yan Zhang ^[2]
  1. [1] Affiliated Hospital of Qingdao University

     Affiliated Hospital of Qingdao University

     China

     
  2. [2] Qingdao Hospital, University of Health and Rehabilitation Sciences (Qingdao Municipal Hospital), Qingdao, China
• Localización: Clinical & translational oncology, ISSN 1699-048X, Vol. 26, Nº. 4, 2024, págs. 880-890
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • Objective To investigate the effects of HER2-low expression (HER2-low) and HER2-zero expression (HER2-0) on the pathological complete response (pCR) rate and survival of patients following neoadjuvant chemotherapy.

    Methods Eighty-six patients were followed up. Patients were divided into HER2-0 (immunohistochemistry (IHC) score of 0 (IHC0)) and HER2-low (IHC1+ or IHC2+/in situ hybridization non-amplified (ISH-)) groups according to the IHC detection of puncture tissues. After neoadjuvant chemotherapy, the clinical characteristics, pCR rate and DFS were compared between the two groups.

    Results There were 24 (27.9%) cases with HER2-0 and 62 (72.1%) cases with HER2-low. Hormone receptor-positive (HR+) patients accounted for 77.4% of the HER2-low group, which was higher than 70.8% in the HER2-0 group, and there was no significant difference between the two groups (p = 0.524). There were statistical differences in the pT and pN stages between HER2-low and HER2-0 subgroups in the triple-negative breast cancer (TNBC) group after neoadjuvant chemotherapy. The HER2-low subgroup had an earlier T stage (p = 0.009), and the ratio of N0 to N1 in the HER2-low and HER2-0 subgroups was 92.9% and 71.4%, respectively (p = 0.037). The Ki-67 index and median PR value were significantly lower in the HER2-low group after neoadjuvant chemotherapy (p = 0.002, p = 0.018). The HER2 IHC score was altered in the HER2-low group, and the HER-2 (2+) score changed significantly (p = 0.002). Seventy-eight patients with complete immunohistochemical data were analyzed. The discordance rate of the IHC score of HER2 after neoadjuvant chemotherapy was 38.5%, and eight patients with HER2-low showed HER2-0 status, with a discordance rate of 10.3%. After neoadjuvant chemotherapy, The pCR rate was significantly lower in the HER2-low group compared with that in the HER2-0 group (4.8% vs. 8.3%; p = 0.914), but the recurrence and metastasis rates were lower in the HER2-low group (9.7% vs. 20.8%; p = 0.165). There were no differences in DFS between the two groups at 6, 12, 24, and 36 months (p = 0.076; p = 0.518; p = 0.245; p = 0.406). The subgroup analysis demonstrated no significant difference in DFS between HER2-low and HER2-0 subgroups in the HR + and TNBC groups (p = 0.141, p = 0.637).

    Conclusion This retrospective study indicates that HER2-low has no significant effect on neoadjuvant efficacy in operable breast cancer. There were no statistical differences in clinical characteristics, pCR rate, and DFS between the HER2-low and the HER2-0 groups. There was no evidence that a HER2-low status constitutes a unique biological subtype, suggesting that more clinical data might be needed to verify these observations.