HER2-Low Expression Predicts Improved Pathologic Response but not Disease-Free Survival in HR-Positive/HER2-Negative Breast Cancer Patients Receiving Neoadjuvant Chemotherapy

Authors : Ahmet Bilgehan Şahin, Cagla Karaoglu, Mursel Sali, Buket Erkan Ozmarasali, Ender Eren Özçelik, Yagmur Karaman, Gul Akın, Hulya Odabası Bukun, Ali Aktas, Mine Özşen, Birol Ocak, Adem Deligönül, Erdem Çubukçu, Türkkan Evrensel

Pages : 569-575

Doi:10.32708/uutfd.1813271

View : 103 | Download : 276

Publication Date : 2025-12-08

Article Type : Research Paper

Abstract :This retrospective single-center study aims to evaluate the predictive and prognostic significance of HER2-low (IHC 1+/2+ ISH–) compared with HER2-0 status in hormone receptor (HR)-positive / HER2-negative breast cancer patients treated with neoadjuvant chemotherapy (NACT). A cohort of 404 HR-positive / HER2-negative breast cancer patients treated with NACT between January 2008 and December 2019 at Bursa Uludag University was analyzed. Clinicopathologic variables, pathologic complete response (pCR), and long-term survival were assessed. Logistic regression identified independent predictors of pCR, and Cox proportional hazards modelling was used for disease-free survival (DFS). Of 404 patients, 117 (29.0%) were HER2-low and 287 (71.0%) were HER2-0. The pCR rate was significantly higher in the HER2-low group than in the HER2-0 group (9.4% vs 4.2%; p = 0.040). Multivariable logistic regression analysis revealed that HER2-low status (OR=2.88; 95% CI, 1.17–7.12; p=0.022) and a higher Ki-67 index (OR =1.03 per 1% increase; 95% CI, 1.01–1.05; p=0.003) were independent predictors of pathological complete response (pCR). The median follow-up time was 110.2 months (range, 10.5–248.9 months). The 5- and 10-year DFS rates were 85.1% and 73.7%, respectively; OS rates were 86.4% and 75.3%. In multivariable Cox regression, only pathological stage remained an independent predictor of DFS (HR=2.02; 95% CI 1.55–2.61; p<0.001), while HER2 status was not significant (HR=0.97; 95% CI 0.66–1.43; p=0.861). In conclusion, HER2-low status was associated with improved pCR but not with long-term survival. Pathologic stage remained the strongest determinant of DFS, and HER2-low appears to represent a biologic continuum within HER2-negative disease rather than a distinct prognostic subtype.
Keywords : HER2-düşük meme kanseri, hormon reseptör pozitif meme kanseri, neoadjuvan kemoterapi, patolojik tam yanıt, hastalıksız sağkalım

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