Ki-67 as a predictor of pathologic complete response in triple-negative breast cancer: a retrospective study

Volume: 8 Issue: 1, 42 - 48, 06.01.2026

Neslihan Özyurt , Aykut Turhan

Abstract

Aims: This retrospective observational study investigated the relationship between the Ki-67 proliferation index and pathologic complete response (pCR) in 113 women with triple-negative breast cancer (TNBC) who underwent platinum-based neoadjuvant chemotherapy. The study also evaluated the prognostic value of Ki-67 expression levels for overall survival (OS) and disease-free survival (DFS) rates.
Methods: This retrospective analysis was conducted on a single-center cohort of 113 patients diagnosed with TNBC who underwent platinum-based neoadjuvant chemotherapy. Receiver operating characteristic (ROC) curve analysis and multivariate binary logistic regression were performed to assess the predictive value of Ki-67 for pCR. Survival outcomes were evaluated using the Kaplan–Meier method and compared using the log-rank test.
Results: ROC analysis identified an optimal Ki-67 cutoff value of 52.5% for distinguishing patients who achieved pCR from those who did not. Patients with Ki-67 values ≥52.5% were more likely to achieve pCR than those with lower values (AUC=0.625, indicating modest discriminative ability, p=0.016). In multivariate logistic regression, high Ki-67 expression (≥52.5%) was a significant independent predictor of pCR (OR = 3.13, 95% CI: 1.32–7.40, p=0.01). However, Ki-67 expression levels were not significantly correlated with OS or DFS. Patients who achieved pCR had notably longer DFS than those who did not (log-rank χ²=11.128, p<0.001); however, there was no significant difference in OS between the two groups.
Conclusion: The study suggests that The Ki-67 index is an independent predictor of pCR in platinum-based neoadjuvant therapy for TNBC, although our findings did not show a significant link with survival outcomes. Ki-67 is a routinely accessible marker that aids in predicting treatment response in clinical settings.

Keywords

Ki-67 antigen , triple negative breast neoplasms , neoadjuvant therapy , platinum compounds , pathologic complete response

Ethical Statement

The study was conducted in accordance with the Declaration of Helsinki and approved by the Non-Interventional Clinical Research Ethics Committee of Ordu University (Approval No: 358, Date: October 31, 2025). This study was conducted at the Department of Medical Oncology, Ordu University Training and Research Hospital.

Supporting Institution

The authors declare that this study received no financial support.

Thanks

The authors thank the staff of the Oncology Department of Ordu University Training and Research Hospital for their assistance with data collection and the professional biostatistician for conducting the statistical analyses. During the preparation of this manuscript, the authors used Paperpal (by Editage) and ChatGPT (OpenAI GPT-5, 2025 release) for grammar corrections, paraphrasing, and translation. The authors reviewed and edited all the outputs and took full responsibility for the content of this publication.

Triple negatif meme kanserinde patolojik tam yanıtın tahmin edicisi olarak Ki-67: retrospektif bir çalışma

Abstract

Amaç: Bu retrospektif gözlemsel çalışma, platin bazlı neoadjuvan kemoterapi uygulanan 113 üçlü negatif meme kanserli (TNBC) kadında Ki-67 proliferasyon indeksinin patolojik tam yanıt (pCR) ile ilişkisini araştırmıştır. Ayrıca Ki-67 ekspresyon düzeylerinin genel sağkalım (OS) ve hastalıksız sağkalım (DFS) üzerindeki prognostik değerleri de değerlendirilmiştir.

Yöntem: Ki-67 indeksinin pCR’yi öngörmedeki değerini değerlendirmek için alıcı işletim karakteristiği (ROC) eğrisi analizi ve çok değişkenli ikili lojistik regresyon analizi uygulanmıştır. OS ve DFS dahil sağkalım sonuçları Kaplan–Meier yöntemi ile analiz edilmiş, gruplar arası farklar log-rank testi ile karşılaştırılmıştır.

Bulgular: ROC analizi, pCR’yi öngörmede optimal Ki-67 kesim değerini %52.5 olarak belirlemiştir. Ki-67 düzeyi ≥%52.5 olan hastalar, daha düşük değerlere sahip olanlara kıyasla anlamlı olarak daha yüksek pCR oranına ulaşmıştır (AUC = 0.625, p = 0.016). Çok değişkenli lojistik regresyon analizinde yüksek Ki-67 ekspresyonu pCR’nin bağımsız bir belirleyicisi olarak saptanmıştır (odds oranı = 2.89, %95 GA: 1.11–7.56, p = 0.029). Ancak Ki-67 ekspresyonu OS veya DFS ile anlamlı bir ilişki göstermemiştir. pCR elde eden hastalarda, pCR elde etmeyenlere göre DFS anlamlı derecede daha uzun bulunmuştur (log-rank χ² = 11.128, p < 0.001).

Sonuç: Ki-67 indeksi, TNBC hastalarında platin bazlı neoadjuvan tedaviye yanıtın bağımsız bir öngördürücüsüdür; ancak sağkalım açısından prognostik bir belirteç değildir. Uzun dönem prognozdan ziyade tedavi yanıtını öngörmede pratik ve maliyet etkin bir biyobelirteç olarak kullanılabilir.

Keywords

Ki-67 Antijeni , Triple Negatif Meme Neoplazmları , Neoadjuvan Tedavi , Platin Bileşikleri , Patolojik Tam Yanıt

Ethical Statement

Çalışma Helsinki Bildirgesi'ne uygun olarak yürütülmüş ve Ordu Üniversitesi Girişimsel Olmayan Klinik Araştırmalar Etik Kurulu tarafından onaylanmıştır (Onay No: 358, Tarih: 31 Ekim 2025). Bu çalışma Ordu Üniversitesi Eğitim ve Araştırma Hastanesi Tıbbi Onkoloji Anabilim Dalı'nda gerçekleştirilmiştir.

Supporting Institution

Yazarlar bu çalışmanın finansal destek almadığını beyan etmektedirler.

Thanks

Yazarlar, veri toplama sürecindeki yardımları için Ordu Üniversitesi Eğitim ve Araştırma Hastanesi Onkoloji Anabilim Dalı çalışanlarına ve istatistiksel analizleri gerçekleştiren profesyonel biyoistatistik uzmanına teşekkürlerini sunarlar. Bu makalenin hazırlanması sırasında yazarlar, dil bilgisi düzeltmeleri, paraflama ve çeviri için Paperpal (Editage tarafından) ve ChatGPT (OpenAI GPT-5, 2025 sürümü) kullanmışlardır. Yazarlar, tüm çıktıları inceleyip düzenlemiş ve bu yayının içeriğinin tüm sorumluluğunu üstlenmişlerdir.

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