Real-World Survival Outcomes of Adjuvant Chemotherapy Versus Endocrine Therapy Alone in Hormone Receptor- Positive, Human Epidermal Growth Factor Receptor 2-Negative Invasive Lobular Carcinoma

Objective: This study aimed to compare disease-free survival (DFS) and overall survival (OS) between patients with hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative invasive lobular carcinoma (ILC) who received adjuvant chemotherapy plus endocrine therapy and those who received adjuvant endocrine therapy alone in a real-world setting.

Methods: In this single-center retrospective cohort study, patients diagnosed with stage I-III HR-positive, HER2-negative ILC who underwent curative surgery between January 2017 and June 2025 were included. Patients with metastatic disease, prior neoadjuvant therapy, or incomplete follow-up were excluded. Patients were categorized according to receipt of adjuvant chemotherapy. All patients received standard adjuvant endocrine therapy. The primary endpoints were DFS and OS.

Results: A total of 154 patients were included, with a median follow-up of 29.8 months. Patients who received adjuvant chemotherapy had higher-risk clinicopathological features, including more advanced tumor stage and nodal involvement. During follow-up, 6 recurrences (3.9%) were observed. Median DFS was 84.5 months in the endocrine therapy alone group and 95.5 months in the chemotherapy plus endocrine therapy group (log-rank P = .962). Median OS was not reached; the estimated mean OS was 96.4 months. Median OS was 85.6 months in the non-chemotherapy group and 95.8 months in the chemotherapy group (log-rank P = .785). In multivariable analysis, chemotherapy was not an independent predictor of DFS or OS.

Conclusion: In this real-world cohort of HR-positive, HER2-negative ILC, no statistically significant difference in DFS or OS was observed between treatment groups. These findings should be interpreted with caution given the limited number of events and baseline risk imbalance. The potential survival benefit of chemotherapy in this subtype may be limited and should be considered in individualized treatment decisions.

Cite this article as: Çokgezer S, Şenkal M, Safaraliyeva A, Topuz S, Saip PM, Ak N. Real-world survival outcomes of adjuvant chemotherapy versus endocrine therapy alone in hormone receptor-positive, HER2-negative invasive lobular carcinoma. Cerrahpaşa Med J 2026, 50, 0038, doi: 10.5152/cjm.2026.26038.