Abstract 6399: SP in relation to NK1R and Ki67 predicts survival in hormone receptor negative breast cancer

Abstract

Background: Substance P (SP) is a tachykinin that has been implicated in carcinogenesis in several types of cancer through binding to neurokinin 1 receptor (NK1R). This study aimed to investigate the expression levels of SP and NK1R in hormone receptor negative (HR -ve) versus positive (HR +ve) breast cancer tissues and their relationship with clinicopathological characteristics of patients, Ki-67 index, and overall survival rate. Methods: Immunohistochemical expression levels of SP, NK1R and Ki-67 were measured in 144 paraffin-embedded breast cancer tissues (77 HR -ve and 67 HR +ve). SP and NK1R were scored semiquantitatively, while Ki-67 was obtained by the percentage of total number of tumor cells with nuclear staining. The optimal cutoff value for SP, NK1R and Ki-67 were assessed by Cutoff Finder. Pearson Chi-square (χ2) and Fisher’s exact tests were used to compare the staining scores between groups. ANOVA and student’s t-test were used to compare group means. Kaplan-Meier method with log-rank test was used for survival analysis. Results: High expression of SP, NK1R and Ki-67 was observed in 41%, 36.8% and 38.9% of cases, respectively. Association analyses revealed that SP expression in HR -ve breast cancer was higher in pN3 tumors (p=0.002), positive axillary lymph node metastasis (p=0.003), and high NK1R expression (p=0.010). In HR+ve breast cancer, SP was lower in HER2 positive tumors (p=0.001). Regarding NK1R, the association analysis showed that low NK1R expression level in HR +ve tumors was related to stage IV (p=0.023), pN1 (p=0.006), and low Ki-67 index (p=0.038). Survival analysis revealed that high SP level negatively impacted overall survival in HR-ve tumors that had low NK1R level (p=0.021). Moreover, high SP negatively impacted overall survival in HR-ve tumors that had low Ki-67 level (p=0.005). Nevertheless, NK1R expression did not impact survival in HR-ve or HR+ve cases despite stratification by SP and Ki-67 expression (p>0.05). Conclusion: Up to our knowledge, this is the first study to investigate the prognostic potential of SP and NK1R in breast cancer. Combined expression levels of SP and NK1R or Ki-67 could be used to predict survival in breast cancer patients with HR-ve tumors. Our findings suggest the potential role of SP and NK1R as therapeutic targets in breast cancer. Citation Format: Maha S. Al-Keilani, Rana Elstaty, Mohammad A. Alqudah. SP in relation to NK1R and Ki67 predicts survival in hormone receptor negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6399.