Association between systemic immune-inflammation index and neoadjuvant chemotherapy efficacy as well as prognosis in...

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer with a relatively poor prognosis. Neoadjuvant chemotherapy (NAC) is the main treatment method. Due to the heterogeneity of the tumor, the chemotherapy response of TNBC patients is significantly different. Inflammation is closely related to the occurrence and development of cancer. The systemic immune-inflammation index (SII) is an indicator that can comprehensively reflect the state of systemic inflammation. This study aims to explore the association between SII and the NAC efficacy as well as the prognosis in TNBC.

The data of TNBC patients who underwent NAC and systemic treatment in Xiangya Hospital of Central South University from January 2015 to June 2019 were collected. According to the inclusion and exclusion criteria, 231 TNBC patients were finally included. The pre-NAC SII was calculated according to the blood routine results of the patients at 1 week before chemotherapy, and the patients were divided into a pre-NAC low SII group (SII<412, 115 cases) and a pre-NAC high SII group (SII≥412, 116 cases). The SII after chemotherapy was calculated according to the blood routine results of the patients at 2 to 3 months after the end of chemotherapy, and the patients were divided into a low SII group after chemotherapy (SII<474, 115 cases) and a high SII group after chemotherapy (SII≥474, 116 cases). Pearson's chi-square test was used to analyze the relationship between SII and other clinical characteristics of TNBC patients, and the relationship between the NAC efficacy and clinical characteristics of TNBC patients. Binary logistic regression analysis was used to find independent factors that affect the efficacy of NAC in TNBC patients. Kaplan-Meier curve analysis was used to analyze factors affecting the prognosis of TNBC patients. Cox regression model was used to find independent factors affecting the prognosis of TNBC patients.

Before NAC, the differences in SII between groups with different ages and tumor sizes were significant (P=0.007 and P=0.002, respectively); after chemotherapy, there were no significant differences in SII between different ages, tumor sizes, histological grades, lymph node staging, and Ki-67 groups (all P>0.05). There were 115 patients with low SII before NAC, with a pathological complete response (pCR) rate of 15.7%; there were 116 patients with high SII before NAC, with a pCR rate of 6.0%. Patients with low SII before NAC had a higher pCR rate than patients with high SII before NAC, and the difference was statistically significant (P=0.019).There were 156 patients with lymph node staging pN₀, with a pCR rate of 14.7%; and there were 75 patients with lymph node staging pN₁-pN₂, with a pCR rate of 2.7%. Patients with lymph node staging pN₀ had a higher pCR rate than those with lymph node staging pN₁-pN₂, and the difference was significant (P=0.006). During the follow-up, 34 patients had local recurrence or distant metastasis. The Kaplan-Meier survival curve showed that the 3-year disease-free survival (DFS) rates for patients with low SII before NAC and high SII before NAC were 87.8% and 82.8%, respectively, and the former was significantly higher than the latter (P=0.005); the 3-year DFS rates for patients with tumor sizes of T₁-T₂ and T₃ were 89.0% and 67.5%, respectively, and the former was significantly higher than the latter (P=0.001); the 3-year DFS rates for patients with lymph node staging of pN₀ and pN₁-pN₂ were 87.8% and 82.8%, respectively, and the former was significantly higher than the latter (P=0.009). Cox analysis showed that SII before NAC and tumor size were independent influencing factors of patients' DFS (P=0.038, P=0.010, respectively).

SII has important clinical significance in predicting the efficacy and prognosis of NAC in TNBC patients, and it has the potential to be a biomarker.