The systemic inflammation response index (SIRI) predicts oncological outcome and correlates with tumor burden in metastatic pancreatic cancer.

Abstract

e15537 Background: The SIRI, defined by neutrophil x monocyte/lymphocyte 109/L, has recently emerged as a prognostic factor for pancreatic cancer. However, the association between SIRI values after chemotherapy and tumor response has not been evaluated. Methods: 161 metastatic pancreatic cancer patients were retrospectively analyzed. Associations between overall survival (OS), chemotherapy and SIRI were analyzed. A larger number of patients with pre-treatment SIRI (pre-SIRI) were collected so, post-treatment SIRI (post-SIRI) evaluated after three cycles of chemotherapy, was adjusted for analysis. Results: Median age 66 years. 59 (36%) received gemcitabine + nab-paclitaxel, 40 (24%) gemcitabine, 22 (17%) mFOLFIRINOX, 13 (7%) other regimens. 27 (16%) had not received treatment. Pre-SIRI≥2.3×109/L was an independent, negative predictor of OS compared to pre-SIRI < 2.3×109/L [5 versus 16 months, Hazard Ratio (HR) 2.87, Confidence Interval (CI) 95% 2.02-4.07, P< 0.0001]. In the whole cohort, we observed SIRI values increased after treatment (median pre-SIRI: 1.6×109/L; post-SIRI: 2.3×109/L; P= 0.007). Thus, we analyzed the association between tumor response measured by RECIST and pre-SIRI and post- SIRI values. Patients with progressive disease (PD) showed a higher pre-SIRI than those who had a response to chemotherapy (2.7×109/L versus 1.2×109/L, respectively; P< 0.001). We also observed a statistically significant increase in post-SIRI values for PD compared to tumor response (3.2×109/L versus 1.7×109/L, respectively; P= 0.012). As observed for pre-SIRI, post-SIRI ≥2.3×109/L showed a shorter OS compared to post-SIRI < 2.3×109/L (8 versus 17 months, respectively; P= 0.016). Furthermore, patients with pre-SIRI ≥2.3×109/L were more likely to benefit from mFOLFIRINOX showing a median OS of 17 months compared to 6 and 4 months for gemcitabine + nab-paclitaxel and gemcitabine, respectively ( P< 0.001). Conversely, there was no difference for pre-SIRI < 2.3×109/L: 15.9 months versus 16.5 and 16, respectively. Conclusions: SIRI≥2.3×109/L was a prognostic factor for metastatic pancreatic cancer. An elevated post-SIRI showed an association with disease progression and a negative impact on survival. Therefore, an increase in SIRI could be related to high tumor burden and be useful to appropriately select patients who would benefit of a more intensive first-line chemotherapy regimen.