A systemic inflammation response index (SIRI) correlates with survival and predicts oncological outcome for mFOLFIRINOX therapy in metastatic pancreatic cancer.

Objectives: Systemic inflammatory response and survival has not been evaluated as a predictive factor of chemotherapy in metastatic pancreatic cancer. The aim of this study was to evaluate the prognostic and predictive value of a baseline Systemic Inflammation Response Index (SIRI) in metastatic pancreatic cancer.

Methods: Retrospective study of 164 metastatic pancreatic cancer patients. Associations between overall survival (OS), progression free survival (PFS), chemotherapy and SIRI were analyzed. SIRI is defined by neutrophil x monocyte/lymphocyte 10/L.

Results: Median age 66 years. 22 (13%) received mFOLFIRINOX, 59 (36%) gemcitabine + nab-paclitaxel, 40 (24%) gemcitabine, 13 (8%) other regimens and 30 (18%) had not received treatment. Patients with SIRI<2.3 × 10/L showed a statistically significant improvement in OS compared to SIRI≥2.3 × 10/L [16 months versus 4.8 months, Hazard Ratio (HR) 2.87, Confidence Interval (CI) 95% 2.02-4.07, p < 0.0001] that was confirmed in multivariate analysis. In addition, patients with SIRI<2.3 × 10 showed a longer PFS (12 versus 6 months, HR 1.92, IC 95% 1.314-2.800, P = 0.001). Furthermore, we observed that patients with SIRI ≥2.3 × 10/L were more likely to benefit from mFOLFIRINOX therapy. Patients with an elevated SIRI treated with mFOLFIRINOX versus gemcitabine plus nab-paclitaxel and gemcitabine showed a clinically and statistically significant difference in median OS of 17 months compared to 6 and 4 months respectively (p < 0.001). Conversely, the difference was not clinically significant in the SIRI<2.3 × 10/L subgroup: 15.9 months versus 16.5 and 16, respectively.

Conclusion: An elevated SIRI (≥2.3 × 10/L) was an independent prognostic factor for patients with metastatic pancreatic cancer, warranting prospective evaluation.