Background: The immune system has been shown to play an important role in gastrointestinal stromal tumor (GIST). The neutrophil-to-lymphocyte ratio (NLR) in blood is an easily assessable parameter of systemic inflammatory response. The aim of this study was to determine whether the NLR is prognostic in GIST.
Methods: A total of 339 previously untreated patients with primary, localized GIST operated at our institution between 1995 and 2010 were identified from a prospectively collected sarcoma database. NLR was assessed preoperatively. Patients who received adjuvant imatinib treatment were excluded from the analysis (n = 64). Cox regression models were calculated and correlation analyses were performed.
Results: On univariate analysis, NLR was associated with recurrence-free survival (RFS) (P = 0.003, hazard ratio 3.3, 95 % confidence interval 1.5-7.4). Patients with a low NLR had a 1- and 5-year RFS of 98 and 91 %, compared with 89 and 76 % in those with a high NLR. The median RFS was not reached. Positive correlations were found between NLR and mitotic rate (Pearson correlation coefficient [r] = 0.15, P = 0.03), and NLR and tumor size (r = 0.36, P = 0.0001). RFS in patients with a GIST >5 cm with low NLR was significantly longer compared to patients with high NLR (P = 0.002). Flow cytometry analysis of freshly obtained GISTs revealed that neutrophils constituted a minimal percentage of intratumoral immune cells.
Conclusions: NLR is a surrogate for high-risk tumor features. Elevated blood NLR appears to represent systemic inflammation in patients with high-risk GIST.