Serum IL-33 level is a predictor of progression-free survival after chemotherapy.

This study aimed to evaluate the association between of serum IL-33 (sIL-33) level in gastric cancer (GC) patients and progression-free survival (PFS). A total of 62 patients with advanced GC and 32 healthy subjects were enrolled. sIL-33 level was detected in pre-chemotherapy patients, post-chemotherapy patients and healthy subjects, respectively. sIL-33 levels were 131.9 (95% CI 105.9-184.9) pg/mL, 95.1 (95% CI 70.8-140.2) pg/mL and 95.7 (95% CI 73.3-114.3) pg/mL in pre-chemotherapy patients, post-chemotherapy patients and controls, respectively. The sIL-33 level in pre-chemotherapy patients was significantly higher than that in both post-chemotherapy patients and controls (P < 0.001 and P < 0.001, respectively). There was no statistically significant difference between the sIL-33 levels in post-chemotherapy patients and controls (P > 0.05). PFS in patients with the decline extent > 30.1% (median PFS not reached) was statistically significant longer than that (median PFS 7 months, 95% CI 1.569 - 12.431) in patients with the decline extent ≤ 30.1% (P = 0.003). The decline extent of sIL-33 level (> 30.1%) was associated with longer PFS (P = 0.006). Distant metastasis was associated with the decline extent of sIL-33 level (P = 0.034). The decline extent of sIL-33 after chemoresistance could be regarded as a predictor of the PFS of GC patients.