IL2 and digestive system neoplasm: Subgroup analyses were carried out according to tumor sites (gastrointestinal tumor, hepatobiliary and pancreatic tumor, neurologic tumor, and other tumors), lymphodepletion before T cell infusion (yes or no), transfection method (by lentivirus or retrovirus), cell culture duration (<14 days vs. ≥14 days), persistence of CAR-T cells (<4 weeks vs. ≥4 weeks), transfection efficacy (<50% vs. ≥50%), total cell dose (<109 vs. ≥109), and administration of IL-2 (yes or no).