Transarterial Chemoembolization and Chemo‐Immunoembolization in Locally Advanced Rectal Cancer: An Updated Systematic Review

Locally advanced rectal cancer (LARC) often requires aggressive multimodal therapy, yet pathological complete response (pCR) to standard chemoradiotherapy remains low. Transarterial chemoembolization (TACE) enables targeted locoregional delivery of chemotherapy to tumor-feeding arteries, and its recent extension, chemo-immunoembolization, permits intraarterial delivery of immune checkpoint inhibitors. This updated systematic review searched MEDLINE, EMBASE, and Web of Science from inception to June 2026 for studies of TACE or transcatheter rectal arterial chemoembolization (TRACE) in LARC, with quality appraised using the Newcastle-Ottawa Scale. Nine studies encompassing 822 patients, 582 of whom received TACE or TRACE, were included, predominantly from China; one further trial is ongoing. pCR rates ranged from 10% to 44.74%. In comparative studies, TRACE with oxaliplatin was associated with lower tumor regression grade 3 (TRG3) rates, reaching significance in the largest comparison, and with a survival benefit in an exploratory TRG3 subgroup analysis, suggesting a possible role in chemoradiotherapy-resistant disease. The highest pCR occurred in a phase II trial of intra-arterial tislelizumab plus TACE in mismatch repair-proficient LARC, with no grade 3-4 immune-related adverse events. Major complications were uncommon. TACE may improve pathological response with an acceptable safety profile in LARC, although comparative evidence is limited and non-randomized; CIETAI provides first-in-human proof-of-concept for intra-arterial delivery of immunotherapy.