Neoadjuvant intraperitoneal chemotherapy in high-risk and cytology positive gastric cancer: a systematic review

Background: Gastric cancer has a risk of early transcoelomic spread. Despite perioperative chemotherapy and surgery, peritoneal recurrence is a frequent contributor to mortality. The addition of neoadjuvant normothermic intraperitoneal chemotherapy (IPC) allows early treatment of microscopic disease. Our study aims to systematically evaluate the safety and efficacy of neoadjuvant IPC in patients with gastric cancer who are at high risk of peritoneal recurrence. Methods: A systematic review was conducted according to the PRISMA guidelines. Embase, PubMed, Web of Science and Scopus were searched for relevant papers. The primary outcomes were the rates of disease-free (DFS) and overall survival (OS) among patients treated with neoadjuvant IPC. Secondary outcomes focused on adverse effects and toxicity. Results: Overall, 562 manuscripts were screened and 7 papers were included, totalling 158 patients. For cytologypositive patients, the addition of IPC led to a conversion to negative cytology and radical surgery in 78-89 %. This was associated with relatively high DFS and OS. Peritoneal-specific recurrence was higher in cohorts who initially had cytology-positive disease (63-69 %) compared to those who did not (0-29 %). Our data suggest that OS is lower in patients who were initially cytology-positive compared to cytology-negative disease. Importantly, neoadjuvant IPC did not appear to significantly increase treatment-related adverse events. Conclusion: Our results suggest that the neoadjuvant IPC has efficacy and is safe, with high rates of cytology conversion (in cytology-positive disease), low rates of peritoneal recurrence (in locally advanced disease). This was associated with substantial improvements in DFS and OS, compared to current standard treatment regimens.