Immune response activation following hyperthermic intraperitoneal chemotherapy for peritoneal metastases: A pilot study

Background: Hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal metastases (PM) is considered to be feasible, safe and to improve survival.

Aim: To investigate whether an immune response is activated following HIPEC for PM.

Methods: Six patients were enrolled in this study. Peripheral blood samples were obtained from each patient prior to (day 0) and post-procedure (day 30), and used to evaluate the number of CD3⁺ total, CD3⁺/CD4⁺ T-Helper, CD3⁺/CD8⁺ cytotoxic T, CD3⁺/CD56⁺ natural killer and CD19⁺ B lymphocyte numbers, and CD4⁺: CD8⁺ T lymphocyte ratios.

Results: The total numbers of CD3⁺, CD3⁺/CD4⁺ T-Helper, CD3⁺/CD8⁺ cytotoxic T, CD3⁺/CD56⁺ natural killer and CD19⁺ B lymphocytes, and CD4⁺: CD8⁺ lymphocyte ratios were increased in all but one patient 30 d following the cytoreductive surgery-HIPEC procedure, and these increases were significant (P ≤ 0.05) for CD3⁺/CD4⁺ T Helper and CD3⁺/CD8⁺ cytotoxic T lymphocyte numbers.

Conclusion: This report provides the first evidence that HIPEC exhibits immunomodulating activity in PM patients, resulting in generalized activation of the adaptive immune response. Moreover, the majority of lymphocyte populations increased following HIPEC and continued to be elevated several weeks following the procedure, consistent with a potential authentic immunomodulating effect rather than a normal inflammatory response, to be fully characterised in future studies.