Published online Jun 24, 2020. doi: 10.5306/wjco.v11.i6.397
Peer-review started: December 24, 2019
First decision: February 20, 2020
Revised: April 13, 2020
Accepted: May 12, 2020
Article in press: May 12, 2020
Published online: June 24, 2020
Processing time: 181 Days and 14.3 Hours
According to current Network NCCN Guidelines, cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is considered the standard treatment for pseudomyxoma peritonei and peritoneal mesothelioma. In several clinical trials, HIPEC, in particular, resulted in survival improvements.
Thermal tumor ablation has been reported to induce a potential immunomodulatory effect, illustrated by the intense inflammatory cell response, including: Dendritic cells, neutrophils, macrophages, B and T lymphocytes and natural killer cells. The induction of this immune response might be important in increasing tumor response and improving survival.
The aim of this study was to investigate whether HIPEC for peritoneal metastases induces an immune response, which was determined by analyzing the immune population before and 30 d after HIPEC.
Peripheral blood samples were collected prior to (day 0) and following (day 30) CRS-HIPEC procedures, and immunophenotypic analysis was performed within 24 h. The levels of immunological populations were quantified by fluorescence-activated cell sorting, an antibody-based cell sorting method for heterogeneous mixtures based upon the specific light scattering and fluorescent characteristics of each antibody-labelled cell-type as reported in the literature. Immunological populations were also analyzed in stained samples, after exclusion of debris and doublets, as previously described.
The evaluation of system lymphocyte populations revealed an increase in systemic CD3+ total, CD3+/CD4+ T Helper, CD3+/CD8+ cytotoxic T, CD3-/CD56+ natural killer, CD19+ B lymphocyte levels and CD4+/CD8+ T lymphocyte CD3+/CD8+ Cytotoxic T lymphocyte ratios. Statistical significance was observed for CD3+/CD4+ T Helper and CD3+/CD8+ Cytotoxic T lymphocyte populations (unilateral paired Student’s t test, P < 0.05). These increases were observed in all but one patient, who exhibited reduced systemic lymphocyte counts post-HIPEC, consistent with severe oxaliplatin toxicity.
The results obtained provide new evidence that HIPEC induces immune system activation in pseudomyxoma peritonei patients, characterized by induction of a generalized adaptive immune response and decrease in immunosuppression. Another new finding was that the CRS-HIPEC-induced immunological effect was long-lived and lasted for several weeks, consistently with authentic immunomodulation, rather than a normal inflammatory response.
This pilot study provides the first evidence that HIPEC activates the immune response, supporting an additional immunomodulatory function for this procedure. Further studies are required to confirm these results in a large cohort study and to evaluate treatment safety, efficacy or effectiveness.