Impact of hyperthermic intrathoracic chemotherapy during cytoreductive surgery with diaphragmatic resection

Diaphragmatic involvement during cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) is frequent and often necessitates full-thickness resection. This procedure carries a risk of pleural dissemination, and hyperthermic intrathoracic chemotherapy (HITHOC) has been proposed as a prophylactic measure. While HITHOC has been studied in malignant pleural mesothelioma and thymic tumors, evidence is lacking for pleural metastases from peritoneal surface malignancies.

We retrospectively analyzed 465 CRS/HIPEC procedures performed between 2006 and 2023. Patients who required diaphragmatic resection (n = 44) were included and stratified according to whether they received concomitant HITHOC (n = 20) or not (n = 24). Demographic, perioperative, and oncological outcomes were compared between groups.

Pleural invasion was identified in 30.5 % of diaphragmatic specimens. No pleural recurrence was observed in the HITHOC group, while one recurrence occurred in the HIPEC-only group (4.1 %). Overall survival did not significantly differ between groups (median 31 months with HITHOC vs. 63 months without; p = 0.07). Pleural invasion status was not associated with inferior survival (median 47 vs. 54 months; p = 0.54). HITHOC was associated with a significantly higher reoperation rate and longer ICU stay.

Diaphragmatic resection during CRS/HIPEC frequently reveals pleural invasion, yet pleural recurrence remains rare. Prophylactic HITHOC did not improve survival but was associated with increased perioperative morbidity. A selective approach, reserving HITHOC for cases with macroscopic or histologically confirmed pleural involvement, appears safe and may minimize unnecessary complications. Larger prospective studies are warranted to clarify its role in this setting.