The INDEPSO-ISPSM Consensus on Peritoneal Malignancies-Diagnosis and Management of Peritoneal Mesothelioma.

We report the results of a consensus exercise covering the basics of management of peritoneal mesothelioma (PeM) (diagnostic evaluation, patient selection for each therapeutic modality) and some technical aspects of cytoreductive surgery (CRS) and use of intraperitoneal treatments. The modified Delphi method was employed with two rounds of voting. There were 27 questions on eight topics: diagnostic tests/preoperative work-up, extent of CRS, role of regional lymphadenectomy, hyperthermic intraperitoneal chemotherapy (HIPEC) regimens, perioperative systemic chemotherapy, role of other forms of intraperitoneal chemotherapy, surveillance after CRS-HIPEC, iterative CRS and role of palliative systemic chemotherapy. A consensus was achieved if any one option received > 70% votes (strong consensus > 90%). In round 1, 41/45 (91.11%) and in round 2, 39/45 (86.67%) panelists voted. A consensus was achieved on 22/27 (48.14%) questions (strong consensus: 33.33%). Hundred percent panelists agreed that CRS-HIPEC should be the standard-of-care for newly diagnosed PeM if the disease is completely resectable, and there is no contraindication to surgery. The panel reinforced some important recommendations of existing international guidelines on PeM, including using the cisplatin-doxorubicin combination for HIPEC, performing a total parietal peritonectomy systematically for all patients and offering neoadjuvant chemotherapy to patients with sarcomatoid and biphasic histological subtypes and for patients with PCI > 17 and Ki-67 > 9%. A consensus was reached on the indications for perioperative systemic chemotherapy. A "strong" consensus was achieved on several important issues related to the management of PeM. The treatment algorithm provided here should a useful tool to aid clinical decision making for Indian clinicians treating PeM. Supplementary Information: The online version contains supplementary material available at 10.1007/s13193-025-02272-1.