Inclusion Criteria:  For Unesectable PM Group:  Age ≥ 21 years old ECOG < 3 Fit for systemic chemotherapy treatment Adequate bone marrow function (haemoglobin ≥ 8.0 mmol/L, neutrophils ≥ 1.5X109/L, platelets ≥ 100X109/L Adequate renal function (e-GFR > 30mls/min for patients undergoing PIPAC with oxaliplatin; e-GFR > 60mls/min for patients undergoing PIPAC with Doxorubicine/Cisplatin) Adequate liver function (Total bilirubin < 1.5 upper limit of normal; ALT and AST< 3 upper limit of normal) No contraindications to chemotherapy agents oxaliplatin, doxorubicin/ cisplatin No contraindications to general anaesthesia and diagnostic laproscopy procedure Normal left ventricular ejection fraction (for patients undergoing PIPAC with doxorubicin/ cisplatin) Histological/ cytological proof of PM from GI, HPB, Gynaecology, Breast, Sarcoma primaries Peritoneal-dominant metastatic disease  For the Extensive PM Group:  All the above mentioned criteria as for the unresectable group, with the addition of the following:  Not suitable for curative cytoreductive surgery (CRS) & hyperthermic intraperitoneal chemotherapy (HIPEC) surgery after diagnostic laproscopy - PCI > 18 in LGI, PCI > 6 in UGI ECOG < 3 In UGI PM patients, progression while on bidirectional chemotherapy  Exclusion Criteria:  Patient is medically unfit for surgery due to concurrent medical comorbidities, including but not limited to intestinal obstruction, multiple sites of metastases Any medical or psychiatric condition(s) which would preclude informed consent Patient is pregnant or nursing GI PM patients with PCI >6 but are treatment naive (these patients should undergo standard treatment - bidirectional intravenous and intraperitoneal chemotherapy)