Oncological Benefits of Pressured Intraperitoneal Aerosol Chemotherapy (PIPAC) in Patients With T3-4 Gastric Cancer Cyt-

Inclusion Criteria:

* Histologically confirmed, medically operable, resectable stomach adenocarcinoma (cT3-4, any N category, M0).
* No preceding cytotoxic or targeted therapy.
* No prior partial or complete tumor resection.
* Female and male patient ≥ 18 and ≤ 75 years. Female patient with childbearing potential needs to have a negative pregnancy test within 7 days prior to study start. Males and females of reproductive potential must agree to practice highly effective contraceptive measures\* during the study. Male patients must also agree to refrain from father a child during treatment and additionally to use a condom during treatment period. Their female partner of childbearing potential must also agree to use an adequate contraceptive measure.

  \*highly effective (i.e. failure rate of \<1% per year when used consistently and correctly) methods: intravaginal and transdermal combined (estrogen and progestogen containing) hormonal contraception; injectable and implantable progestogen-only hormonal contraception; intrauterine device (IUD); intrauterine hormone-releasing system (IUS); bilateral tubal occlusion; vasectomised partner; sexual abstinence (complete abstinence is defined as refraining from heterosexual intercourse during the entire period of risk associated with the study treatments).
* ECOG = 0-2.
* Exclusion of distant metastases by CT or MRI of abdomen, pelvis, and thorax, bone scan or MRI (if bone metastases are suspected due to clinical signs). Exclusion of the infiltration of any adjacent organs or structures by CT or MRI.
* Laparoscopic exclusion of peritoneal carcinomatosis at initial staging, before start of FLOT chemotherapy
* Adequate hematological, hepatic and renal function parameters:

Leukocytes ≥ 3000/mm³, platelets ≥ 100,000/mm³, neutrophil count (ANC) ≥1000/µL Serum creatinine ≤ 1.5 x upper limit of normal Bilirubin ≤ 1.5 x upper limit of normal, AST and ALT ≤ 3.0 x upper limit of normal, alkaline phosphatase ≤ 6 x upper limit of normal For patients not receiving therapeutic anticoagulation: INR or aPTT ≤ 1.5 x ULN; for patients receiving therapeutic anticoagulation: stable anticoagulant regimen.

* Patient able and willing to provide written informed consent and to comply with the study protocol and with the planned surgical procedures.

Exclusion Criteria:

* Patient without neoadjuvant therapy or those who received a neoadjuvant therapy other than FLOT.
* Known hypersensitivity against 5-FU, leucovorin, oxaliplatin, or docetaxel.
* Other known contraindications against, 5-FU, leucovorin, oxaliplatin, or docetaxel.
* Clinically significant active coronary heart disease, cardiomyopathy or congestive heart failure, NYHA III-IV.
* Clinically significant valvular defect.
* Criteria of primary unresectability, e.g.:

Radiologically documented evidence of major blood vessel invasion or invasion of adjacent organs (T4b).

Patients with involved retroperitoneal (e.g. para-aortal, paracaval or interaortocaval lymph nodes) or mesenterial lymph nodes (distant metastases!).

* Other severe internal disease or acute infection.
* Peripheral polyneuropathy ≥ NCI Grade II.
* Patient has undergone major surgery within 28 days prior to enrollment except staging laparoscopy.
* Cirrhosis at a level of Child-Pugh B (or worse) or cirrhosis (any degree) and a history of hepatic encephalopathy or ascites.
* On-treatment participation in another interventional clinical study in the period 30 days prior to inclusion and during the study.
* Patient pregnant or breast feeding, or planning to become pregnant.
* Any other concurrent antineoplastic treatment including irradiation.