PIPADN is a pilot monocentric, study with a total duration of 42 months. The purpose of this study is to describe the variation of plasma ctDNA concentration between the 1st and the 3rd PIPAC session in patients with peritoneal carcinomatosis.

The improvement of life quality with this type of treatment will also be evaluated though the EORTC QLQ-C30 survey.

Each patient will have three PIPAC sessions spaced 6 to 8 weeks apart. Two blood samples will be taken during the first 3 PIPAC sessions, one the day before each procedure and a second one 24 hours afterwards.

The EORTC QLQ 30 survey will be completed by patients during the pre-operative consultation and at each post-operative consultation (about 3 weeks after PIPAC sessions).

Inclusion Criteria:

• Age ≥ 18 years old
• WHO 0 to 2
• Patient with cancer in the form of peritoneal carcinosmatois not eligible for cytoreduction surgery
• A histological diagnosis of the primary tumor or peritoneal carcinomatosis is essential.
• Patient with an indication for PIPAC for any reason (whether as part of a clinical research protocol or not). Patients with prior treatment with PIPAC are eligible.
• Patients with abdominal metastases or a single metastasis regardless of location (oligometastasis).
• For patients of childbearing age need for an effective method of contraception
• Informing patients and obtaining informed consent, dated and signed.
• Patient affiliated with a social security scheme

Exclusion Criteria:

• Age < 18 years old
• WHO > 3
• Patient who may benefit from cytoreduction surgery
• Patient with a contraindication to PIPAC
• Extra peritoneal disease with the exception of oligometastatic disease
• Persons deprived of liberty or under guardianship (including curatorship)
• Impossibility to undergo the medical follow-up of the trial for social, geographical or psychological reasons.
• For patients of childbearing age without an effective method of contraception
• Woman who is pregnant, likely to be pregnant, or breastfeeding