POP-UP: a Single-arm, Two-cohort Study: an 8-week Trimodal Pre-habilitation Program for Patients With Pancreatic Ductal Adenocarcinoma and Oesogastric

Inclusion Criteria: 1. Signed and dated patient informed consent form (ICF) and willingness to comply with all study procedures and availability for the study duration, 2. Histologically or cytologically proven, localized PDAC or OGC, 3. Indication to a neoadjuvant treatment with triplet chemotherapy for ≥ 4 cycles (8 weeks) validated by the multidisciplinary board, Note: Patient treated for PDAC, dose reduction of oxaliplatin or irinotecan is authorized. 4. Age \> 18 years; If aged ≥ 75 years: G8 score must be ≥ 14 and if \< 14 validation of oncogeriatric specialist, 5. Eastern Cooperative Oncology Group performance status (ECOG PS) of 0-1 at the inclusion visit, 6. No prior treatment for PDAC or OGC before starting chemotherapy (FLOT or FOLFIRINOX), 7. At least one measurable or evaluable lesion as assessed by Computerized Tomography scan or Magnetic resonance imaging according to RECIST 1.1 and feasibility of repeated radiological assessments, 8. Adequate hematologic and end-organ function allowing the triple combination chemotherapy protocol, 9. Registration in a national health care system (PUMa - Protection Universelle Maladie included). Exclusion Criteria: 1. Evidence of metastatic disease at imaging (validated in multidisciplinary team evaluation), 2. Histology of other than adenocarcinoma, 3. Any medical (including cardiovascular, respiratory, psychiatric, musculoskeletal, or neurological) condition contra-indicating exercise practice, 4. Patients with medical contraindication to surgery due to general condition or comorbidities 5. Pregnancy or breast-feeding, 6. Patient under a legal protection regime (guardianship, curatorship, judicial safeguard) or administrative decision or incapable of giving his/her consent,