LIQUID BIOPSY FOCUSING ON CIRCULATING TUMOR CELLS AND CIRCULATING TUMOR DNA AS PRECISION MEDICINE IN GASTROINTESTINAL TUMORS

Inclusion Criteria:

Inclusion criteria:

• Age ≥ 18 years;

For locally advanced rectal cancer:

* Patients with histological confirmation of adenocarcinoma of the distal rectum who are candidates for sphincter preservation and undergoing TNT, a long-course CRT regimen, followed by CT (5-FU + consolidation oxaliplatin);
* Tumors with a location that requires rectal amputation, except for very early tumors (cT1N0);
* Absence of distant metastases (M0).

For locally advanced or metastatic stomach cancer:

* Patients with histological confirmation of adenocarcinoma of the stomach or esophagogastric junction (EGJ) (cT2-4, cN0-3, M0-1) who have not undergone any previous treatment for the disease, surgical or systemic;
* Patients who will undergo the following treatments:

  1. (T2 to T4, N+ and M0): 4 cycles of FLOT, surgery, + 4 cycles of FLOT (5-Fluorouracil, Oxaliplatin and Docetaxel);
  2. Initial cases: T2 to T4 N0: Surgery followed by adjuvant chemotherapy: CAPOX (capecitabine + oxaliplatin) or FOLFOX (5-Fluorouracil + capecitabine) - 8 cycles;
  3. Initially unresectable T4N3: If PDL1+ and CPS \> 5: CT (FOLFOX or XELOX) + nivolumab. If HER-2 + XELOX or FOLOFX + transtuzumab - after 8 cycles evaluate resectability;
  4. Metastatic disease: if HER2 negative - XELOX or FOLFOX with Nivolumab or pembrolizumab. If HER2 positive XELOX or FOLFOX with trastuzumab + pembrolizumab.

For localized or metastatic pancreatic cancer:

* Patients with histologically confirmed pancreatic adenocarcinoma (cT1-4, N0-2, M0-1) who have not undergone any prior surgical or systemic treatment for the disease.
* Patients who will undergo the following treatments:

  1. T1 to T3, N0 to N2 - resectable: Surgery followed by 12 cycles of FOLFIRINOX (oxaliplatin, 5-fluorouracil and irinotecan)
  2. Borderline resectable: Neoadjuvant chemotherapy with FOLFIRINOX for 8 cycles and surgery
  3. Unresectable disease - locally advanced: FOLFIRINOX for 12 cycles or Gemcitabine + nanoparticle paclitaxel for 8 cycles

Exclusion Criteria:

* Mid-rectum tumors or tumors with microsatellite instability.
* Stomach tumors or early EGJ (cT1N0)
* Patients who have undergone prior treatment or any surgical intervention in the last 30 days.