Inclusion Criteria:  Patients with confirmed histopathological diagnosis of rectal adenocarcinoma ycTNM stage II, III, or IV (AJCC 8th). Patients treated with neoadjuvant therapy. Patients that will be subject to curative intent or palliative surgery through any approach (open, laparoscopic, or robotic). Ability to sign the informed consent.  Exclusion Criteria:  Rectal cancer stage I or any stage without neoadjuvant therapy. Age < 18 and >75 years Long steroid treatment for any cause. Emergency setting. Co-existent inflammatory bowel disease. Inflammatory comorbidities (liver failure, diabetes, metabolic acidosis, acute and chronic renal failure, sepsis, AIDS, acute and chronic hepatitis, autoimmune disorders, and chronic obstructive pulmonary disease). Healthy volunteers. Other (simultaneous) neoplastic disease