Phase II, Multicenter, Open-label, Randomized Study evaluating neoadjuvant chemotherapy (FOLFOX4) in patients with stage II and III colorectal cancer with standard chemoradiation Defined by Magnetic Resonance Imaging

This is a biomedical research, phase II, multicenter, open-label, randomized study, comparing neoadjuvant CT with FOLFOX4, versus immediate preoperative chemoradiotherapy (CRT), in patients with locally advanced rectal cancer. Randomization in a 1: 1 ratio, neoadjuvant chemotherapy or chemoradiation. The purpose of the study is to evaluate the efficacy, tolerability, and comparability of new standard preoperative chemotherapy with FOLFOX4 in patients with stage II and III colorectal cancer compared to routine chemoradiation.

Inclusion Criteria:

• diagnosed with rectal adenocarcinoma;
• radiologically measurable tumor size;
• general condition (ECOG 0-2 points);
• stage II or III rectal tumor clinically (pelvic MRI and endorectal ultrasound),
• in the absence of long-term spread of the disease (confirmed by radiological examinations (computed tomography of the thorax and abdomen));
• during preoperative proctoscopy, the tumor is detected 0 -15 cm from the anus;
• Blood tests 28 days before the start of treatment:

and general blood count: neutrophils greater than 1.5x10 9 / l, platelets greater than 100 x 10 9 / l, Hemoglobin greater than 80 g / l, liver enzymes (Aspartate aminotransferase (AST/GOT), alanine aminotransferase (ALT/GPT) not more than 3 times upper limit), and renal function (creatinine up to 1.5 times the upper limit of normal) is normal; women of childbearing potential - negative pregnancy test;

• A signed informed consent form.

Exclusion Criteria:

• patients with signs of intestinal obstruction at the start of treatment;
• previous lower abdominal radiation therapy;
• other tumors over a five-year period;
• pregnant or breastfeeding women;
• men and women of childbearing potential who do not agree to use adequate contraception;
• Patient co-morbidities that would make the patient unsuitable for this study or significantly interfere with the assessment of safety and toxicity.