RATIONALE: Using small radiation beamlets of different intensity, IMRT (intensity modulated radiation therapy) allows shaping the dose around planning target volume with better sparing of normal tissue comparing to 3D conformal radiotherapy. It allows daily delivery of higher dose to the tumor with simultaneous integrated boost (SIB), consequently shortening total treatment time with potentially better response to treatment. In advanced rectal adenocarcinoma excellent response to preoperative radiochemotherapy with complete eradication of the primary tumor observed in the histopathological specimen (pathological complete response, pCR) correlates with a favorable overall prognosis, so trying to achieve better response to preoperative treatment with higher pCR seams feasible.

PURPOSE:The hypothesis of this study is that in preoperative radiochemotherapy for locally advanced rectal adenocarcinoma shortening of the total treatment time with IMRT-SIB to 22 daily fractions concomitant with capecitabine results in an improved pCR rate from 9% (Slovenian trial) to 25%. Secondary objectives are to evaluate pathological down-staging rate, histopathological R0 resection rate, sphincter preservation rate, perioperative surgical complication rate, local control, disease-free survival (DFS), overall survival (OS), late toxicity and quality of life.

Inclusion Criteria:

• Biopsy-proven newly diagnosed primary rectal adenocarcinoma

• Locally advanced tumor fulfilling at least one of the following criteria on pelvic MRI:

  • T ≥ 3 or
  • N ≥ 1
  • Positive mesorectal fascia (MRF), i.e. tumor or lymph node one mm or less from the mesorectal fascia
  • Tumor located od 0 - 15 cm above anocutaneous junction or below peritoneum

• Age 18 years and more

• Signed informed consent

• WHO Performance Status 0-2

• Patients is considered to be mentally and physically ft for chemotherapy as judged by oncologist

• Adequate hematological, hepatic and renal function (WBC ≥ 3.0 x 109/L, neu ≥ 1.5 x 109/L, platelet count ≥ 100 x 109/L, renal clearance ≥ 50 ml/min, bilirubin ≤ 3x normal value, aspartate transaminase/alanine transaminase (AST/ALT) ≤ 2,5x normal value)

Exclusion Criteria:

• T4 inoperable tumor - extensive growth into cranial part of the sacrum (above S3) or the lumbosacral nerve roots
• Metastatic or recurrent rectal cancer
• Other co-existing malignancy or malignancy within the past 5 years, with the exception of adequately treated in situ carcinoma of the cervix or basal cell carcinoma of the skin
• Chronic bowel inflammatory disease
• Pregnant or lactating patient
• Significant heart disease (uncontrolled hypertension despite of medication (> 150/100 mmHg), New York Heart Association (NYHA) class III or IV heart disease,unstable angina or myocardial infarction within the past 1 year prior the study entry, history of significant ventricular arrhythmia requiring treatment)
• Inability to consciously sign the consent form due to physical or psychological disabilities