Trial Testing Ftorafur (UFT) Associated With Neoadjuvant Radiotherapy Versus Radiotherapy Alone in Rectal Adenocarcinoma

DISEASE CHARACTERISTICS: * Histologically confirmed invasive adenocarcinoma of the rectum , M0, lower side \< 10 cm from anal verge * T3 or T4 disease (T4 exclusive anal extension ) PATIENT CHARACTERISTICS: Performance status * ECOG 0-2 OR * Zubrod 0-2 Life expectancy * Not specified Hematopoietic * Absolute neutrophil count \> 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 Hepatic * Bilirubin \< x2 UNL Renal * Creatinine \< 150 µMol/L Gastrointestinal * No history of inflammatory bowel disease * No history of difficulty or inability to take or absorb oral medications Neurologic * Not specified Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No other malignancy within the past 5 years except curatively treated basal cell skin cancer or carcinoma in situ of the cervix * No history of psychiatric conditions or diminished mental capacity that would preclude study compliance or giving informed consent PRIOR CONCURRENT THERAPY: Chemotherapy * No prior chemotherapy Radiotherapy * No prior radiotherapy to the pelvis Other * No other concurrent investigational drugs * No other concurrent anticancer treatment