Terminated after interim analysis

RATIONALE: Drugs used in chemotherapy, such as 5-fluorouracil, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing and also as a radiosensibilisant. Radiation therapy uses high-energy x-rays to kill tumor cells. 5-fluorouracil may make tumor cells more sensitive to radiation therapy. Oral 5-fluorouracil is more convenient for ambulatory patients. Giving UFT (Tegafur and Uracil) with radiation therapy before surgery may shrink the tumor so it can be removed.

PURPOSE: This phase III trial is studying how well giving UFT with radiation therapy works in treating patients who are undergoing surgery for operable rectal cancer.

Adenocarcinoma of the rectum

Stage II/stage III rectal cancer (if T4 only anal extension eligible)

Drug: UFT

Procedure: chemotherapy

Procedure: conventional surgery

Procedure: neoadjuvant therapy

Procedure: radiation therapy

Procedure: radiosensitization

Procedure: surgery

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