DISEASE CHARACTERISTICS:

• Histologically proven stage III adenocarcinoma of the colon that has been curatively resected within past 42 days
• No metastatic disease

• Node positive

  • No more than 4 nodes affected (Tx, N2, M0) AND/OR
  • N1 or N2 with perforation and/or occlusion
• No prior rectal cancer within 10 cm of anal margin or that was treated with preoperative radiotherapy
• No prior inflammatory disease of the intestine

PATIENT CHARACTERISTICS:

Age:

• 18 to 75

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• Neutrophil count at least 2,000/mm3
• Platelet count at least 100,000/mm3

Hepatic:

• Bilirubin less than 1.25 times upper limit of normal (ULN)
• SGOT and SGPT less than 3 times ULN
• Alkaline phosphatase less than 3 times ULN

Renal:

• Not specified

Cardiovascular:

• No myocardial infarction within past 6 months
• No insufficient cardiac function

Other:

• No other serious medical illness
• No active infection
• No other malignancy except skin cancer or carcinoma in situ of the cervix
• No psychological or social condition that would preclude study
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• Not specified

Endocrine therapy:

• Not specified

Radiotherapy:

• See Disease Characteristics

Surgery:

• See Disease Characteristics
• No prior extensive intestinal resection