Combination Chemotherapy Plus Radiation Therapy in Treating Patients With Stage II or Stage III Anal Cancer

DISEASE CHARACTERISTICS:

* Histologically proven nonmetastatic anal cancer

  * Anal/rectal junction OR
  * Anal/cutaneous junction with the majority of the tumor in the anal canal, above the junction
  * Epidermoid cancer (well-differentiated, fairly differentiated, or basaloid) OR
  * Cloacogenic cancer
  * Stage II or III

    * T2 at least 4 cm OR
    * T3 OR
    * T4, N0-3, M0 OR
    * T1, N1-3 OR
    * T2 (less than 4 cm), N1-3
* Tumors at least 4 cm in greatest dimension and/or tumors with lymph node invasion must be nonmetastatic by ultrasound
* No prior surgery to remove tumor

PATIENT CHARACTERISTICS:

Age:

* 80 and under

Performance status:

* WHO 0 or 1

Life expectancy:

* Not specified

Hematopoietic:

* WBC at least 2,000/mm\^3
* Platelet count at least 100,000/mm\^3
* Hemoglobin at least 11 g/dL (transfusion allowed)

Hepatic:

* Not specified

Renal:

* Creatinine no greater than 1.5 mg/dL

Cardiovascular:

* No cardiac condition contraindicating use of fluorouracil

Other:

* No prior malignancy within 5 years except squamous cell or basal cell skin cancer or carcinoma in situ of the cervix or breast
* No other serious medical or psychological condition
* No serious immunosuppression

PRIOR CONCURRENT THERAPY:

Biologic therapy:

* No prior biologic therapy

Chemotherapy:

* No prior chemotherapy

Endocrine therapy:

* No prior endocrine therapy

Radiotherapy:

* No prior pelvic or inguinal radiotherapy

Surgery:

* See Disease Characteristics
* No prior definitive colostomy