Radiation Therapy Plus Irinotecan in Treating Patients With Colon Cancer

OBJECTIVES: I. Determine the maximum tolerated dose (MTD) of weekly irinotecan that will
result in an acceptable level of toxicity when given in combination with concurrent external
beam radiation therapy. II. Determine the objective response rate of these patients at the
dose level below the MTD.

OUTLINE: Patients receive irinotecan IV over 90 minutes beginning within 24 hours of
radiotherapy on days 1, 8, 15, and 22. External beam radiotherapy is administered 5 days per
week for 5.5-6 weeks starting on day 1 concurrent with chemotherapy. Cohorts of 3-6 patients
are treated until the maximum tolerated dose (MTD) has been determined. The MTD is defined as
the dose level at which the incidence of dose limiting toxicity is no greater than one-third
of the patients treated at that dose level. Once the MTD has been determined, additional
patients receive irinotecan at the dose level below the MTD with external beam radiation
therapy on the same treatment schedule as above. Patients are followed at 4 weeks after
treatment, then every 3 months for 2 years, and then every 6 months for 3 additional years.

PROJECTED ACCRUAL: Approximately 3-24 patients will be accrued into the Phase I portion of
this study. Approximately 15-25 patients will be accrued into the Phase II portion of this
study.

DISEASE CHARACTERISTICS: Histologically confirmed unresectable, incompletely resected with
gross residual disease, or locally recurrent large bowel carcinoma confined to a site
within the abdomen or pelvis All disease must be encompassable within a single radiotherapy
port No evidence of uncontrolled metastatic disease outside of the planned radiotherapy
port

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: CALGB 0-2 Life expectancy:
Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at
least 100,000/mm3 Hepatic: Bilirubin no greater than 2.0 mg/dL Renal: Not specified
Cardiovascular: No history of significant myocardial disease No New York Heart Association
class III or IV disease No unstable angina No myocardial infarction in the past 4 months
Other: No significant infection or other coexistent medical condition that would preclude
protocol therapy Maintain an adequate oral nutrition intake (at least 1,200 calories
estimated per day) No greater than 6 bowel movements per day prior to treatment No
significant nausea or emesis on optimal antiemetic therapy Not pregnant or nursing
Effective contraception required of all fertile patients

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior irinotecan
Endocrine therapy: Not specified Radiotherapy: No prior abdominal or pelvic radiotherapy
Surgery: At least 3 weeks since laparotomy or laparoscopic procedure with or without
resection