During treatment, you will receive irinotecan by vein over one hour, once a day for 5 days in a row. This will be followed by 2 days of no study drug treatment, then 5 more days of treatment with irinotecan. This 12-day period will be followed by 9 days of rest (no study drug). This 21-day period is called a cycle of therapy. You will continue to receive treatment (cycles repeated) as long as the disease does not get worse or until maximal shrinkage of the cancer. Treatment may be taken on an outpatient basis.