Inclusion Criteria:

- Patients with histologically confirmed rectal cancer.

- Candidates for preoperative radiotherapy.

- Primary tumor at least 3cm and clinical stage of T2, T3, or T4 and any N according to
the Astler-Coller modification of the Dukes staging system.

- Eastern Cooperative Oncology Group (ECOG) performance status less than 2.

- Diagnosis of rectal cancer should be no more than 90 days from start of therapy.

- Evaluation at the H. Lee Moffitt Cancer Center.

- Recovery from prior surgery and life expectancy at least 3 months.

Exclusion Criteria:

- A primary tumor totally excised.

- Recurrent rectal cancer that failed initial treatment.

- Exposure to topotecan, infection, immunodeficiencies, conditions of the
gastrointestinal (GI) tract which would affect absorption, medication that maintains
motility/gastric emptying.

- Any concomitant malignancy within the last five years.

- Severe medical problems unrelated to the malignancy which would limit compliance
with the study.

- Patients of child bearing potential.

- Not practicing adequate contraception.

- Patients who are pregnant or lactating.

- Use of an investigational drug within 30 days or 5 half-lives of the first dose.