<qa>  What is the duration of bevacizumab IV?Patients receive bevacizumab IV over 30-90 minutes on day 1 courses 1-4. Beginning with course 2, patients also receive fluorouracil IV continuously on days 1-14 and undergo external beam radiotherapy on days 1-5 and 8-12. Treatment repeats every 2 weeks for 4 courses in the absence of disease progression or unacceptable toxicity. 