Bevacizumab , as compared with chemotherapy alone , was associated with an increased incidence of hypertension of grade 2 or higher ( 25 % vs. 2 % ) , thromboembolic events of grade 3 or higher ( 8 % vs. 1 % ) , and gastrointestinal fistulas of grade 3 or higher ( 3 % vs. 0 % ) .