Prospective study of venous thromboembolism in patients with head and neck cancer after surgery: interim analysis.

Objectives: To prospectively determine the incidence of venous thromboembolism (VTE) following major head and neck surgery. At the midpoint of enrollment, an interim analysis was performed to determine if it was ethical to continue this study as an observational study without routine anticoagulation.

Design: Prospective, observational cohort study.