Because an endobronchial valve is a one-way inspiratory airway blocker, it is hypothesized that it could be also used for controlling persistent air leaks while maintaining the drainage of secretions. The U.S. Food and Drug Administration approved in October 2008 the Spiration valve system designed to control air leaks in the lung that persist after lung surgery. This prospective observational study aims to evaluate the efficacy and safety of Spiration endobronchial valves in a prospective series of consecutive patients with a prolonged persistent air leak after anatomic surgical resection for cancer.