A Randomized Crossover Clinical Trial to Evaluate the Efficacy of Oral Transmucosal Fentanyl Citrate in the Treatment of Dyspnea on Exertion in Patients With Advanced Cancer … View this article – A Randomized Crossover Clinical Trial to Evaluate the Efficacy of Oral Transmucosal Fentanyl Citrate in the Treatment of Dyspnea on Exertion in Patients With Advanced Cancer