The impact of computed tomography on pretherapeutic staging in patients with laryngeal cancer: demonstration of the Will Rogers' phenomenon.

BACKGROUND The purpose of this study was to demonstrate that pretherapeutic CT of patients with primary laryngeal cancer results in stage migration, therefore affecting laryngeal cancer outcome data. METHODS We retrospectively reviewed the medical records of 90 patients with primary laryngeal cancer diagnosed between January 1, 1995, and December 31, 1997, at a university hospital. RESULTS The disease in 15 (17%) of 90 patients was reclassified into a new TNM stage after pretherapeutic CT. As a result, stage-specific survival rates improved in three of four TNM stages, even though average survival for the entire cohort did not change. CONCLUSIONS The TNM staging system is not a temporally stable classification and prediction system, because TNM assignment varies on the basis of the type of pretherapeutic evaluation. Outcome data for patients with laryngeal cancer must account for the introduction of new technologies that affect our ability to diagnose and stage this disease.