The differential diagnosis of primary lung cancer: inter-observer agreement and contribution of specific diagnostic procedures.

In order to investigate inter-observer variability in the differential diagnosis of primary lung cancer among women and the contribution of specific diagnostic procedures to this diagnosis, a group of 449 suspect cases of this disease was studied. Based on a standard dossier (including clinical data and the reports, if present, of radiology, bronchoscopy and histology) six different physicians independently judged, for each woman, at each diagnostic step, the presence of a primary lung cancer. A final consensus was organized in order to define the true cases. Radiology and especially histology seem to give the most important contribution to the diagnosis. On the other hand bronchoscopy seems to be useful mainly as a guide for biopsy. A predictive value of 90% was found when both radiology and bronchoscopy were positive; in the other cases histology seems to be needed to reach an adequate discrimination. Inter-rater agreement increases with an increasing amount of information but is not very high even when histology is available.