Evaluation of the spatial diffusion of methylene blue injected in vivo by bronchoscopy into non-small cell lung carcinoma.

Background: Due to smoking prevalence and the poor efficiency of current therapy, lung cancer is the leading cause of cancer death in developed countries, and its worldwide incidence is steadily increasing. Gene therapy by direct intratumoral injection of different types of gene constructs through a fiberscope has been suggested and evaluated in a few patients.

Objective: It was the aim of this study to observe the actual volume of diffusion within a lung tumor using a color marker.

Methods: Using bronchoscopy, just after anesthesia, methylene blue was injected into patient tumors. These patients subsequently underwent surgery for treatment of a non-small cell lung cancer.

Results: We observed a diffusion of methylene blue in resected lung tumors with a mean infiltrated versus noninfiltrated tumor volume ratio of 29 +/- 15%. Interestingly, some large tumor areas were not stained. At the cellular level, a preferential diffusion of the dye was observed in the tumor stroma compartment versus the tumor cellular compartment, where basal cells were more frequently and strongly labeled than the other tumor cells.

Conclusions: Since a cancer is cured when most, if not all, cancer cells are killed, the preliminary evaluation of the spatial diffusion of any injected gene construct should be carried out as a first step in any cancer type.