Early detection of lung cancer by means of hematoporphyrin derivative fluorescence and laser photoradiation

The roentgenographically occult lung cancers have proved to be predominantly squamous cell carcinoma, either in situ or with early invasion. Fiberoptic bronchoscopy is required for localization of these lesions. The localization process, however, can be difficult because these cancers, particularly the in situ lesions, may be so early as to produce no gross abnormal mucosal findings. Such cases may require repeated bronchoscopic examinations and take many months in order to result in final localization of the cancer. In recent years hematoporphyrin derivative (HpD) has been used as an endobronchial tumor indicator to facilitate the bronchoscopic localization of early squamous cell carcinoma of the central tracheobronchial tree. HpD is a mixture of porphyrin compounds that have an increased affinity for malignant tissue; it emits a characteristic red fluorescence after it has been exposed to light containing the appropriate wavelength to excite fluorescence. In this article the authors describe four different bronchoscopic fluorescence detection systems that have facilitated the bronchoscopic localization of HpD-labeled early squamous cell carcinoma of the trachea and central bronchi.