Abstract
Although the vast majority of early stage central type lung cancer is diagnosed fiberoptic bronchoscopically, histologically or cytologically, there are some cases in which localization can be difficult such as in cases of very early stage lung cancer, occult lung cancer or carcinoma in situ. Furthermore, some early stage lung cancer cases are ineligible for surgical treatment because of poor cardiopulmonary function.
The author performed basic studies on an experimental lung cancer series induced in dogs to evaluate the applicability of hematoporphyrin derivative (HpD) administration and-photoradiation in order to. evaluate the system's applicability in human cases. HpD has specificity for malignant tissue and can be activated by certain wavelengths of light to fluoresce or to have cytocidal effects upon the tumor cells. 2.5-3.0 mg/kg body weight of HpD was injected intravenously 48 hours prior to photoradiation in 7 dogs in which central type lung cancer had been induced by submucosal weekly injections of 20-methylcholanthrene. The laser beam used for diagnosis and location was a violet krypton ion laser, While the laser used for therapy was the red argon dye laser which yields better penetration. The laser beam was transmitted via a quartz fiber inserted through the instrumentation channel of the fiberoptic bronchoscope.
In order to observe the fluorescence emitted by the HpD when stimulated with the violet light, an image intensifier was employed, and in 6 of the 7 dogs fluorescence was recognized. No fluorescence was observed either in the cancer lesions of dogs which did not receive HpD administration or in the normal mucosa of normal dogs that did receive HpD. In 3 of the dogs photoradiation therapy was performed using the argon dye laser (100mW×10 min-200mW×20 min). The tumor disappeared in all 3 cases, and in 2 of the dogs that were sacrificed no lesion could be recognized on serial sections. No effect was seen following laser photoradiation of lesions of animals receiving no HpD or in the normal mucosa of normal animals.
Thus HpD and laser photoradiation will be applicable in the detection of tumors and extent of invasion and in the treatment of early stage central type lung cancer and in these cases may obviate the necessity of thoracotomy.
