High Dose-Rate Intraluminal Irradiation in Bronchogenic Carcinoma: Discussion
The most common symptoms caused principally by an endobronchial component due to bronchogenic carcinoma include hemoptysis, shortness of breath, cough, and postobstructive pneumonia. Endobronchial irradiation is a relatively simple procedure enabling delivery of an effective tumoral dose to a small volume without exceeding normal tissue tolerance. The value of endobronchial irradiation is especially evident in patients presenting with recurrent tumors who received prior high-dose external-beam irradiation.
Several authors have shown that patients treated with either low dose-rate or high dose-rate endobronchial irradiation achieved good to excellent palliation of symptoms with little morbidity. Intraluminal brachytherapy of endobronchial lesions was first performed with the Henschke afterloading technique in 1961. Iodine 125 encapsulated sources replaced previously used radon 222, reducing many radiation safety problems. These radioactive seeds were introduced into hollow needles which were inserted one at a time through the bronchoscope into the tumor. With this technique, it was difficult to control the depth of insertion of the sources. In addition it was not possible to place more than one needle at a time through the rigid bronchoscope. Furthermore, these interstitial endobronchial brachytherapy treatments were associated with a high incidence of edema, subsequent bronchial obstruction, and bleeding. Afterloading techniques with low-dose irradiation using iridium 192 have provided good local control and palliation; however, the difficulties associated with these treatments appear greater than with HDR techniques and are associated with prolonged hospitalization requiring a considerable amount of both supportive and nursing care, which then imposes inherent radiation safety difficulties. canadian neighbor pharmacy
Remote afterloading was first introduced by Henschke in the 1960s. This method of treatment had many advantages over the previously described interstitial implantation technique. Remote afterloading allowed intraluminal irradiation without the trauma associated with interstitial implantation. The remote afterloading reduces radiation exposure to the staff and enables a high dose to be delivered over a short treatment time. Patients may, therefore, be treated on an outpatient basis. Furthermore, the technique more readily provides for dose optimization by easily programming dwell times for the radiation source at particular anatomic locations based on the tumor bulk encountered at that particular spot. This enables greater individualization of dose and greater flexibility in planning treatment.
High dose-rate endobronchial irradiation has been used increasingly in many centers throughout the country to treat both primary and recurrent endobronchial disease. Studies have shown good to excellent symptomatic and objective responses overall. Response rates range from 60 to 90 percent. The results of our study revealed similar symptomatic improvement. Subjective improvement with relief of symptoms was achieved in all patients presenting with hemoptysis. Significant reduction in dyspnea and cough were also seen. In addition, most patients had a durable response for at least 6 months after brachytherapy. This compares favorably with other earlier reports. Also noted was a complete pathologic response on follow-up in all ten patients undergoing bronchoscopy after their final endobronchial application. Radiographic clearing, re-aeration, or significant improvement in atelectasis or infiltrate was documented in 44 percent.