Effect of Endobronchial Radiation Therapy on Malignant Bronchial Obstruction: DISCUSSION
Several therapeutic modalities are currently available for malignant airway occlusion. These include external beam radiation, laser therapy, and endobronchial radiation. To our knowledge, no randomized study has evaluated these modalities prospectively. Although laser therapy achieves immediate airway recanalization, the duration of response is unlikely to be long, as considerable endobronchial as well as extrabronchial tumor is likely to be left untreated. A recent study suggested that when compared with external beam radiation, “faster palliation with fewer side effects is probably achieved with laser therapy,” but no supporting data were presented.
External beam radiation can successfully reverse atelectasis and pneumonitis in 21 to 61 percent of patients. In the largest series reported to date, 23 percent of 330 patients had improvement of atelectasis following external radiation. In a recent study of 57 patients, 21 percent achieved resolution of atelectasis and a clear dose response relationship was discerned. However, at follow-up bronchoscopy, none of 14 patients had clearance of endobronchial tumor. These authors therefore concluded that high doses of external radiation are required for reaeration and despite this, the response rate is poor and complications are frequent.
Endobronchial radiation, on the other hand, as seen in our study, is very successful in achieving roentgenographic reaeration and in patients undergoing repeated bronchoscopy, a high complete response rate is noted. This is probably a function of the high tumor dose delivered in a relatively short time interval. The complication rate is acceptable and can be further lowered by excluding very-high-risk patients.
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Other studies have combined endobronchial radiation and laser excision, but the results are not superior to the endobronchial radiation series reported by us.
With the need for general anesthesia, the possible risk of intraoperative death, the intrinsic limitation of laser to have no impact on extrabronchial disease, and lack of proven superiority to endobronchial radiation, we question the need for laser excision in these patients. The recent availability of high-dose rate remote after- loading machines15 has tremendously simplified endobronchial radiation and made it very safe for personnel. This technology also has the added advantage of being performed in an outpatient setting and thereby results in considerable savings of health care dollars.
In our series of 55 implants, seven major long-term complications were encountered. The exact quantification of tracheovascular fistulae is difficult in patients not undergoing autopsies. Hemoptysis as the terminal event is not an uncommon occurrence in these patient, even without implantation. We have scored all deaths secondary to hemoptysis as complications of our therapy. A total of three tracheovascular fistulae in 55 implants (3/55 = 5.5 percent) in 52 patients (3/ 52 = 5.8 percent) were noted. These resulted in the immediate death of the three patients. An additional patient also died of hemoptysis during laser vaporization and is not scored as a complication of radiation therapy. Interestingly, of the seven major complications, four patients had laser vaporization in addition to the other therapies. Since only 12 patients had laser + EBRT, our study suggests that the combination of external radiation, EBRT, and laser may possibly lead to a higher complication rate. However, these patients had multiple courses of therapy because of advanced tumor that could also have been responsible for the increased complication rate. Preimplant laser therapy should probably be reserved for only those patients in whom EBRT would not be feasible without first creating a channel with laser. silagra tablets
In the setting of recurrent disease, malignant airway occlusion results in a median survival of only five months. Most patients have progression at distant sites and, therefore, endobronchial therapeutic maneuvers are unlikely to significantly impact overall survival.
We conclude that endobronchial radiation is a highly effective palliative modality that provides excellent control of local symptoms for a significant duration of a patients remaining life span.