Searching for treatment alternatives, we hypothesized that the basic pathogenesis of our patient’s condition might just be equivalent to that suggested for the coronary arteries restenosis; we suspected that in both conditions a similar mechanism of response to injury, manifested by exaggerated proliferation of either neoin-tima or granulation tissue around the disrupted epithelium. Encouraged by the seemingly effective endovascular procedure, we offered the patient endobronchial HDR brachytherapy. Early reports of rapamycin-covered stents used in coronary revascularization are promising in preventing neointimal growth, and it will be most interesting to examine their use in endobronchial stents.
The first report on the use of endobronchial HDR brachytherapy for nonmalignant causes, still in press at the time the treatment of our first patient was tailored, was done by Kennedy. In this report, a similar approach was chosen in two patients with lung transplantation, in whom hyperplastic bronchial obstruction developed at the site of the anastomosis, and in whom balloon dilatation, laser application, and stent placement failed to restore protracted patency. This group used a lower dose (3 Gy) than we did, although in one patient two sessions were required. The authors described a significant clinical improvement and patent airways, 6 months and 7 months after the procedure, in both patients.
Both reports, that of Kennedy and the present study, demonstrate the effectiveness of endobronchial HDR brachytherapy in preventing granulation tissue formation reactive to a bronchial stent. In spite of the impressive clinical results, data regarding the potential mechanism underlying these phenomena are still scarce. This is even more surprising considering the enthusiasm surrounding the congruent endovascular brachytherapy field, which has resulted in various clinical and laboratory studies. Indeed, clues regarding the biological effects of irradiation on the injured epithelium covering the bronchial wall emerge almost exclusively from the vascular model.
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