Purpose: Endobronchial brachytherapy has become more widely used to increase the total local dose of irradiation ("boost") applied for the treatment of lung cancer. Apart from treatment for local stenosis, endobronchial brachytherapy in combination with external irradiation (EI) has the potential to improve local tumor control and perhaps prolong survival, but the real benefit has not been proven yet. To evaluate the possible effects of external irradiation with an additional boost of high dose rate (HDR) brachytherapy, we conducted a prospective randomized study.
Methods and materials: Design-two groups were compared: Group 1 was treated with external radiotherapy alone (planned dose 60 Gy); Group 2 received an additional boost of HDR brachytherapy of scheduled 4.8 Gy each (at 10 mm from the source axis) before and after external irradiation. Patients-98 patients with advanced inoperable lung cancer were included in the study, 42 in Group 1 and 56 in Group 2. Both groups were comparable with respect to age, sex, tumor stage, Karnofsky performance status (KPS), and histology.
Results: A mean total external irradiation dose of 50.5 +/- 14.1 Gy in Group 1 and 50 +/- 12.5 Gy in Group 2 was applied. Group 2 received an additional dose of 7.44 +/- 2.6 Gy (at 10 mm depth) through brachytherapy. The median survival time in both groups was comparable (28 weeks and 27 weeks, respectively). In patients with squamous cell carcinoma (68 patients) Group 2 showed an advantage in median survival with borderline significance (40 vs. 33 weeks, p = 0.09). Group 2 showed also a better local tumor control in all patients; patients with squamous cell carcinoma had a significantly longer period of local tumor control. Fatal hemoptysis was the cause of death in 6 (14.2%) patients in Group 1 and 11 (18.9%) in Group 2 (p = 0.53).
Conclusions: High dose rate brachytherapy in patients with inoperable lung cancer increased local control in our randomized study when used in combination with external irradiation. Survival time was also longer, but with no clear statistical significance. This applied especially to patients with squamous cell carcinomas. There was no statistically significant difference in the incidence of fatal hemoptysis between the two groups.