External irradiation and intraluminal irradiation using middle-dose-rate iridium in patients with roentgenographically occult lung cancer

Abstract 

Purpose: Therapeutic results were analyzed in 39 patients with roentgenographically occult lung cancer (ROLC), and the significance and optimal dose of this therapy were evaluated.

Methods and Materials: The subjects were 39 patients who underwent intraluminal irradiation between May 1987 and August 1999. Radiotherapy was performed by combining external irradiation with intraluminal irradiation using middle-dose-rate iridium (four 370-MBq wires) through a catheter with a spacer, which held the source in the center of the bronchus. The doses of radiation were 22–66 Gy (median value 45 Gy) by external irradiation and 10–46 Gy (median value 28 Gy) by intraluminal irradiation.

Results: The therapeutic effect was CR in 38 patients and PR in 1, and local recurrence was observed in a PR case and 3 of the 38 patients who showed CR. The 3-year and 5-year relapse-free survival rates were both 87%. No severe radiation injury was observed.

Conclusions: Considering that ROLC often occurs as multiple cancers and that many patients with ROLC have reduced lung function, radiation therapy by a combination of intraluminal irradiation and external irradiation is expected to replace surgery as the first choice for the treatment of this disease in the twenty-first century.

Keywords:  Roentgenographically occult lung cancer, Intraluminal irradiation, External irradiation, Iridium thin wire