Clinical Results of Stereotactic Body Frame based Fractionated Radiosurgery for Primary or Metastatic Thoracic Tumors

Yoon, Sang Min; Choi, Eun Kyung; Lee, Sang Wook; Yi, Byong Yong; Ahn, Seung Do; Shin, Seong Soo; Park, Heon Joo; Kim, Su Ssan; Park, Jin Hong; Song, Si Yeol; Park, Charn Il; Kim, Jong Hoon

Abstract

PURPOSE: The aim of the study was to evaluate the treatment outcomes of stereotactic radiosurgery (SRS) using a stereotactic body frame for primary or metastatic thoracic tumors. Methods and Materials: Between January 1998 and December 2003, 101 lesions from 91 patients with primary or metastatic thoracic tumors were treated. The eligible patients included 38 with primary lung cancers and 53 with metastatic tumors from the lung, liver, gastrointestinal and other organs. All patients were immobilized using a stereotactic body frame and permitted to breathe shallowly. The respiratory movement was restricted by a diaphragm controller when the tumor movement was greater than 5 mm. Recently, for further restriction of tumor movement, an active breathing control (ABC) apparatus was used in some trained patients whose tumors located in lower lobe. Three to eight coplanar or non-coplanar photon beams were used to adequately cover the planning target volume. A dose of 10~12 Gy per fraction was given three to four times over consecutive days, to a total dose of 30~48 Gy (median 40 Gy). Local control was assessed as complete or partial responses and by a stable disease, as measured by serial chest CT scans at 1 month, and then every 3-months, and/or 18FDG-PET scans 1 month after treatment. The median follow-up period was 14 months, ranging from 4 to 56 months.
RESULTS
The overall response rate was 82%, with twenty (22%) complete and 55 (60%) partial responses. The rate of crude local control in all patients was 86% and the one- and two-year local progression free survival rates were 90 and 81%, respectively. The patients who received 48 Gy showed better local progression free survival than those that received 40 Gy or less (one-year; 100% vs. 86.7%), but this was not statistically significant. Of the 21 patients with primary lung cancer, local progression was observed in 3, at 12, 21 and 26 months after treatment, and the one- and two- year local progression free survival rates were 93 and 81%, respectively. The set-up error, as checked by CT-simulation and portal films, for every treatment was within 5 mm in all directions (X, Y and Z axis). No pulmonary complications greater than RTOG toxicity criteria grade 2 were observed.
CONCLUSION
From our experience of the stereotactic body frame based radiosurgery it appears a safe and promising treatment modality for the local management of primary or metastatic lung tumors. The optimal total dose, fractionation schedule and treatment volume should be modified after a longer follow-up of these results. Further study related to the optimal evaluation tools is also necessary to differentiate local tumor progression from radiation-induced pulmonary injury