[Simple method of stereotactic radiotherapy without stereotactic body frame for extracranial tumors]

Thirty-five patients with metastatic lung cancer(46 lesions) and twenty patients with primary lung cancer (21 lesions) have been treated with a simple method of stereotactic radiotherapy (SRT) without stereotactic body frame. Tumor size ranged from 1-4 cm in diameter. We used Vac-Lok cushion(Med-Tek) as a immobilization system. To be sure to include the respiratory movement of tumor to planning target volume(PTV), every patients were examined by fluoroscopy and radio-opaque catheters with the same length of tumor movement were attached on the anterior and lateral chest wall before CT simulation. A gold grain was implanted into a tumor that was invisible on fluoroscopy, as a radiomaker. Protocol of 60 Gy/8 fractions/2 weeks and 45 Gy/3 fractions/3-6 days were mainly used. The median follow-up period was 15 months for primary lung cancer and 19 months for metastatic lung cancer. Local control rates were 91% for metastatic lung cancer, 89% for primary lung cancer and 85% for T1, 2N0M0 cases. All patients developed mild pneumonitis or fibrosis about 4.5 months after SRT just in the treatment volume. Only three patients was symptomatic.