FOCAL, HIGH-DOSE, AND FRACTIONATED MODIFIED STEREOTAXIC RADIATION-THERAPY FOR LUNG-CARCINOMA PATIENTS - A PRELIMINARY EXPERIENCE

BACKGROUND. Stereostactic radiation therapy is highly effective in the treatment of small brain metastases, regardless of the histology. Thi s suggests that small extracranial malignancies may be curable with si milar radiation therapy. The authors developed a novel treatment unit for administering such therapy. METHODS. The unit consisted of a linea r accelerator (linac), an X-ray simulator (X-S), computed tomography ( CT), and a table. The gantry axes of the three machines were coaxial a nd could be matched by rotating the table. Patients were instructed to perform shallow respiration with oxygen. The motion of the tumor was monitored with the X-S. When the motion was slight enough, the table w as rotated to the CT. To include all geometric movement on the CT imag es, each scan was made while the patient was performing shallow respir ation. After the CT positioning, the table was rotated to the Linac, a nd non-coplanar treatment was given. Beginning in October 1994, 45 pat ients with 23 primary or 43 metastatic lung carcinomas were treated. R adiation doses at the 80% isodose line were 30-75 gray in 5-15 fractio ns over 1-3 weeks with or without conventional radiation therapy. RESU LTS. The treatment was performed with no or minimal adverse acute symp toms The daily treatment time was short. During a median follow-up of 11 months, local progression occurred in 2 of 66 lesions. Interstitial changes in the lung were limited. CONCLUSIONS. With this unit and pro cedure, focal radiation therapy similar to stereotactic radiation ther apy is possible for extracranial sites. The preliminary experience app eared safe and promising, and further exploration of this approach is warranted. (C) 1998 American Cancer Society.