THREE-DIMENSIONAL CONFORMAL RADIATION THERAPY FOR LUNG TUMORS USING A MIDDLE FRACTION SIZE: PRELIMINARY RESULTS

By using three-dimensional conformal radiation therapy (3D-CRT) for lung tumors, one may increase the dose to the tumor without increasing the dose to the surrounding normal lungs, thus enhance local control rates even with patients in a poor condition. We have been conducting a 3D-CRT for lung tumors using a middle fraction size. The preliminary results were analyzed. Eighteen patients with 20 lung tumors were treated with 3D-CRT between September 1999 and May 2001 according to the criteria; Tumor size: 5 cm or smaller, V20: under 20%, Middle fraction size: 3-4 Gy, No limitations to patients' age and/or respiratory status unless patient's Performance Status (PS) was 4. The mean age was 75.4 years (range; 54-86). Of these, 14 tumors in 14 patients were primary lung cancer. Five tumors in 4 patients were metastatic lung cancer colon, esophagus, thymus and lung (primary tumor was also treated with 3D-CRT) and the other one was recurrent lung cancer. The median maximun tumor diameter was 35 mm (range; 10-50). As for the treatment techniques, 6 to 10 non-coplanar fixed ports (median: 10) were used. The mean total dose and fraction size were 62 Gy (range; 51-64) and 3-4 Gy, respectively. The mean overall treatment time was 28 days (range; 24-36). One-year local control and overall survival rates of all patients were 87.7%, 94.1%, respectively. As for primary lung cancer patients, I-year local control and overall survival rates were 90.9%, 92.3%, respectively. With respect to radiation toxicity for lungs, Grade 0 and I were recognized in 9 patients and in 11 patients, respectively. No patients experienced grade 2 or greater toxicity. The results of this preliminary study suggested that our 3D-CRT using a middle fraction size for lung tumors was promising with encouraging local control rates and little lung toxicity.