Clinical outcomes of 3-D conformal hypofractionated single high dose radiotherapy for one or two lung tumors using a stereotactic body frame

Abstract

Purpose: This study was performed to evaluate the clinical outcomes of three-dimensional (3-D) conformal hypofractionated single high dose radiotherapy for one or two lung tumors using a stereotactic body frame. Materials and Methods: Forty patients who were treated between July 1998 and November 2000, and were followed up longer than 4 months were included in this study. Thirty-one patients had primary lung cancer, and the other nine had metastatic lung cancer. The primary lung cancer was staged as T1N0M0, T2N0M0, and T3N0M0 in 19, 8, and 4 patients, respectively, and of the 31 primary lung cancer patients, 20 were inoperable, and the other 11 refused operations. All patients with primary lung cancer had a solitary pulmonary nodule less than 40 mm in diameter without any mediastinal lymph nodal involvement. The histology was adenocarcinoma in 18, squamous cell carcinoma in 9, small cell carcinoma in 1, and unconfirmed in 3 patients. The primary sites of metastatic lung cancer were colon cancer in 5, tongue cancer in 2, osteosarcoma and hepatocellular carcinoma in one patient each. Three patients with metastatic lung cancer had two tumors. The Performance Status was better than WHO grade-2 in all patients. Three-dimensional treatment planning was performed to establish the number of non-coplanar beams to maintain the target dose homogeneity within 15%, and to decrease the irradiated lung volume >20 Gy to less than 25%. All patients were irradiated using a stereotactic body frame and received 4 times 10-12 Gy single high dose radiation at the isocenter over a period of 5-13 (median=12) days. Results: Thirty-eight patients were treated with 6-10 non-coplanar static beams and the other 2 patients were treated with 7 arcs of dynamic arc conformal therapy. Forty Gy was irradiated in the initial 3 patients, and 48 Gy was irradiated in the remaining 37 patients after dose escalation. During the follow-up of 4-31 (Median=14) months, no pulmonary complications greater than an NCI-CTC criteria of grade 2 were noted. However, CT pulmonary changes (NCI-CTC criteria Grade 1) were confirmed in 90% of the patients without any severe symptoms. In addition, 36 (90%) tumors were locally controlled without any symptomatic complications. Of the 16 patients with histologically confirmed T1N0M0 stage primary lung cancer ( 11 adenocarcinomas, 4 squamous cell carcinoma and 1 small cell carcinoma ) who received 48 Gy, all tumors were locally controlled for the follow-up of 4-28months (median=12). In one patient cancer recurred in hilar lymph nodes and in the opposite lung at 6 months, and in the other two patients bone metastases were noted at 6 and 15 months without local recurrence. One patient died during the follow-up period due to intercurrent cause. Thus, the one-year local control rate was 100%, and the one-year cumulative overall survival rate was 93%, respectively. In 9 tumors with liver metastases that were irradiated with 48Gy in total, 3 tumors (33%) relapsed locally at 6-12 (median=9) months after treatment. Primary tumors other than lung tumors recurred in two patients. Conclusion: Based on the initial clinical results, we consider that 3-D conformal hypofractionated single high dose radiotherapy of 48 Gy in 4 fractions using a stereotactic body frame was safe and useful for the treatment of primary T1N0M0 stage lung tumors. Dose escalation might be necessary for patients with metastatic lung tumor.