Univariate analysis of factors correlated with tumor control probability of three-dimensional conformal hypofractionated high-dose radiotherapy for small pulmonary or hepatic tumors

Purpose: To show the factors correlated with tumor control probability (TCP) after three-dimensional conformal hypofractionated high-dose radiotherapy (3D-CHHRT) for small pulmonary or hepatic tumors. Methods and Materials: We enrolled 34 patients with 42 lesions (13 lung carcinomas, 6 hepatocellular carcinomas, and 23 lung or liver metastases) treated with 3D-CHHRT alone, with simple immobilization devices, between July 1997 and January 2002. We prescribed 45 Gy in three fractions at the 90-100% isodose line of the planning target volume. The median follow-up period was 18 months (range, 4-46 months). We calculated the TCP using the Kaplan-Meier method and univariate analysis for the following factors: age, gender, primary site, histologic type, tumor size, and previous treatment. Results: Overall, the 2-year TCP of 3D-CHHRT was 83.6%. Local recurrence was observed in 6 lesions within 1 year after treatment. We showed that tumor size was the only significant factor to correlate with the TCP in univariate analysis. The 2-year TCP for tumors <3 cm or ≥3 cm in diameter was 95.0% and 58.3%, respectively (p = 0.0022). No severe adverse effects were observed. Conclusion: The TCP for tumors <3 cm in diameter was excellent for 3D-CHHRT. (C) 2004 Elsevier Inc.