Results and prognostic factors of hypofractionated stereotactic radiation therapy for primary or metastatic lung cancer.

Introduction: Retrospective analyses were performed on the patients with primary or metastatic lung cancer, who were treated with hypofractionated stereotactic radiation therapy (HSRT).
Methods: HSRT was applied to 43 patients since 2001 till 2007: 16 patients were with stage I primary lung cancer and 27 were with metastasis. Radiation was delivered in five consecutive daily fractions. The total doses were 50 Gy to 8 patients and 60 Gy to 35 patients. The median follow-up period was 21 months (range, 3-87 months). The effects of tumor size (<2.5 cm versus >or=2.5 cm) and radiation dose (50 Gy/5 fractions versus 60 Gy/5 fractions) on local tumor control were evaluated.
Results: Local tumor progression occurred in three patients (6.9%). The 5-year local progression-free survival and cancer-specific survival rate were 89.4 and 53.3%, respectively. Tumors <2.5 cm resulted in higher crude local tumor control rate than tumors more than or equal to 2.5 cm (100.0% versus 82.3%, p = 0.05). In tumors more than or equal to 2.5 cm, the local tumor control rate was 66.7% with 50 Gy/5 fractions and 85.7% with 60 Gy/5 fractions (p = 0.46).
Conclusions: In HSRT for primary or metastatic lung cancers, smaller tumor size was significant prognostic factor for higher local control. Higher radiation dose than 50 Gy/5 fractions was needed in tumors more than or equal to 2.5 cm for local tumor control.