Stereotactic body radiation therapy using three fractions for isolated lung recurrence from colorectal cancer

Objective: To determine the feasibility of stereotactic body radiotherapy (SBRT) using 3 fractions for isolated colorectal lung metastases. Methods: From June 2003 to December 2006, 13 cases of isolated pulmonary metastasis from colorectal cancer were treated by SBRT due to an inoperable state (7 patients), or the patient's refusal to undergo surgical excision (6 patients). All patients underwent chemotherapy for salvage treatment. SBRT doses ranged from 39 to 51 Gy in 3 fractions. Nine patients had a solitary lesion, 3 patients had 2 lesions, and 1 patient had 3 lesions. Median tumor volume for the 18 lesions was 5.9 ml (range 1.6-45 ml). Results: Follow-up duration was 15-57 months. Three-year overall survival, local control and progression-free survival rates were 64.7, 52.7 and 11.5%, respectively.Univariate analysis showed that total internal target volume was a significant prognostic factor for local control. During the follow-up, 11 of the 13 patients experienced local recurrence, distant metastasis or both. The most frequent site of failure was in a nontargeted lung region. No severe complication was attributed to SBRT. Conclusion: Our study suggests the potential feasibility of SBRT for selected patients with 1-3 small metastatic nodules. A further larger-scale study is required to define the indications for SBRT in cases with isolated pulmonary metastasis from colorectal cancer.