High dose stereotactic body radiotherapy using three fractions for colorectal oligometastases.

BACKGROUND AND OBJECTIVES

This study evaluated the treatment result of high dose stereotactic body radiation therapy (SBRT) for colorectal oligometastases.

METHODS

Between 2003 and 2009, 41 patients with 50 lesions confined to one organ from colorectal cancer (CRC) and treated with high dose SBRT ≥45 Gy were retrospectively reviewed. Lymph nodes (LNs) (18 patients) were the most frequent sites followed in order by lung (12) and liver (11). SBRT doses ranged from 45 to 60 Gy in three fractions (median 48 Gy). The cumulative gross tumor volume (GTV) ranged from 2 to 123 ml (median 13 ml).

RESULTS

The median follow-up period from the SBRT date was 28 months (range, 6-65 months). The 3-year local control and overall survival rates were 64 and 60%, and the respective 5-year rates were 57 and 38%. Cumulative GTV and SBRT dose were statistically significant prognostic factors for local control. The grade 3 or 4 complications occurred in three patients (7%).

CONCLUSIONS

High dose SBRT for colorectal oligometastases was found to produce results comparable with surgical series. To improve local control, dose higher than 48 Gy are recommend when possible, but further study will be required to define the optimal normal tissue constraints and acceptable toxicity.