Stereotactic Body Radiotherapy of Colorectal Cancer Oligometastases to the Liver: Three Years Follow-Up.

BACKGROUND

Liver resection remains the gold standard treatment for colorectal cancer (CRC) liver metastases, while stereotactic body radiotherapy (SBRT) offers an alternative for patients with unresectable metastases. However, the precise indications for SBRT, optimal radiation doses, and treatment regimens have yet to be definitively established.

METHODS

A total of 91 patients with 152 lesions underwent SBRT, receiving a total dose ranging from 40 to 60 Gy delivered in 4-5 fractions per lesion, with a median dose of 50 Gy.

RESULTS

The three-year local control (LC) and overall survival (OS) rates were 62.6% and 45.1%, respectively. No cases of Grade ≥ 3 toxicity were observed. Factors negatively affecting LC included metastasis diameter ≥ 2.7 cm and number of metastases ≥ 3, with hazard ratios (HR) of 2.73 and 2.24, respectively. A biologically effective dose (BED) of ≥137.7 Gy was associated with a significant improvement in local control (LC) (HR 0.25), a finding that was also confirmed by the inverse probability of treatment weighting (IPTW) analysis. Significant predictors for poorer OS included RAS gene mutations, metastasis diameter ≥ 2.6 cm, and synchronous metastases, with HRs of 2.27, 2.03, and 2.11, respectively. Landmark analysis demonstrated that local recurrence within 12 months after SBRT significantly reduced OS (HR 2.68).

CONCLUSIONS

SBRT is a safe and effective method for achieving local control of CRC liver oligometastases. Further research is warranted to optimize treatment protocols and refine patient selection criteria.