110P - Analysis for stereotactic body radiotherapy (SBRT) effect for colorectal liver metastases

Background

There are various treatment methods for colorectal metastasis, such as surgery and RFA. However, not every patient is suitable for surgery, and radiofrequency ablation is a better for lesions less than 3 cm in diameter. Under this situation, SBRT can be a choice, which has the advantages of non-invasiveness and high precision. So far, there are relatively few studies on SBRT of colorectal liver metastasis worldwide and no studies have been reported in China. Therefore, this study retrospectively analyzes patients receiving SBRT treatment of colorectal liver metastasis, to explore its effectiveness and safety.

Methods

We retrospectively analyzed CRLM patients who received SBRT treatment for liver metastases from 2017 to 2019 in our center. 20 liver lesions in total were treated. Most patients (91.7%) previously received other local treatment, and Most (91.7%) patients received first-line and above systemic treatment. The median size of treated lesions is 2.5cm(1.2∼2.5cm). The average dose was 49Gy(48∼64Gy), with average fraction number of 7(5∼10) times, equals to BED as 85.5Gy(72∼115.2Gy).

Results

The median follow-up time was 15 months (range 3-22 months). 4 lesions were observed recurrence in the irradiation field. The 6-month, 1-year local control rate was 94% and 75%, if evaluated by lesion. By univariate analysis, the local control rate of liver metastases with a maximum diameter <3 cm was significantly better than that of lesions ≥ 3 cm. The 1-year local control rate was 82% and 33%, respectively, P=0.016. The patients had a median PFS of 8 months, 6 months of PFS of 58%, and 1 year of PFS of 10%. The median OS was not reached. The 6-month OS was 92%, and the 1-year OS was 73%. None of the patients had toxicity ≥ higer grade 3.

Conclusions

SBRT treatment for liver metastases from rectal cancer has shown promising local control and survival outcomes. And the local control rate of liver metastases < 3 cm in diameter was better than that of lesions ≥ 3 cm.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Fudan University Cancer Center, Shanghai, China.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.