Stereotactic body radiotherapy response and local control rates for hepatic oligometastases.

3546 Background: Stereotactic body radiation therapy (SBRT) is a non-invasive, effective technique in the treatment of hepatic oligometastases from solid tumors. We present response and local control rates from our single institution experience. Methods: We treated 79 metastatic liver lesions from 64 different patients using stereotactic body radiation therapy. One colorectal cancer patient was treated three times and four patients were treated twice. Among the 79 metastatic liver lesions treated, 85% had prior chemotherapy. The primary cancer site included: Colorectal 66%, Non-colorectal GI 14%, Breast 6%, Ovarian 5%, NSCLC 3%, and other 6%. The mean GTV size was 37.3 (cc). The mean GTV diameter was 3.1 (cm). The median total dose was 54 (Gy) with the minimum and maximum total dose being 30 and 60 (Gy). Results: The overall local control rate was 94.2%, with estimates at 12, 24, 36, and 48 months being 96.1%, 87.9%, 87.9% and 87.9% following SBRT treatment. When comparing colorectal cancer patients vs all other primary cancer sites, the one year local control rate was 93.4% and 100%. The two and three year local control rates for colorectal cancer vs other primary cancer sites were 84.9% vs 90.9%. Best response was examined as a 4 level response (CR,PR,SD,PD) per the RECIST criteria. Overall, 67% of patients had a response, and less than 3% of patients had progression with SBRT treatment. For colorectal cancer patients, 79% had a response to treatment. Only 21% of colorectal cancer patients did not respond, however, the majority of these patients still had stable disease following treatment. Non-colorectal primary site cancers had a response in 50% of the lesions following SBRT treatment. The remaining 50% of non-colorectal primary cancers were stable following SBRT treatment and none progressed. The median dose for CR, PR, or SD was 54 Gy. The median dose for patients with progressive disease was less than 50 Gy. The observed CTC toxicities were limited with mostly grade 1-2 toxicity and only two grade 4 and one grade 5 toxicity. Conclusions: Stereotactic body radiation therapy is an effective treatment option for patients with hepatic oligometastases with a limited toxicity profile.