PV QA 1 - Poster Viewing Q&A 1
Purpose/Objective(s): Patients with HCC awaiting liver transplant often face prolonged wait times during which local progression can result in ineligibility per Milan criteria and delisting. As a bridge to transplant, SBRT has emerged as a treatment modality that is being more commonly implemented to ensure patients continue to meet these criteria. In this study, we aimed to determine the efficacy and safety of SBRT in such situations.
Materials/Methods: A retrospective analysis was conducted of the outcomes of 25 patients treated with SBRT who were listed for liver transplant at one institution (patient age range 41-71). Among these, 15 patients and 21 tumors went on to liver transplant and were the focus of this study. Operative reports and postoperative charts were evaluated for complications that could be related to radiation. The explant pathology findings were correlated with equivalent dose in 2 Gy fractions (EQD2) and tumor size.
Results: Median tumor size was 2.9 cm (range 0.7-4.8). Median total dose of radiation was 42 Gy (range 30-63) delivered in 5 fractions. Pathologic complete response (pCR) was achieved in 12 tumors (57%). Median interval from end of SBRT to transplant was 287 days (range 9-491). Two patients had a relatively shortened interval to transplant of 9 and 18 days and had a pathologic partial response (pPR). Of the 16 patients who had imaging prior to transplant, 12 or 75% demonstrated a clinical complete response (cCR) based on mRECIST criteria. There was a trend towards decreasing pCR rate with increasing tumor size (OR, 0.33; 95% CI, 0.099-1.07) and no significant correlation between pCR rate and EQD2 (OR, 0.99; 95% CI, 0.94-1.05). None of the patients experienced radiation related operative or postoperative complications. Of the 25 patients who were listed for transplant, the dropout rate was 28% or 7 patients. Among these, 4 died, 2 had HCC progression beyond Milan criteria, and 1 developed a new cancer diagnosis. Three patients are still listed for transplant.
Conclusion: This data demonstrates that SBRT as a bridging modality is a feasible option with a pCR rate comparable to that of other bridging modalities and no additional radiation related operative or postoperative complications. There was a higher cCR rate for patients who had imaging performed prior to transplant suggesting that there is overprediction of response based on imaging, which requires investigation into our methods of radiologic interpretation. There was no dose dependence for pCR rate, which indicates that for the tumors in this study, the radiation doses delivered were sufficiently high. However, a trend towards size dependence was demonstrated, which suggests that further evaluation of patients with a range including larger tumor sizes than in this cohort is warranted.
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