A single institute retrospective trial of concurrent chemotherapy with SIR-Sphere versus SIR-Sphere alone in patients with chemotherapy-resistant colorectal cancer liver metastases.

Abstract

770 Background: The use of selective internal radiation therapy (SIRT) with SIR-Spheres in chemotherapy-resistant colorectal cancer liver metastases (CRC-L) has been associated with favorable progression free survival (PFS) and overall survival (OS) when given alone or concurrently with chemotherapy. However, no prospective studies exist for concurrent SIRT and chemotherapy (SIRT-CT) vs. SIRT alone. We conducted a single institute retrospective trial to compare the effect of SIRT-CT to SIRT alone on liver PFS in patients with CRC-L. Methods: Patients (pts) with CRC-L treated with SIR-Spheres at City of Hope between 2009 and 2014 were identified. CRL-L patients treated with SIRT-CT or with SIRT were excluded if they received, following radioembolization, any chemotherapy/targeted regimen on which they did not previously progress. This strategy was adopted to minimize the impact of post-SIRT systemic therapy bias on SIRT-CT/SIRT liver PFS outcome. Pts characteristics included demographics, liver involvement pattern, and lines of prior chemotherapy. Liver PFS, response rate, and toxicities were compared between SIRT-CT and SIRT arms. Kaplan-Meier estimation was used for PFS analysis. Results: 48 CRC-L pts were treated with SIR-spheres; 27 satisfied the post-SIR-spheres systemic treatment criteria (14 SIRT-CT, 13 SIRT) and were included on this study. Pts characteristics included: age (median = 62; range 52-80), sex (18 males), primary site (colon: 23), hepatic disease burden (23 bilobar), 5-FU resistance/intolerance (25/2), and extrahepatic disease (22). Pts characteristics were similar between treatment arms, except for median prior therapies (SIRT-CT = 3, SIRT = 2). No SIRT-CT or SIRT associated ≥ grade 3 toxicities were noted. Disease control rates were 84% (2/13 PR; 9/13 SD) and 14% (2/14 SD on the SIRT-CT and SIRT arms, respectively (p = 0.001). Median PFS in the liver was 176 days in the SIRT-CT group vs. 91 days in the SIRT group (p = 0.0006). Conclusions: In patients with 5-FU refractory CRC-L, SIRT-CT is associated with an increased disease control rate and a prolonged DFS in comparison with SIRT alone.