Optimising utility of selective internal radiation therapy in metastatic pancreatic adenocarcinoma.

Abstract

622 Background: Selective internal radiation therapy (SIRT) using Yttrium-90 containing microspheres has established benefit for a number of cancers but there is limited data available on the utility of SIRT for the treatment of metastatic pancreatic ductal adenocarcinoma (PDAC). Methods: In this retrospective audit we identified 32 patients who received SIRT using Yttrium-90 microspheres for metastatic PDAC in 2 treatment centres. All patients received SIRT in combination with chemotherapy. Data was analysed from electronic medical records. Results: Thirty two patients with metastatic PDAC who had SIRT were identified. Patients received SIRT (median activity 1.6 GBq) in combination with chemotherapy (platinum-based; n = 23, non-platinum-based; n = 9). Three patients remain alive and 29 patients were included in the survival analysis. For the entire group, the median OS was 15 months (range 4-49), median survival from time of SIRT was 9 months (range 1-48) and median PFS from time of SIRT was 4 months (range 1-25). Median PFS (6 vs 2 months, p=0.0011) and OS (13 vs 4 months, p=0.0004) from SIRT was significantly better when SIRT was given with 1st-line therapy vs with 2nd-line and beyond. Median PFS from SIRT was significantly better (10 vs 2 months, p=0.0020) when combined with 1st line platinum-based chemotherapy (n=14) vs non-platinum based treatment (n=6). 18 month survival was 40% (n=13) with 9/13 patients having had SIRT with 1st line with platinum-based therapy. 24 month survival was 22% (n=7) with 7/7 patients having had SIRT with 1st line with platinum-based therapy. SIRT was well-tolerated with no associated 30-day all-cause mortality. Grade 3 adverse events were liver abscess (7%, n = 2), gastritis (7%, n = 2) and duodenitis (7%, n=2). Conclusions: This is the first report to analyse optimum utility of SIRT with chemotherapy in metastatic PDAC. Our data suggest SIRT in combination with 1st-line platinum agents contribute to the best outcomes in the setting and warrants further study.