Carbon ion radiotherapy as definitive treatment in locally recurrent pancreatic cancer

PURPOSE: Data on management of locally recurrent pancreatic cancer (LRPC) after primary resection are limited. Recently, surprisingly high overall survival rates were reported after irradiation with carbon ions. Here, we report on our clinical experience using carbon ion radiotherapy as definitive treatment in LRPC at the Heidelberg Ion-Beam Therapy Center (HIT). METHODS: Between 2015 and 2019, we treated 13 patients with LRPC with carbon ions with a median total dose of 48 Gy (RBE) in 12 fractions using an active raster-scanning technique at a rotating gantry. No concomitant chemotherapy was administered. Overall survival, local control, and toxicity rates were evaluated 18 months after the last patient finished radiotherapy. RESULTS: With a median follow-up time of 9.5 months, one patient is still alive (8%). Median OS was 12.7 months. Ten patients (77%) developed distant metastases. Additionally, one local recurrence (8%) and two regional tumor recurrences (15%) were observed. The estimated 1‑year local control and locoregional control rates were 87.5% and 75%, respectively. During radiotherapy, we registered one gastrointestinal bleeding CTCAE grade III (8%) due to gastritis. The bleeding was sufficiently managed with conservative therapy. No further higher-grade acute or late toxicities were observed. CONCLUSION: We demonstrate high local control rates in a rare cohort of LRPC patients treated with carbon ion radiotherapy. The observed median overall survival rate was not improved compared to historical in-house data using photon radiotherapy. This is likely due to a high rate of distant tumor progression, highlighting the necessity of additional chemotherapy.