Carbon Ion Radiation Therapy for Locally Advanced Pancreatic Cancer

Study subjects will receive carbon ion radiotherapy (CIRT), with daily fraction sizes of 3 GyE. The total CIRT dose will increase with each dose level. Subjects in dose level 1 and 2 will receive photon radiotherapy as well.

"Combined chemotherapy regimen before/after radiotherapy: gemcitabine-based chemotherapy regimen.~All patients will have received 2-4 cycles of gemcitabine-based chemotherapy prior to study registration, with post-chemotherapy imaging demonstrating locally-advanced disease without evidence of distant metastatic disease spread. Patients who received chemotherapy regimens other than those listed above may be considered for study enrollment at the discretion of the lead investigators, provided that all other eligibility criteria are satisfied. Gemcitabine-based chemotherapy will be continued starting 3-5 weeks after completion of radiotherapy until disease progression, intolerability, or the patient's decline of chemotherapy."

"Combined chemotherapy regimen before/after radiotherapy: gemcitabine-based chemotherapy regimen.~All patients will have received 2-4 cycles of gemcitabine-based chemotherapy prior to study registration, with post-chemotherapy imaging demonstrating locally-advanced disease without evidence of distant metastatic disease spread. Patients who received chemotherapy regimens other than those listed above may be considered for study enrollment at the discretion of the lead investigators, provided that all other eligibility criteria are satisfied. Gemcitabine-based chemotherapy will be continued starting 3-5 weeks after completion of radiotherapy until disease progression, intolerability, or the patient's decline of chemotherapy."

"Combined chemotherapy regimen before/after radiotherapy: gemcitabine-based chemotherapy regimen.~All patients will have received 2-4 cycles of gemcitabine-based chemotherapy prior to study registration, with post-chemotherapy imaging demonstrating locally-advanced disease without evidence of distant metastatic disease spread. Patients who received chemotherapy regimens other than those listed above may be considered for study enrollment at the discretion of the lead investigators, provided that all other eligibility criteria are satisfied. Gemcitabine-based chemotherapy will be continued starting 3-5 weeks after completion of radiotherapy until disease progression, intolerability, or the patient's decline of chemotherapy."

"Combined chemotherapy regimen before/after radiotherapy: gemcitabine-based chemotherapy regimen.~All patients will have received 2-4 cycles of gemcitabine-based chemotherapy prior to study registration, with post-chemotherapy imaging demonstrating locally-advanced disease without evidence of distant metastatic disease spread. Patients who received chemotherapy regimens other than those listed above may be considered for study enrollment at the discretion of the lead investigators, provided that all other eligibility criteria are satisfied. Gemcitabine-based chemotherapy will be continued starting 3-5 weeks after completion of radiotherapy until disease progression, intolerability, or the patient's decline of chemotherapy."

During this study, the prescribed dose shall be administered according to the dose escalation shown in the table, starting with dose level 1. The carbon ion dose shall be gradually escalated while gradually reducing the dose of photons until eventually administering a full dose of 56 GyE/14 Fx carbon ions (fractional dose of 4 GyE). Dose escalation will be performed in parallel for two patient groups: patients whose pancreatic tumors are greater than 5 mm from the duodenum (Group A) and those whose tumors are within 5 mm of the duodenum (Group B). Enrolled patients will be monitored for 90 days after radiotherapy starts for any acute toxic reaction and to explore the maximum tolerated dose, in addition to being observed for any related long-term toxic reactions in accordance with the protocol.