Effects Of Adjuvant Intra-Operative Radiation Therapy After Curative Resection In Pancreatic Cancer Patients: Results Of A Randomized Study By 11 Institutions In Japan

4622 Background: To evaluate the benefits of adjuvant intra-operative radiation therapy after curative resection in advanced pancreatic cancer (APC) patients, a multi-center phase III trial was conducted by 11 participating institutions in Japan. Methods: Eligibility included pts with potentially resectable APC (duct cell origin) by image diagnosis. Patients were randomized in a 1:1 ratio to adjuvant IORT or surgery alone less than a week before surgery. Stratification factors were tumor size (TS1/TS2,3,4), location (head/body and tail), and institution. Patients who were assigned to adjuvant IORT arm received IORT after curative resection before reconstruction. IORT consisted of 25Gy with electron beam energies of more than 6MeV and was delivered by the round shaped acrylic cylinder of 6–8cm diameter. The radiation field included the tumor bed and in most cases included the celiac axis, superior mesenteric artery, and the portal vein. The primary endpoint was overall survival. The secondary endpoint was local control rate at 2 years after surgery. Assuming 65 eligible pts in each arm, the study had 0,8 power to detect 20% difference in 2-year survival rate. Results: Between 05/2002 to 12/2006 198 pts were randomized and 153 pts underwent curative resection with assigned treatment. Among the 153 pts with curative resection, seven pts revealed ineligible by the histological examination. Finally full analysis sets were 144 pts. Seventy three pts were in the IORT arm and 71 pts in the surgery alone arm. There was only one hospital death in the IORT arm. Cause of the death was intraabdominal arterial bleeding due to pancreatic fistula. Conclusions: We now are collecting the final follow up data. The final analyses will be presented at the meeting. No significant financial relationships to disclose.