Abstract

PURPOSE/OBJECTIVE(S): Following curative resection for pancreatic ductal adenocarcinoma (PDAC), there are high rates of local recurrence. The optimal treatment of patients with isolated local recurrence (ILR) - recurrence in the abdomen without distant metastases - is not known. This study evaluated stereotactic body radiation therapy (SBRT) as a treatment option for ILR.MATERIALS/METHODS: A multi-institutional retrospective analysis was performed on patients with ILR of PDAC following oncologic surgical resection treated with SBRT. Patient demographics, tumor and prior treatment characteristics, details of recurrence, SBRT treatment design and dosimetry, and patient follow-up and toxicity data were recorded from the medical record. Progression and overall survival estimates were calculated using cumulative incidence and Kaplan-Meier models, respectively.RESULTS: Between January 2010 and December 2020, 34 patients (17 males and 17 females, median age 69 years) were treated at five institutions in the United States. At the time of initial resection, most patients had T3 tumors (71%) and involved lymph nodes (71%). 31 of 34 (91%) patients underwent a Whipple procedure and 3 (9%) had a distal pancreatectomy. The R0 resection rate was 68%. 29% and 85% received neoadjuvant or adjuvant chemotherapy, respectively; and 12% and 27% had prior neoadjuvant or adjuvant radiation courses around the time of initial surgical resection. Median time to ILR was 18.7mos. The most common location of recurrence was in the pancreatic remnant or near the superior mesenteric artery. All patients underwent 5-fraction photon (28 patients) or proton (6 patients) SBRT to a median dose of 3500cGy (range 3000-4000cGy) with a median BED of 5950cGy (alpha/beta?=?10). Median follow-up after SBRT was 3.05 years. The 1-year and 2-year cumulative incidence of cancer progression were 72% (95% CI 56-93%) and 92% (95% CI 76-100%). Distant metastasis was the most common site of first recurrence (15 of 23 recurrences, 65%). 6 patients (25%) had local failure as site of first recurrence. Prior radiation was not associated with increased risk of progression after SBRT (HR 1.31 95% CI 0.56-3.07, P?=?0.54). 1-year and 2-year overall survival was 64% (95% CI 49-84%) and 40% (95% CI 25-64%), with a median survival of 1.2 years from time of SBRT. Four patients (12%) developed grade 3 toxicities within one year after completion of SBRT. There were no grade 4-5 toxicities.CONCLUSION: For treatment of PDAC ILR after surgical resection, SBRT was well tolerated and offered high rates of local tumor control with low treatment-related toxicity.

View details for DOI 10.1016/j.ijrobp.2021.07.408

View details for PubMedID 34701869