Salvage Radiotherapy in Isolated Locoregional Recurrence of Pancreatic Adenocarcinoma Post-Radical Surgical Resection: Prudent or Pointless? A Retrospective Comparative Analysis

• Published in: International journal of radiation oncology, biology, physics Vol. 120; no. 2; p. e439
• Main Authors: Erjan, A., Khan, M., Ye, X.Y., Dawson, L.A., Kim, J., Brierley, J., Wong, R.K., Yan, M., Barry, A., Lukovic, J., Kalimuthu, S., Shwaartz, C. Ganor, Tsang, E., Stanescu, T., Mheid, S., Liu, A., Hosni, A., Mesci, A.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-10-2024
• ISSN: 0360-3016
• DOI: 10.1016/j.ijrobp.2024.07.978

Isolated Locoregionally Recurrent Pancreatic Adenocarcinoma (ILRPA) accounts for 17-30 % of recurrences after radical resection, yet the role of salvage radiation (RT) in this setting remains unproven. We aimed to evaluate the impact of salvage RT on survival outcomes compared with non-salvage RT in patients with ILRPA.
We retrospectively analyzed data of patients with ILRPA post-radical resection treated at our center between 2012 and 2021. Patients were categorized into two cohorts based on whether salvage RT was administered post-recurrence. Patients who received a minimum of 30Gy in 10 fractions (BED10 ≥ 39Gy) were included for analysis. The clinical characteristics, treatments and outcomes were analyzed. Chi-square or Fisher exact test for categorical variables and student t test or Wilcoxon rank sum test for continuous variables were utilized for comparisons. Kaplan Meier Method and log rank test were performed to compare Overall survival (OS) and Progression Free Survival (PFS) between the two groups. OS and PFS were calculated from the time of locoregional recurrence until event or loss of follow-up.
Thirty-two patients were identified, 16 patients in each group. The patients and tumor characteristics were balanced between the two cohorts except for chemotherapy where RT salvage group tended to receive adjuvant/ neoadjuvant chemotherapy more than non-salvage group (P = 0.007). Median radiotherapy dose received for the salvage RT cohort was 50.4Gy (BED10 = 59.5Gy). Systemic chemotherapy was restarted in 75% either before, after or concomitant with radiation and only in 31.25% in non-salvage group (P = 0.013). Patients who received salvage RT had statistically significant better median OS and PFS than those who did not (25.2 vs 8.4 months, P = 0.0006, HR 0.25, 95% CI (0.11-0.59)), (15.6 vs 7.2 months, P = 0.0006, HR 0.26, 95% CI (0.11-0.58), respectively). Ten patients; 62.5%) developed distant metastases (DM) at least 3 months post-recurrence in the salvage RT cohort compared to five patients (31.25%) in the non-salvage RT cohort, (P = 0.08). In the salvage RT group, 10/16 patients (62.5%) maintained locoregional disease control post RT.
Salvage RT was associated with improved OS and PFS in patients with ILRPA, highlighting its potential as important treatment modality. However, the results should be interpreted cautiously given the research methodology and observed discrepancy in chemotherapy administration between the two cohorts. Further investigations are warranted to enhance survival outcomes in this challenging entity.