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Session Item

Sunday
August 29
16:45 - 17:45
Room 1
Proffered papers 25: Upper GI
Karin Haustermans, Belgium;
Thomas Brunner, Austria
1770
Proffered papers
Clinical
17:15 - 17:25
Stereotactic body radiotherapy: neoadjuvant strategy of chemoradiation in pancreatic adenocarcinoma
M. Carmen Rubio Rodríguez, Spain
OC-0414

Abstract

Stereotactic body radiotherapy: neoadjuvant strategy of chemoradiation in pancreatic adenocarcinoma
Authors:

M. Carmen Rubio Rodríguez1, Xin Chen-Zhao2, Mercedes López1, Emilio Sánchez-Suagar1, Ovidio Hernando 1, Emilio Vicente3, Yolanda Quijano3, Hipólito Durán3, Susana Prados4, Susana Tabernero5, Antonio Cubillo6, Rafael Alvarez7, Irene Vázquez8, Maria Lourdes Orgáz9, Daniel Zucca10, Juan García Ruiz-Zorrila11, Angel Montero1, Raquel Ciérvide1, Jeanette Valero1, Mariola García-Aranda1, Beatriz Alvarez12, Rosa Alonso1, Mónica Núñez1, Miguel Angel de la Casa10, Pedro Fernández-Letón10

1Hospital Universitario HM Sanchinarro. HM Hospitales, Radiation Oncology, Madrid, Spain; 2Hospital Universitario HM Puerta del Sur. HM Hospitales , Radiation Oncology, Madrid, Spain; 3Hospital Universitario HM Sanchinarro. HM Hospitales, General and Gastrointestinal Surgery, Madrid, Spain; 4Hospital Universitario HM Sanchinarro. HM Hospitales , Gastroenterology, Madrid, Spain; 5Hospital Universitario HM Sanchinarro. HM Hospitales, Gastroenterology, Madrid, Spain; 6Hospital Universitario HM Sanchinarro. HM Hospitales , Medical Oncology, Madrid, Spain; 7Hospital Universitario HM Sanchinarro. HM Hospitales, Medical Oncology, Madrid, Spain; 8Universidad CEU San Pablo, Oncology, Madrid, Spain; 9Univesidad CEU San Pablo, Oncology, Madrid, Spain; 10Hospital Universitario HM Sanchinarro. HM Hospitales, Medical Physics, Madrid, Spain; 11Hospital Universitario HM Sanchinarro. HM Hospitales , Medical Physics, Madrid, Spain; 12Hospital Universitario HM Sanchinarro. HM Hospitales , Radiation Oncology, Madrid, Spain

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Purpose or Objective

Induction multiagent chemotherapy and intensification of radiation dose with SBRT has been studied as a neoadjuvant (NA) strategy for pancreatic adenocarcinoma (PA), in order to improve curative resection rates, pathological response, local control and survival.

Material and Methods

Patients with non-metastatic PA underwent SBRT as part of a NA strategy in a prospective observational study. CT-scan, 18-FDG-PET-CT, and endoscopic ultrasound(EU) were performed at diagnosis, before SBRT and surgery. Previous to SBRT, 2 intrapancreatic internal-fiducials were located guided-by EU in all patients. SBRT was delivered in 5 to 10 fractions, sequentially 3-4 weeks after induction chemotherapy. Surgery was performed at least 6 weeks after SBRT, in resectable patients, after restaging.




Results

Since February 2014 to December 2020, 80 patients (p), 34 male(42.5%) and 46 women(57.5%) were evaluated. Median age: 68 years(35-87). Tumor resectability groups at diagnosis were: resectable 20p(25%), borderline-resectable 32p(40%) and initially unresectable 28p(35%). Induction chemotherapy(CT): 57p(71.3%) nab-paclitaxel+gemcitabine, 14p(17.5%)   mFOLFIRINOX,  2p(2.5%), 5FU-based-CT, 1p(1.3%) NALIRINOX, 6p(7.55%), no induction or unknown-CT.

CTV was macroscopic tumour, pathological lymph nodes, and perivascular tissue if involved. PTV was CTV+5mm margin. Prescription dose to PTV and fractionation was adapted to tumor volume and constraints to organs at risk: 50Gy(5x10Gy) in 49p(61.3%), 62Gy(10x6.2Gy) in 8p(10%), 60Gy(10x6Gy) in 10p(12.5%), 50Gy(10x5Gy) in 12p(15%) and 40Gy(10x4Gy) in 1p(1.2%). BED10Gy was ≥90Gy in 67p(83.7%). IMRT/VMAT and daily IGRT was mandatory. Intrafraction control of pancreas motion was performed with respiratory control (ExacTrac-Adaptive-Gating or Active-Breathing- Coordinator systems).

After NA, 56p(72.5%) underwent surgery, 19 out of 28 were initially unresectable (67.9%). R0 resection was achieved in 53p(94.6%) and pN0 status in 39p(48.8%). Tumor regression grade(TRG) was: complete-or-marked response(TRG 0–1) in 26p(46.4%), moderate-response(TRG 2) in 24p(42.6%) and  poor-response(TRG 3) in 6p(10.7%). Patients with TRG 0-1 had a better OS (for TRG 2-3 was 22.2months (m), while for TRG 0-1 was not achieved). Median follow-up was 17.4m (3.0 –78.2m) since diagnosis. Actuarial median OS: 22.9m.  Actuarial OS at 12, 24 and 36m was 72.8%, 47.6% and 38.9% respectively. Cancer-specific OS was higher for surgical patients (p=0.001). Local progression free survival (L-PFS) was 97.4% at 12m and 86.2% at 24m. Median L-PFS was not achieved. For any kind of progression, the actuarial median PFS was 17.9m. At the time of the analysis 22p are still alive without disease. No grade ≥3 toxicity related to SBRT was observed.



Conclusion

Pancreatic SBRT is a feasible and well-tolerated treatment. Into a NA strategy, can improve tumour regression, R0 resections and local control rates. The benefit on OS will be evaluated with longer follow up.