Main Session
Sep 30
PQA 08 - Gastrointestinal Cancer, Nonmalignant Disease, Palliative Care

3506 - Bone Marrow-Sparing Radiotherapy could Limit or Avoid Radiation Induced Lymphopenia and Thrombocytopenia in Esophageal Cancer Patients after Neoadjuvant Chemoradiotherapy

02:30pm - 03:45pm PT
Hall F
Screen: 10
POSTER

Presenter(s)

Mathew Gorman, MD - Cross Cancer Institute, Edmonton, AB

K. Paskalice1, K. Trivedi1, A. Abraham1,2, J. Yun3,4, D. M. Severin2, K. Tankel1, K. Mulder5, and K. J. Joseph2,4; 1Cross Cancer Institute, Edmonton, AB, Canada, 2Division of Radiation Oncology, Cross Cancer Institute, Edmonton, AB, Canada, 3Division of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada, 4University of Alberta, Edmonton, AB, Canada, 5Division of Medical Oncology, Cross Cancer Institute, Edmonton, AB, Canada

Purpose/Objective(s):

Lymphopenia during chemoradiotherapy (CRT) is a strong predictor of poor outcomes in esophageal and gastro-esophageal junction cancer (OEGEJC). This study aims to identify dosimetric parameters predicting hematological toxicity (HT) in OEGEJC patients undergoing preoperative CRT. Additionally, it seeks to define bone marrow dose constraints to minimize or eliminate HT and hence improve survival outcomes.

Materials/Methods:

A retrospective analysis of 209 patients with OEGEJC referred for curative-intent preoperative CRT with CROSS protocol was conducted. Bone marrow volume (BMV) was delineated by contouring vertebrae spanning one level above and below the planning target volume (PTV). Dose-volume parameters were analyzed, and peripheral lymphocyte and platelet counts were recorded before and during treatment. The dose-volume relationship between BMV irradiated and hematologic toxicity was evaluated.

Results:

A statistically significant correlation was found between BMV irradiation, HT and overall survival (OS). Grade =2 lymphopenia was associated with V25 (p=0.043), V30 (p=0.045), and mean dose (p=0.021), while grade 4 thrombocytopenia correlated with V30 (p=0.029), V35 (p=0.046), and mean dose (p=0.004). Identified dose thresholds were Lymphopenia (Grade =2): V25 = 290.4 cc, V30 = 135 cc and thrombocytopenia (Grade 4): V30 = 60.9 cc, V35 = 39.15 cc. The BMV receiving =30 Gy (V30) was most strongly linked to HT. Increasing radiation doses to V5-V30 of BMV corresponded to statistically significant worse survival (p<0.05).

Conclusion:

This study demonstrates significant dose-volume relationship between BMV irradiated, HT and OS in patients with OEGEJC who received preoperative CRT with CROSS protocol. Restricting V30 to <135 cc for lymphopenia and <60.9 cc for thrombocytopenia may reduce HT and improve outcomes.