ESTRO 2022

Session Item

Urology

Session Code: 6018

Session Type: Poster (digital)

Track: Clinical

Hematological toxicity in pN1 prostate cancer patients treated with extended field irradiation

Charlien Berghen, Belgium

Presentation Number: PO-1406

Abstract

Abstract Title:

Hematological toxicity in pN1 prostate cancer patients treated with extended field irradiation

Authors:

Charlien Berghen¹, Annouschka Laenen², Robin De Roover³, Daan Dierickx⁴, Steven Joniau⁵, Kato Rans¹, Wouter Crijns¹, Evert Baten⁶, Herlinde Dumez⁷, Wouter Everaerts⁵, Gert De Meerleer¹

¹University Hospitals Leuven, Department of Radiation Oncology, Leuven, Belgium; ² Interuniversity Institute for Biostatistics Leuven, Department of Public Health & Primary Care, Leuven, Belgium; ³University Hospitals of Leuven, Department of Radiation Oncology, Leuven, Belgium; ⁴University Hospitals Leuven, Department of Hematology, Leuven, Belgium; ⁵University Hospitals Leuven, Department of Urology, Leuven, Belgium; ⁶General Regional Hospital Tienen, Department of Urology, Tienen, Belgium; ⁷University Hospitals Leuven, Department of General Medical Oncology, University Hospitals Leuven, Leuven Cancer Institute, and Laboratory of experimental Oncology, Department of Oncology, Catholic University Leuven, Leuven, Belgium

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Purpose or Objective

Adding whole pelvic radiotherapy (WPRT) to androgen deprivation therapy improves survival in patients diagnosed with pN1 prostate cancer (PCa). Enlarged treatment field with elective irradiation of the retroperitoneal lymph nodes may further improve outcome, as many of those patients already harbour micro metastases in the retroperitoneal lymph nodes. However, a larger irradiated volume of bone marrow (BM) can increase hematologic toxicity (HemT).

Material and Methods

We evaluated the effect of WPRT and retroperitoneal RT on hematological toxicity in patients treated for pN1 PCa in the PART trial (NCT03079323), a prospective phase 2 single-arm trial, and searched for predictive dose-volume effects for BM. Blood counts were depicted in time evolution of delta levels, and time to recovery with respect to baseline. HemT was graded according to the CTCAE v4.0. BM was delineated as lumbosacral spine (LSS), iliac crests (IC), lower pelvis (LP), whole pelvis (WP), retroperitoneal (RP) and combined WP+RP (ALL), and the relative dose-volume histograms were calculated.

Results

The first 50 patients of the PART study were included in this trial. HemT was very acceptable, with no G3 or higher toxicity except for absolute lymphocyte count (ALC). Acute and late G3 ALC was present in 49% and 16% of the patients, respectively. More than 50% of the patients had full hematological recovery at the last time of follow-up, except for white blood cell count (WBC) and lymphocytes. BM volume LSS V50 Gy was significantly correlated with late % lymphocytes decline, and IC V50 Gy was correlated with both acute and late decline of ALC. None of the dose on the BM volumes was significantly associated with the time to recovery.

Conclusion

This is the first trial reporting on HemT and dose-volume effects for BM caused by extended-field radiotherapy in chemo-naive patients. General toxicity appeared to be low, except for decline in ALC.