Keywords:
Genital / Reproductive system female, Oncology, CT-Quantitative, Radiation therapy / Oncology, Demineralisation-Bone, Toxicity
Authors:
C. Godber, C. Clark, T. Diamond, R. Rahbari
DOI:
10.26044/ranzcr2023/C-154
Methods and materials
This retrospective study was completed as a file review of patients who underwent treatment for gynaecological malignancies at a single metropolitan hospital from 2020-2023. For inclusion in the study, patients needed to have a gynaecological malignancy being treated with curative intent, received external beam radiotherapy to the pelvis (+/- Para-Aortic region), ECOG 0-2, and have a recorded baseline Quantitative Computed Tomography (QCT) BMD scan prior to treatment with a repeat scan within 18 months post treatment. Exclusion criteria were patients receiving with palliative intent radiotherapy, evidence of disease including chronic renal disease or a diagnosis of metabolic bone disease or the long-term use of anti-osteoporotic therapies, the absence of a baseline QCT or follow-up QCT not performed within the designated time interval.
Patient demographics, diagnosis, concurrent chemotherapy regimens, surgical history and relevant comorbidities were recorded. Treatment plans were reviewed to record treatment prescription, radiotherapy dose, superior border of the radiotherapy field and mean dose to the third lumbar vertebrae and left femoral head. Baseline and post treatment QCTs were evaluated at the lumbar spine and the left femoral neck. The precision error for lumbar spine (L1-L4) is 1% and for the femoral neck 1.5%.
The primary outcome was percentage change in BMD at the lumbar spine and left femoral neck. Lumbar spine BMD loss was compared for two groups defined by the upper border of the treatment field (pelvis only vs pelvis + para-aortic nodes). Left femoral head and L3 mean dose were compared with left femoral neck and L3 BMD loss to investigate the effect of radiotherapy dose on bone loss.