Secondary Cancer Risks Associate with High Technology Radiotherapy for Ovarian Ablation
Abstract
Purpose
To evaluate the organ equivalent dose (OED) and the excess absolute risk (EAR) of radiation-induced secondary cancers associated with ovarian ablation, a treatment performed for a benign condition, using different radiotherapy techniques and biological dose–response models.
Methods
Differential dose–volume histogram (DVH) data from 15 patients undergoing ovarian ablation were analyzed. Six pelvic organs at risk were evaluated: bladder, rectum, colon, uterus, bone, and soft tissue. Four radiotherapy techniques were considered: two-dimensional radiotherapy (2DRT), three-dimensional conformal radiotherapy (3DRT), intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT). OED was calculated using different biological dose–response models (mechanistic, bell-shaped, and plateau), and the resulting values were used to estimate the excess absolute risk (EAR) for radiation-induced carcinoma and sarcoma. Descriptive and comparative analyses were performed to assess trends among techniques and interpatient variability.
Results
Although absolute OED values differed among the biological models, consistent trends were observed when comparing the same organ across treatment techniques. For organs adjacent to the target volume, such as the rectum, colon, and uterus, modulated techniques generally resulted in lower median OED and EAR values compared to 2DRT. In contrast, lower risk values for the bladder were observed with 2DRT, likely due to reduced target dose conformity. For bone and soft tissue, higher EAR values were associated with modulated techniques, which may be attributed to the increased exposure of larger tissue volumes to low radiation doses, a known characteristic of modern highly conformal techniques.
Conclusion
Although ovarian ablation is performed for a benign condition, the results demonstrate that radiotherapy technique selection significantly influences the estimated risk of secondary cancer induction. Therefore, quantitative radiobiological risk assessment is essential to support clinical decision-making, particularly in scenarios where radiotherapy remains a viable and accessible treatment option.