Publication: Secondary cancer risk from modern external-beam radiotherapy of prostate cancer patients: Impact of fractionation and dose distribution
Issued Date
2021-07-01
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ISSN
13499157
04493060
04493060
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2-s2.0-85112124764
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Mahidol University
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SCOPUS
Bibliographic Citation
Journal of Radiation Research. Vol.62, No.4 (2021), 707-717
Suggested Citation
Chomporn Sitathanee, Puangpen Tangboonduangjit, Mantana Dhanachai, Sawanee Suntiwong, Pornpan Yongvithisatid, Sukanya Rutchantuk, Pimolpun Changkaew, Rattana Watjiranon, Suphalak Khachonkham, Vipa Boonkitticharoen Secondary cancer risk from modern external-beam radiotherapy of prostate cancer patients: Impact of fractionation and dose distribution. Journal of Radiation Research. Vol.62, No.4 (2021), 707-717. doi:10.1093/jrr/rrab038 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/77031
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Title
Secondary cancer risk from modern external-beam radiotherapy of prostate cancer patients: Impact of fractionation and dose distribution
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Abstract
Modern radiotherapy (RT) uses altered fractionation, long beam-on time and image-guided procedure. This study aimed to compare secondary cancer risk (SCR) associated with primary field, scatter/leakage radiations and image-guided procedure in prostate treatment using intensity-modulated RT (IMRT), CyberKnife stereotactic body RT (CK-SBRT) in relative to 3-dimensional conformal RT (3D-CRT). Prostate plans were generated for 3D-CRT, IMRT (39 fractions of 2 Gy), and CK-SBRT (five fractions of 7.25 Gy). Excess absolute risk (EAR) was calculated for organs in the primary field using Schneider's mechanistic model and concept of organ equivalent dose (OED) to account for dose inhomogeneity. Doses from image-guided procedure and scatter/leakage radiations were determined by phantom measurements. The results showed that hypofractionation relative to conventional fractionation yielded lower SCR for organs in primary field (p ≤ 0.0001). SCR was further modulated by dose-volume distribution. For organs near the field edge, like the rectum and pelvic bone, CK-SBRT plan rendered better risk profiles than IMRT and 3D-CRT because of the absence of volume peak in high dose region (relative risk [RR]: 0.65, 0.22, respectively, p ≤ 0.0004). CK-SBRT and IMRT generated more scatter/leakage and imaging doses than 3D-CRT (p ≤ 0.0002). But primary field was the major contributor to SCR. EAR estimates (risk contributions, primary field: Scatter/leakage radiations: Imaging procedure) were 7.1 excess cases per 104 person-year (PY; 3.64:2.25:1) for CK-SBRT, 9.93 (7.32:2.33:1) for IMRT and 8.24 (15.99:2.35:1) for 3D-CRT (p ≤ 0.0002). We conclude that modern RT added more but small SCR from scatter/leakage and imaging doses. The primary field is a major contributor of risk which can be mitigated by the use of hypofractionation.
