TY - JOUR
T1 - Estimating second malignancy risk in intensity-modulated radiotherapy and volumetric-modulated arc therapy using a mechanistic radiobiological model in radiotherapy for carcinoma of left breast
AU - Sakthivel, Vasanthan
AU - Kadirampatti Mani, Ganesh
AU - Mani, Sunil
AU - Boopathy, Raghavendiran
AU - Selvaraj, Jothybasu
N1 - Publisher Copyright:
© 2017 Journal of Medical Physics.
PY - 2017/10/1
Y1 - 2017/10/1
N2 - Objectives: The aim of this study is to estimate second cancer risk (SCR) in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) using a mechanistic radiobiological model. The model also takes into account patient age at exposure and the gender-specific correction factors of SCR. Materials and Methods: Fifty IMRT and VMAT plans were selected for the study. Monte Carlo-based dose calculation engine was used for dose calculation. Appropriate model parameters were taken from the literature for the mechanistic model to calculate excess absolute risk (EAR), lifetime attributable risk, integral dose and relative risk (RR) for lungs, contralateral breast, heart, and spinal cord. Results: The mean monitor unit (MU) in IMRT and VMAT plans were 751.1 ± 133.3 and 1004.8 ± 180, respectively, for IMRT and VMAT. The mean EAR values with age correction were 44.6 ± 11.9, 11.2 ± 6.4, 5.4 ± 4.0, 1.4 ± 0.5, and 0.3 ± 0.2 for left lung, right lung, contralateral breast, heart, and spinal cord, respectively, for the IMRT treatments and 54.6 ± 20.6, 30.2 ± 12.0, 13.8 ± 8.6, 1.6 ± 0.6, and 0.9 ± 0.5 for the VMAT treatments in units of 10,000 PY. The RR of 6.7% and 9.1%, respectively, for IMRT and VMAT found in our study using computational models is in close comparison with the value reported in a large epidemiological breast cancer study. Conclusions: VMAT plans had a higher risk of developing second malignancy in lung, contralateral breast, heart, and cord compared to IMRT plans. However, the increase in risk was found to be marginal compared to IMRT. Incorporating the age correction factor decreased the risk of contralateral breast SCR. No strong correlation was found between EAR and MU.
AB - Objectives: The aim of this study is to estimate second cancer risk (SCR) in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) using a mechanistic radiobiological model. The model also takes into account patient age at exposure and the gender-specific correction factors of SCR. Materials and Methods: Fifty IMRT and VMAT plans were selected for the study. Monte Carlo-based dose calculation engine was used for dose calculation. Appropriate model parameters were taken from the literature for the mechanistic model to calculate excess absolute risk (EAR), lifetime attributable risk, integral dose and relative risk (RR) for lungs, contralateral breast, heart, and spinal cord. Results: The mean monitor unit (MU) in IMRT and VMAT plans were 751.1 ± 133.3 and 1004.8 ± 180, respectively, for IMRT and VMAT. The mean EAR values with age correction were 44.6 ± 11.9, 11.2 ± 6.4, 5.4 ± 4.0, 1.4 ± 0.5, and 0.3 ± 0.2 for left lung, right lung, contralateral breast, heart, and spinal cord, respectively, for the IMRT treatments and 54.6 ± 20.6, 30.2 ± 12.0, 13.8 ± 8.6, 1.6 ± 0.6, and 0.9 ± 0.5 for the VMAT treatments in units of 10,000 PY. The RR of 6.7% and 9.1%, respectively, for IMRT and VMAT found in our study using computational models is in close comparison with the value reported in a large epidemiological breast cancer study. Conclusions: VMAT plans had a higher risk of developing second malignancy in lung, contralateral breast, heart, and cord compared to IMRT plans. However, the increase in risk was found to be marginal compared to IMRT. Incorporating the age correction factor decreased the risk of contralateral breast SCR. No strong correlation was found between EAR and MU.
KW - Excess absolute risk
KW - left breast
KW - lifetime attributable risk
KW - second cancer risk
KW - volumetric modulated arc therapy
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U2 - 10.4103/jmp.JMP_89_17
DO - 10.4103/jmp.JMP_89_17
M3 - Article
AN - SCOPUS:85038357441
SN - 0971-6203
VL - 42
SP - 234
EP - 240
JO - Journal of Medical Physics
JF - Journal of Medical Physics
IS - 4
ER -