Risk of contralateral breast and ipsilateral lung cancer induction from forward-planned IMRT for breast carcinoma. (April 2019)

• Record Type: Journal Article
• Authors: Mazonakis, M.; Stratakis, J.; Lyraraki, E.; Damilakis, J.
• Is Part Of: Physica medica. Volume 60(2019)
• Page Start: 44
• Page End: 49
• Publication Date: 2019-04
• Subjects: Radiation therapy -- Breast cancer -- Secondary malignancies; Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2019.03.021
• Languages: English
• ISSNs: 1120-1797

Abstract

Highlights: Second cancer risks were assessed using patient-specific data and a mechanistic model. fIMRT for breast cancer increases the cancer risks compared to baseline probabilities. Hypofractionated instead of standard fractionated IMRT leads to a reduced cancer risk. Abstract: Purpose: To assess the risk of contralateral breast and ipsilateral lung cancer induction from forward-planned IMRT for breast carcinoma. Methods: The study group included 13 females irradiated for breast cancer with 6 MV photons. The plans were initially generated by using standard fractionated (SF) forward-planned IMRT (50 Gy at 2 Gy/fraction). Hypofractionated (HF) IMRT (42.56 Gy at 2.66 Gy/fraction) was also employed for plan creation. Differential DVHs derived from the treatment plans were used to estimate the patient-specific organ equivalent dose (OED) to the contralateral breast and ipsilateral lung and the relevant lifetime attributable risks of cancer development. These estimates were made with a non-linear mechanistic model. The radiotherapy-induced cancer risks were combined with the lifetime intrinsic risk (LIR) values for unexposed people to determine the patient- and organ-specific relative risk (RR) for second cancer induction. Results: The OED of the contralateral breast from SF and HF forward-planned IMRT was up to 0.99 and 0.86 Gy, respectively. The corresponding values for the ipislateral lung were 4.15 and 3.66 Gy. The patient-specific RR range for the contralateral breast and ipislateral lung cancer induction following SF forward-planned IMRT was 1.04–1.10 and 1.60–1.81, respectively. The corresponding RRs from hypofractionated treatment were 1.03–1.09 and 1.53–1.73. Conclusions: The treatment of primary breast carcinoma with the use of SF or HF forward-planned IMRT results in increased probabilities for developing secondary malignancies in the healthy contralateral breast or ipsilateral lung compared to the respective LIRs for an unexposed population.