Secondary cancer risk after Whole-breast radiation therapy: Field-in-Field versus Intensity-Modulated radiation therapy versus Volumetric-Modulated arc therapy.

Abstract

OBJECTIVE\nIn this study, we used the concept of organ-equivalent dose (OED) to evaluate the excess absolute risk (EAR) for secondary cancer in various organs after radiation treatment for breast cancer.\n\n\nMETHODS\nUsing computed tomography (CT) data set of 12 patients, we generated three different whole-breast radiation treatment plans using 50\u2009Gy in 2\u2009Gy fractions: three-dimensional conformal radiotherapy (3D-CRT) with a field-in-field (FinF) technique, intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT). The OEDs were calculated from differential dose-volume histograms (dDVHs) on the basis of the linear-exponential, plateau, and full mechanistic dose-response models. Secondary cancer risks of the contralateral breast (CB), contralateral lung (CL), and ipsilateral lung (IL) were estimated and compared.\n\n\nRESULTS\nThe lowest EARs for the CB, CL, and IL were achieved with FinF, which reduced the EARs by 77%, 88%, and 56% relative to those with IMRT, and by 77%, 84%, and 58% relative to those with VMAT, respectively. The secondary cancer risk for FinF was significantly lower than those of IMRT and VMAT. OED-based secondary cancer risks for CB and IL were similar when IMRT and VMAT were used, but the risk for CL was statistically lower when VMAT was used.\n\n\nCONCLUSION\nThe overall estimation of EAR indicated that the radiation-induced cancer risk of breast radiation therapy was lower with FinF than with IMRT and VMAT. Therefore, when secondary cancer risk is a major concern, FinF is considered to be the preferred treatment option in irradiation of whole-breast.\n\n\nADVANCES IN KNOWLEDGE\nSecondary malignancy estimation after breast radiotherapy is becoming an important subject for comparative treatment planning.When secondary cancer risk a major concern, FinF technique is considered the preferred treatment option in whole breast patients.