Comparison of Breast Cancer Radiotherapy Techniques Regarding Secondary Cancer Risk and Normal Tissue Complication Probability – Modelling and Measurements Using a 3D-Printed Phantom

Abstract

BackgroundRadiotherapy after breast-conserving therapy is a standard postoperative treatment of breast cancer, which can be carried out with a variety of irradiation techniques. The treatment planning must take into consideration detrimental effects on the neighbouring organs at risk—the lung, the heart, and the contralateral breast, which can include both short- and long-term effects represented by the normal tissue complication probability and secondary cancer risk.Patients and MethodsIn this planning study, we investigate intensity-modulated (IMRT) and three-dimensional conformal (3D-CRT) radiotherapy techniques including sequential or simultaneously integrated boosts as well as interstitial multicatheter brachytherapy boost techniques of 38 patients with breast-conserving surgery retrospectively. We furthermore develop a 3D-printed breast phantom add-on to allow for catheter placement and to measure the out-of-field dose using thermoluminescent dosimeters placed inside an anthropomorphic phantom. Finally, we estimate normal tissue complication probabilities using the Lyman–Kutcher–Burman model and secondary cancer risks using the linear non-threshold model (out-of-field) and the model by Schneider et al. (in-field).ResultsThe results depend on the combination of primary whole-breast irradiation and boost technique. The normal tissue complication probabilities for various endpoints are of the following order: 1%–2% (symptomatic pneumonitis, ipsilateral lung), 2%–3% (symptomatic pneumonitis, whole lung), and 1%–2% (radiation pneumonitis grade ≥ 2, whole lung). The additional relative risk of ischemic heart disease ranges from +25% to +35%. In-field secondary cancer risk of the ipsilateral lung in left-sided treatment is around 50 per 10,000 person-years for 20 years after exposure at age 55. Out-of-field estimation of secondary cancer risk results in approximately 5 per 10,000 person-years each for the contralateral lung and breast.ConclusionsIn general, 3D-CRT shows the best risk reduction in contrast to IMRT. Regarding the boost concepts, brachytherapy is the most effective method in order to minimise normal tissue complication probability and secondary cancer risk compared to teletherapy boost concepts. Hence, the 3D-CRT technique in combination with an interstitial multicatheter brachytherapy boost is most suitable in terms of risk avoidance for treating breast cancer with techniques including boost concepts.

Incidence of Nonkeratinocyte Skin Cancer After Breast Cancer Radiation Therapy

“…There is also a risk of recurrence from the breast cancer metastasizing to another part of the body or increased susceptibility to a second primary cancer in a new location . Although subsequent cancers may arise due to chance, there is well-established evidence that certain types of breast cancer treatments, such as radiation therapy, result in an increased risk of secondary cancer and damage to surrounding tissues …”

“…6,7 Although subsequent cancers may arise due to chance, there is well-established evidence that certain types of breast cancer treatments, such as radiation therapy, result in an increased risk of secondary cancer and damage to surrounding tissues. [8][9][10] The role of radiation therapy in subsequent cancer development has been studied for a range of primary cancers, including those of the prostate and rectum, 11 head and neck, 12 and breast. 13 Much of the literature focuses on secondary lung cancer or cardiovascular disease risk after breast cancer radiation therapy.…”

“… 6 , 7 Although subsequent cancers may arise due to chance, there is well-established evidence that certain types of breast cancer treatments, such as radiation therapy, result in an increased risk of secondary cancer and damage to surrounding tissues. 8 , 9 , 10 …”

Proton Therapy in Breast Cancer: A Review of Potential Approaches for Patient Selection

“…To be noted, there are few existing NTCP models tailored for BC radiotherapy, and generally, they are obtained from photon therapy cohorts, 42 – 44 which brings up questions about the applicability of photon NTCP models to PT. Blanchard et al verified that in patients with head and neck cancer (HNC), the accuracy of NTCP model based on photon therapy data decreased in PT, but the diversity was within the acceptable range.…”

Calculation of Organ Dose Distribution (in-field and Out-of-field) in Breast Cancer Radiotherapy on RANDO Phantom Using GEANT4 Application for Tomographic Emission (Gate) Monte Carlo Simulation

“…[ 12 18 19 20 21 22 ] Several authors have measured doses of in-field and out-of-field organs in physical phantoms with passive detectors and compared their results with the TPS results. [ 8 12 21 22 23 24 25 ] All the investigators reported that the TPS cannot calculate the out-of-field dose accurately and the gold standard method to estimate this dose is MC simulation based on a patient’s DICOM data or using computational phantom. [ 12 17 26 27 28 29 ] Bednarz et al .,[ 26 ] Joosten et al .,[ 16 ] Berris et al .,[ 27 ] and Wang and Ding (2014)[ 30 ] evaluated the out-of-field dose calculated by different TPS and used the MC simulation to estimate the uncertainties of calculated organ doses.…”