Hypofractionated Radiotherapy With Simultaneous-integrated Boost After Breast-conserving Surgery Compared to Standard Boost-applications Using Helical Tomotherapy With TomoEdge

Abstract

Background/Aim: This comparative plan study examines a range of boost-radiation methods in adjuvant radiotherapy of breast cancer using helical intensity-modulated radiotherapy with TomoEdge-technique. Impact of hypofractionated radiation with simultaneous-integrated boost (SIB) and influence of differing assumed α/β-values were examined. Patients and Methods: For 10 patients with left-sided breast cancer each four helical IMRT-plans with TomoEdge-technique were created: hypofractionated+SIB (H-SIB) (42.4/54.4 Gy, 16 fractions), normofractionated+SIB (N-SIB) (50.4/64.4 Gy, 28 fractions), hypofractionated+sequential-boost (H-SB) (42.4 Gy/16 fractions+16 Gy/ 8 fractions), normofractionated+ sequential-boost (N-SB) (50.4 Gy/ 28 fractions+16 Gy/ 8 fractions). Equivalent doses (EQD 2 ) to organs-at-risk (OAR) and irradiated mammary-gland were analysed for different assumed α/β-values. Results: The mean EQD 2 to OAR was significantly lower using hypofractionated radiation-techniques. H-SIB and H-SB were not significantly different. H-SIB and N-SIB conformed significantly better to the breast planning-target volume (PTV) and boost-volume (BV) than H-SB and N-SB. Regarding BV, mean EQD 2 was significantly higher for all α/β-values investigated when using H-SIB and N-SIB. Regarding PTV, there were no clinically relevant differences. Conclusion: Relating to dosimetry, H-SIB is effective compared to standard-boost-techniques.Globally, breast cancer is the most common form of cancer in women (1). Surgery and adjuvant radiation therapy are the central pillars of curative therapy when treating localised breast cancer. Screening programs enable tumours to be discovered earlier, meaning that breast-conserving surgery alongside adjuvant radiotherapy achieves high cure rates. Additional radiotherapy significantly increases local control and prolongs overall survival (2, 3). As part of adjuvant radiation therapy, a radiation boost to the tumour bed results in significantly improved local control rates in the case of risk factor constellations, such as T2 tumours, positive lymph nodes, premenopausal patients, poorly differentiated G3 tumours, human-epidermal-growth-factor-receptor2 (HER2/ neu) positivity, and narrow resection margins (4, 5). The radiation boost can be applied in several ways: teletherapy using photons or electrons, intra-operative radiotherapy, or interstitial brachytherapy (6-9). Thus far, the radiation boost is generally delivered sequentially, i.e., once whole breast radiation therapy is complete. Simultaneous integrated boost (SIB) radiation therapy is a recent approach to delivering radiation boosts (6). SIB can be administered using different percutaneous photon therapy radiation techniques, including 3D conformal radiation therapy (3D-CRT) and intensitymodulated radiation therapy (IMRT).Step-and-shoot IMRT and rotational IMRT, also known as volumetric arc therapy (VMAT), are commonly reported in the literature (6, 10, 11). The advantages of SIB in comparison to sequential boost (SB) include the reduced total ...

Comparison of Heart and Lung Doses According to Tumor Bed Boost Techniques in Early-Stage Left-Sided Breast Cancer: Simultaneous Integrated Boost versus Sequential Boost

“…SIB allows the simultaneous delivery of a differential dose per fraction to different target volumes and offers several advantages such as a higher biologically effective dose to PTV TB , shorter overall treatment time than SEQ, and highly homogeneous and conformal dose distributions compared with SEQ or field-in-field techniques [ 20 , 21 ]. Several recent studies have examined intensity-modulated radiation therapy (IMRT) with SIB plans and have shown dosimetric advantages [ 5 , 7 ].…”

Hypofractionation with simultaneous integrated boost after breast-conserving surgery: Long term results of two phase-II trials

“…Furthermore, toxicity rates were favorable in our analysis and in line with previously published findings. Dosimetric studies show improved dose homogeneity with SIB which may impact the risk of late normal tissue effects, especially outside of the boost area [ 29 ]. Despite the increased single dose in the tumor bed with SIB, there are no signs of an increased risk of local fibrosis.…”

Hypofractionated whole breast irradiation with simultaneous integrated boost in breast cancer using helical tomotherapy with or without regional nodal irradiation: A report of acute toxicities

“…A phase II study using Volumetric Modulated Radiation Therapy (VMAT) for hypofractionated whole breast irradiation with simultaneous integrated boost (HF-WBI-SIB) confirmed the safety and reported good cosmetic results, even in patients who received adjuvant systemic therapy (5,6). The latest comparative dosimetric study (7), demonstrated that HF-WBI-SIB using HT with TomoEdge offered a significantly lower mean equivalent dose in 2-Gy fractions (EQD2) to OARs and showed no significant difference between HF-SIB and sequential boost. Both HF-SIB and normally fractionated SIB (N-SIB) conformed significantly better to the breast and boost planning target volumes (PTV) than both sequential boost techniques.…”