Hypofractionated Radiotherapy Dose Scheme and Application of New Techniques Are Associated to a Lower Incidence of Radiation Pneumonitis in Breast Cancer Patients

Moon

et al. 2020

Preprint

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Background: Radiotherapy (RT) target volumes in breast cancer treatment increasingly include the internal mammary nodes, potentially increasing doses delivered to the heart and lung. The aim of this study was to compare cardiac and pulmonary doses in three-dimensional conformal radiotherapy (3DCRT), volumetric modulated arc therapy (VMAT), and proton beam therapy (PBT) with and without continuous positive airway pressure (CPAP), delivered in conventional fractionation (CF) or in hypofractionated (HF) schedules.Methods: In a dataset of 15 patients with left-sided breast cancer, partial wide tangential 3DCRT delivered in CF (50/25) and in HF (40/15) schedules as well as PBT delivered in CF and two-partial arc VMAT delivered in a HF schedule, each under CPAP and free breathing (FB) conditions were extensively examined. Target volume coverage and doses to organs-at-risk (OARs) were calculated for each technique. Outcomes were compared with one-way analysis of variance and the Bonferroni test, with P-values <0.05 considered significant. Results: Target volume coverage was within acceptable levels in all interventions, except for internal mammary lymph nodes D90 (99% in PBT, 90% in VMAT-CPAP, 84% in VMAT-FB, and 74% in 3DCRT). Mean heart dose (MHD) was the lowest and highest in PBT (<1 Gy) and 3DCRT with CF/FB (7.8 Gy), respectively. In photon-based techniques, the use of VMAT in HF schedules with CPAP resulted in an MHD of 2.2 Gy. Lung V20 and mean lung dose (MLD) were the highest in 3DCRT-CF-FB (44% and 20 Gy, respectively) and lowest in both VMAT-HF-CPAP and PBT (7–9% and approximately 5–6 Gy, respectively). VMAT-HF-CPAP and PBT delivered a comparable maximum dose to the left ascending artery (7.2 Gy and 6.70 Gy, respectively, with the highest dose delivered by 3DCRT [47.6 Gy]). The average doses to the contralateral breast were 0.004, 1, and 2.1 Gy in PBT, 3DCRT, and VMAT, respectively.Conclusions: PBT delivered the lowest doses to most OARs in RT for left-sided breast cancer with regional nodal irradiation. However, the dosimetric gap between proton and photon RT has narrowed substantially with modern techniques such as VMAT and CPAP; the clinical relevance of these differences is yet to be elucidated.

Section: Discussionsupporting

confidence: 91%

Dosimetric Comparison of Radiation Techniques for Comprehensive Regional Nodal Radiation Therapy for Left-Sided Breast Cancer: A Treatment Planning Study

Moon

et al. 2020

Preprint

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“…The maximum LAD dose showed a significant reduction of 9.3 Gy and 8.4 Gy with an HF schedule in FB and CPAP conditions, respectively; this finding is similar to that reported by Pierre et al (13). In addition, the 40/15 HF schedule can help reduce the lung dose to a greater extent than the 50/25 schedule, a result consistent with that of a previous study (28). However, the clinical relevance of these dosimetric differences associated with HF regimens is yet to be elucidated.…”

Section: Vmat With Cpap In Hf: An Encouraging Choicesupporting

confidence: 91%

Dosimetric Comparison of Radiation Techniques for Comprehensive Regional Nodal Radiation Therapy for Left-Sided Breast Cancer: A Treatment Planning Study

Moon

et al. 2021

Front. Oncol.

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PurposeHow modern cardiac sparing techniques and beam delivery systems using advanced x-ray and proton beam therapy (PBT) can reduce incidental radiation exposure doses to cardiac and pulmonary organs individually or in any combination is poorly investigated.MethodsAmong 15 patients with left-sided breast cancer, partial wide tangential 3D-conformal radiotherapy (3DCRT) delivered in conventional fractionation (CF) or hypofractionated (HF) schedules; PBT delivered in a CF schedule; and volumetric modulated arc therapy (VMAT) delivered in an HF schedule, each under continuous positive airway pressure (CPAP) and free-breathing (FB) conditions, were examined. Target volume coverage and doses to organs-at-risk (OARs) were calculated for each technique. Outcomes were compared with one-way analysis of variance and the Bonferroni test, with p-values <0.05 considered significant.ResultsTarget volume coverage was within acceptable levels in all interventions, except for the internal mammary lymph node D95 (99% in PBT, 90% in VMAT-CPAP, 84% in VMAT-FB, and 74% in 3DCRT). The mean heart dose (MHD) was the lowest in PBT (<1 Gy) and VMAT-CPAP (2.2 Gy) and the highest in 3DCRT with CF/FB (7.8 Gy), respectively. The mean lung dose (MLD) was the highest in 3DCRT-CF-FB (20 Gy) and the lowest in both VMAT-HF-CPAP and PBT (approximately 5–6 Gy). VMAT-HF-CPAP and PBT delivered a comparable maximum dose to the left ascending artery (7.2 and 6.13 Gy, respectively).ConclusionsBoth proton and VMAT in combination with CPAP can minimize the radiation exposure to heart and lung with optimal target coverage in regional RT for left-sided breast cancer. The clinical relevance of these differences is yet to be elucidated. Continued efforts are needed to minimize radiation exposures during RT treatment to maximize its therapeutic index.

“…Our previous study showed that VMAT influenced RP; ipsilateral lung V 30 Gy > 10% was associated with RP (HR 2.89) and VMAT remained significant for determining the lung V 30 Gy (OR 0.12) 9 . VMAT was also able to reduce the mean lung dose and lung volume exposed to 5 to 40 Gy in patients treated with internal mammary irradiation to a greater extent than 3D‐RT with deep‐inspiration breath‐holding 9 . Significant differences were observed between HF‐3D and HF‐VMAT considering the ipsilateral lung dose in the current random samples.…”

Section: Discussionmentioning

confidence: 93%

“…All patients underwent simulation computed tomography (CT) for RT planning. Techniques for immobilization differed based on the institutional protocol 9 …”

Section: Methodsmentioning

confidence: 99%

Hypofractionated volumetric‐modulated arc therapy for breast cancer: A propensity‐score‐weighted comparison of radiation‐related toxicity

Kim

Shah

et al. 2021

Intl Journal of Cancer

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We assessed the clinical benefit of combining volumetric‐modulated arc therapy (VMAT) and hypofractionated radiotherapy (HF‐RT) considering the incidence of radiation‐related toxicities. After a retrospective review for breast cancer patients treated with adjuvant RT between 2005 and 2017, a total of 4209 patients treated with three‐dimensional conventional fractionation (CF‐3D, 50.4 Gy/28 fractions) and 1540 patients treated with HF‐RT (768 received HF‐3D; 772, HF‐VMAT; 40 Gy/15 fractions) were included. A total of 2229 patients (38.8%) received regional node irradiation (RNI): 1642 (39.0%), 167 (21.7%) and 420 (54.4%) received RNI via CF‐3D, HF‐3D and HF‐VMAT, respectively. Acute/subacute and late toxicities were evaluated. Propensity scores were calculated via logistic regression. Grade 2+ acute/subacute toxicities was the highest in CF‐3D group (15.0%, 2.6% and 1.6% in CF‐3D, HF‐3D and HF‐VMAT, respectively; P < .001). HF‐VMAT reduced Grade 2+ acute/subacute toxicities significantly compared to CF‐3D (odds ratio [OR] 0.11, P < .001) and HF‐3D (OR 0.45, P = .010). The 3‐year cumulative rate of late toxicities was 18.0% (20.1%, 10.9% and 13.4% in CF‐3D, HF‐3D and HF‐VMAT, respectively; P < .001). On sensitivity analysis, the benefit of HF‐VMAT was high in the RNI group. Acute and late toxicities were fewer after HF‐VMAT than after HF‐3D or CF‐3D, especially in women who underwent RNI.