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Purpose: Our purpose was to investigate the interfraction and intrafraction reproducibility and practical applicability of continuous positive airway pressure (CPAP) for left breast volumetric modulated arc therapy (VMAT)., Methods and Materials: Interfraction reproducibility of the position of the heart was evaluated by measuring the heart-to-target distance on 20 planning computed tomography (CT) and 300 daily cone beam CT of 20 patients with left breast cancer treated with a 15-fraction VMAT. The dosimetric metrics of the whole heart and its substructures were compared between CPAP and free-breathing based VMAT plans. Intrafraction reproducibility was evaluated by measuring the motions of the breast target and diaphragm in 4-dimensional CT of 20 female patients with nonbreast cancer. Lastly, we analyzed the CPAP compliance data of 237 consecutive patients with left-sided breast cancer with and without internal mammary node irradiation (IMNI)., Results: The heart position was reproducible as evidenced by an absolute average heart-to-target distance error of 2.0 ± 2.0 mm. Compared with free-breathing, CPAP significantly reduced the mean heart dose and the dose to the left ventricle and left anterior descending artery. The average intrafraction position variation of the breast target was 0.5 ± 0.5, 2.5 ± 2.0, and 1.8 ± 1.4 mm in the mediolateral, craniocaudal, and anteroposterior directions, respectively. CPAP was successfully applied in 221 patients (93%), with a mean heart dose of 1.6 ± 0.7 Gy (IMNI: 2.0 Gy and no IMNI: 1.1 Gy)., Conclusions: CPAP has adequate heart-sparing capability and sufficient reproducibility in VMAT for left-sided breast cancer treatment, with a high compliance rate. Thus, CPAP is applicable in routine practice for left-sided breast cancer radiation therapy., (Copyright © 2022 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Background: Adjuvant radiation therapy improves the overall survival and loco-regional control in patients with breast cancer. However, radiation-induced heart disease, which occurs after treatment from incidental radiation exposure to the cardiac organ, is an emerging challenge. This study aimed to generate synthetic contrast-enhanced computed tomography (SCECT) from non-contrast CT (NCT) using deep learning (DL) and investigate its role in contouring cardiac substructures. We also aimed to determine its applicability for a retrospective study on the substructure volume-dose relationship for predicting radiation-induced heart disease., Methods: We prepared NCT-CECT cardiac scan pairs of 59 patients. Of these, 35, 4, and 20 pairs were used for training, validation, and testing, respectively. We adopted conditional generative adversarial network as a framework to generate SCECT. SCECT was validated in the following three stages: (1) The similarity between SCECT and CECT was evaluated; (2) Manual contouring was performed on SCECT and CECT with sufficient intervals and based on this, the geometric similarity of cardiac substructures was measured between them; (3) The treatment plan was quantitatively analyzed based on the contours of SCECT and CECT., Results: While the mean values (± standard deviation) of the mean absolute error, peak signal-to-noise ratio, and structural similarity index measure between SCECT and CECT were 20.66 ± 5.29, 21.57 ± 1.85, and 0.77 ± 0.06, those were 23.95 ± 6.98, 20.67 ± 2.34, and 0.76 ± 0.07 between NCT and CECT, respectively. The Dice similarity coefficients and mean surface distance between the contours of SCECT and CECT were 0.81 ± 0.06 and 2.44 ± 0.72, respectively. The dosimetry analysis displayed error rates of 0.13 ± 0.27 Gy and 0.71 ± 1.34% for the mean heart dose and V5Gy, respectively., Conclusion: Our findings displayed the feasibility of SCECT generation from NCT and its potential for cardiac substructure delineation in patients who underwent breast radiation therapy., (© 2022. The Author(s).)

Purpose: Although lapatinib-induced hepatotoxicity can cause severe clinical complications in patients, the factors affecting hepatotoxicity have rarely been investigated. The purpose of this study was to investigate risk factors for hepatotoxicity and time to lapatinib-induced hepatotoxicity., Methods: This retrospective study was performed on metastatic breast cancer patients treated with lapatinib. Various factors were evaluated for hepatotoxicity and time to hepatotoxicity, including sex, age, body weight, height, body surface area, underlying disease, smoking history, start dose of lapatinib, status of liver metastasis, and concomitant drugs., Results: Among 159 patients, the percentage of patients with hepatotoxicity after lapatinib initiation was 57.9% (n = 92). Multivariate analysis showed that concomitant use of H2 blockers increased the incidence of hepatotoxicity by 2.3-fold. Patients who received CYP3A4 inducers had 3.1 times higher risk of hepatotoxicity incidence; the attributable risks of H2 blockers and CYP3A4 inducers were 56.7% and 68.1%, respectively. Use of H2 blockers increased the hazard of time to hepatotoxicity by 1.8-fold compared to non-use of H2 blockers., Conclusions: Our study demonstrated that concomitant use of H2 blockers and CYP3A4 inducers was associated with lapatinib-induced hepatotoxicity. Close liver function monitoring is recommended, especially in patients receiving H2 blockers or CYP3A4 inducers.

Trastuzumab is a drug used for the treatment of metastatic breast cancer patients. Due to blockage of the human epidermal growth factor receptor 2 signaling in cardiac myocytes, cardiotoxicity has been observed. There are many studies that investigated risk factors for trastuzumab-induced cardiotoxicity, but no study has been published for factors on the time to cardiotoxicity. This study aimed to investigate the factors for the time to occur trastuzumab-induced cardiotoxicity. From January 2014 to December 2015, a retrospective study was performed with breast cancer patients who were treated with trastuzumab. Associations between presence of and time to cardiotoxicity and various factors were analyzed. Based on multivariate models, it was found that baseline left ventricular ejection fraction (LVEF) < 62.5% (AHR 5.96, 95% CI 2543-13.95) and anthracycline-based chemotherapy (AHR 7.90, 95% CI 1.05-59.71) were significant factors for time to cardiotoxicity after adjusting other confounding factors. Multivariate analysis also showed that BMI ≥ 23 kg/m 2 and baseline LVEF value < 62.5% increased cardiotoxicity 3.0 and 6.6 times, respectively. Our study showed that BMI ≥ 23 kg/m 2 , LVEF < 62.5%, and anthracycline-based chemotherapy were associated with time to trastuzumab-induced cardiotoxicity. Thus, close monitoring of cardiac function is recommended especially for patients using the above risk factors.

Purpose: How 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. Methods: Among 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. Results: Target 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). Conclusions: Both 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. [ABSTRACT FROM AUTHOR]