Dosimetric comparison of moderate deep inspiration breath-hold and free-breathing intensity-modulated radiotherapy for left-sided breast cancer

Cardiorespiratory dose comparison among six radiotherapy regimens for patients with left-sided breast cancer

There is uncertainty regarding the benefits and drawbacks of various radiation protocols for the treatment of left-sided breast cancer. To address this issue, we conducted a Bayesian network analysis. First, we searched several electronic databases for eligible literature. Next, we pooled the data from twelve studies concerning three-dimensional conformal radiation therapy (3D-CRT), intensity modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT), combined with either deep inspiratory breath-holding (DIBH) or free-breathing (FB) modalities. The integrated cardiac and pulmonary dosimetric indexes for all included treatments were compared using Bayesian networks. A direct meta-analysis indicated that for the two methods of 3D-CRT and IMRT, DIBH technology was more effective than FB in reducing the radiation dose to the heart and lungs. Additionally, according to the network results, DIBH was superior to FB in all six treatment options, regardless of whether the plan was 3D-CRT, IMRT, or VMAT. Besides, the combined data indicated that the FB-3D-CRT regimen had the weakest dosimetric advantage of all the treatments. Excluding FB-3D-CRT, each of the other five treatments had its own specific benefits. This is the first Bayesian study of several radiotherapy regimens for breast cancer patients on the left side, and the findings can be used to select appropriate radiotherapy programs for breast cancer patients.

Retrospective Analysis for Dose Reduction to Organs at Risk with New Personalized Breast Holder (PERSBRA) in Left Breast IMRT

This study evaluated dose differences in normal organs at risk, such as the lungs, heart, left anterior descending artery (LAD), right coronary artery, left ventricle, and right breast under personalized breast holder (PERSBRA), when using intensity-modulated radiation therapy (IMRT). This study evaluated the radiation protection offered by PERSBRA in left breast cancer radiation therapy. Here, we retrospectively collected data from 24 patients with left breast cancer who underwent breast-conserving surgery as well as IMRT radiotherapy. We compared the dose differences in target coverage and organs at risk with and without PERSBRA. For target coverage, tumor prescribed dose 95% coverage, conformity index, and homogeneity index were evaluated. For organs at risk, we compared the mean heart dose, mean left ventricle dose, LAD maximum and mean dose, mean left lung receiving 20 Gy, 10 Gy, and 5 Gy of left lung volume, maximum and mean coronary artery of the right, maximum of right breast, and mean dose. Good target coverage was achieved with and without PERSBRA. When PERSBRA was used with IMRT, the mean dose of the heart decreased by 42%, the maximum dose of LAD decreased by 26.4%, and the mean dose of LAD decreased by 47.0%. The mean dose of the left ventricle decreased by 54.1%, the volume (V₂₀) of the left lung that received 20 Gy decreased by 22.8%, the volume (V₁₀) of the left lung that received 10 Gy decreased by 19.8%, the volume (V₅) of the left lung that received 5 Gy decreased by 15.7%, and the mean dose of the left lung decreased by 23.3%. Using PERSBRA with IMRT greatly decreases the dose to organs at risk (left lung, heart, left ventricle, and LAD). This study found that PERSBRA with IMRT can achieve results similar to deep inspiration breath-hold radiotherapy (DIBH) in terms of reducing the heart radiation dose and the risk of developing heart disease in patients with left breast cancer who cannot undergo DIBH.

Comparison of Deep Inspiration Breath Hold Versus Free Breathing in Radiotherapy for Left Sided Breast Cancer

Objectives

Modern breast cancer techniques, such as the deep inspiration breath-hold (DIBH) technique has been applied for left-sided breast cancer. Whether the DIBH regimen is the optimal solution for left-sided breast cancer remains unclear. This meta-analysis aims to elucidate the differences of DIBH and free-breathing (FB) for patients receiving radiotherapy for left-sided breast cancer and provide a practical reference for clinical practice.

Methods

Relevant research available on PubMed, Embase, Cochrane Library, and the Web of Science published before November 30, 2021 was independently and systematically examined by two investigators. Data were extracted from eligible studies for assessing their qualities and calculating the standardized mean difference (SMD) and 95% confidence intervals (CIs) using Review Manager software 5.4 (RevMan 5.4).

Results

Forty-one studies with a total of 3599 left-sided breast cancer patients were included in the meta-analysis. Compared with FB, DIBH reduced heart dose (Dmean, Dmax, V30, V10, V5), left anterior descending branch (LAD) dose (Dmean, Dmax), ipsilateral lung dose (Dmean, V20, V10, V5), and heart volume significantly. Lung volume increased greatly, and a statistically significant difference. For contralateral breast mean dose, DIBH has no obvious advantage over FB. The funnel plot suggested this study has no significant publication bias.

Conclusions

Although DIBH has no obvious advantage over FB in contralateral breast mean dose, it can significantly reduce heart dose, LAD dose, ipsilateral lung dose, and heart volume. Conversely, it can remarkably increase the ipsilateral lung volume. This study suggests that soon DIBH could be more widely utilized in clinical practice because of its excellent dosimetric performance.

Quantifying inter- and intra-fraction variations of breast cancer radiotherapy with skin dose measurements

Aim. The aim of the current study was to compare between the deep inspiration breath-hold (DIBH) technique and free-breathing (FB) method in the treatment delivery uncertainty of breast cancer radiotherapy using skin dose measurements.Methods. In a prospective manner, eighty patients were randomly selected for skin dose measurements, and they were assigned to two groups. DIBH (40 patients) and FB (40 patients). The systematic inter-fraction dose variation was quantified using the mean percentage error (MPE) between the average measured total dose per session in three consecutive sessions and the corresponding calculated point dose from the treatment planning system. The random inter-fraction dose variation was quantified using the standard deviation (SD) of the dose delivered by the medial or lateral tangential fields, or the total session dose in the three sessions (SD_MT, SD_LT, or SD_total, respectively). While the random intra-fraction dose variation was quantified using the SD of the dose difference between the medial and lateral tangential fields in three consecutive sessions (SD_MT-LT).Results. There was no statistically significant difference in MPE between the DIBH and FB groups (p = 0.583). Moreover, the mean SD_totaland SD_MTof the DIBH group were significantly lower than that of the FB group (2.75 ± 2.33 cGy versus 4.45 cGy ± 4.33, p = 0.048) and (1.94 ± 1.63 cGy versus 3.76 ± 3.42 cGy, p = 0.007), respectively. However, there was no significant difference in the mean SD_LTand SD_MT-LTbetween the two groups (p > 0.05).Conclusion. In addition to the advantage of reducing the cardiopulmonary radiation doses in left breast cancer, the DIBH technique could reduce the treatment delivery uncertainty compared to the FB method due to the significant reduction in the random inter-fraction dose variations.

A seven-year experience of using moderate deep inspiration breath-hold for patients with early-stage breast cancer and dosimetric comparison

We present our seven-year experience of using moderate deep inspiration breath-hold (mDIBH) with an active breathing control (ABC) device for patients with early-stage breast cancer and dosimetric comparison to evaluate the benefit of mDIBH on the heart, lung, and liver.We retrospectively reviewed all patients with newly diagnosed breast cancer and having clinical stage Tis, I, or II disease treated between November 2010 and October 2017. Among the 369 patients included in this study, 107 patients were treated with mDIBH and 262 patients were treated with free breathing (FB). Dosimetric analysis was performed to compare dose distribution in the heart, lung, and liver between the two treatment groups. The chi-square test was used to compare the distribution of stage and tumor site between the two groups. The independent samples t-test was used to compare the remaining parameters between the two groups.For all 369 patients, there was a significantly lower ipsilateral lung V5 (relative volume receiving ≧5 Gy), ipsilateral lung V10, ipsilateral lung V20, mean ipsilateral lung dose, whole lung V5, whole lung V10, whole lung V20, mean whole lung dose, heart V10, heart V30, heart V40, and mean heart dose in the mDIBH group. For 184 patients with a left-sided breast tumor, significantly lower ipsilateral lung V5, ipsilateral lung V10, ipsilateral lung V20, mean ipsilateral lung dose, whole lung V10, whole lung V20, mean whole lung dose, heart V10, heart V30, heart V40, and mean heart dose were observed in the mDIBH group. For 185 patients with a right-sided breast tumor, significantly lower ipsilateral lung V5, ipsilateral lung V10, ipsilateral lung V20, mean ipsilateral lung dose, whole lung V5, whole lung V10, whole lung V20, mean whole lung dose, heart V10, heart V30, heart V40, mean heart dose, liver V30, and mean liver dose were observed in the mDIBH group.For early-stage breast cancer patients, mDIBH reduces not only the heart dose but also the lung and liver doses. The routine integration of mDIBH using an ABC device may decrease radiation-induced toxicity in the heart, lung, and liver.

MEDiastinal Irradiation and CArdio-Toxic Effects (MEDICATE): Exploring the Relationship between Cardiac Irradiation and High Sensitivity Troponins

AIMS

Radiation-induced heart disease is a late effect of cardiac irradiation and has been shown in patients with lymphoma and thoracic cancers. There is no established measurement tool to detect acute cardiac damage. However, high sensitivity troponin I and T (HsTnI and HsTnT) and echocardiograms have shown promise in some studies. A pilot trial was conducted to characterise whether these instruments may detect subclinical radiotherapy-induced cardiac damage.

MATERIALS AND METHODS

Eligible patients received high cardiac doses defined by either at least 30 Gy to 5% of cardiac volume or a mean dose of 4 Gy. HsTnI and HsTnT were measured before radiotherapy and after 2 and 4 weeks of radiotherapy; three-dimensional echocardiograms were completed before and 1 year after radiotherapy.

RESULTS

Of 19 patients, the median 'mean left ventricular dose' was 3.1 Gy and the 'mean cardiac dose' was 8.6 Gy. Significant positive associations between HsTnI and HsTnT were observed at all time points, but there was no significant association with cardiac dose. The mean left ventricular dose and the maximum left ventricular dose were, however, associated with a decrease in ejection fraction (P = 0.054, 0.043) as well as an increase in left ventricular strain (P = 0.058).

CONCLUSION

This study suggests that HsTnI and HsTnT are intimately related, but detection of acute cardiac damage was not shown, potentially due to limitations of these markers or low radiotherapy doses using conformal techniques. Our results also suggest subacute damage at 1 year may depend on the dose to the left ventricle. Further studies are needed, as identification of early damage could facilitate the ability to closely monitor and intervene in patients at risk for radiation-induced heart disease.

Dosimetric evaluation and systematic review of radiation therapy techniques for early stage node-negative breast cancer treatment

Radiation therapy (RT) is essential in treating women with early stage breast cancer. Early stage node-negative breast cancer (ESNNBC) offers a good prognosis; hence, late effects of breast RT becomes increasingly important. Recent literature suggests a potential for an increase in cardiac and pulmonary events after RT. However, these studies have not taken into account the impact of newer and current RT techniques that are now available. Hence, this review aimed to evaluate the clinical evidence for each technique and determine the optimal radiation technique for ESNNBC treatment. Currently, six RT techniques are consistently used and studied: 1) prone positioning, 2) proton beam RT, 3) intensity-modulated RT, 4) breath-hold, 5) partial breast irradiation, and 6) intraoperative RT. These techniques show dosimetric promise. However, limited data on late cardiac and pulmonary events exist due to challenges in long-term follow-up. Moving forward, future studies are needed to validate the efficacy and clinical outcomes of these current techniques.

Risks and benefits of reducing target volume margins in breast tangent radiotherapy

This study investigates the potential benefits of planning target volume (PTV) margin reduction for whole breast radiotherapy in relation to dose received by organs at risk (OARs), as well as reductions in radiation-induced secondary cancer risk. Such benefits were compared to the increased radiation-induced secondary cancer risk attributed from increased ionizing radiation imaging doses. Ten retrospective patients' computed tomography datasets were considered. Three computerized treatment plans with varied PTV margins (0, 5 and 10 mm) were created for each patient complying with the Radiation Therapy Oncology Group (RTOG) 1005 protocol requirements. The BEIR VII lifetime attributable risk (LAR) model was used to estimate secondary cancer risk to OARs. The LAR was assessed for all treatment plans considering (a) doses from PTV margin variation and (b) doses from two (daily and weekly) kilovoltage cone beam computed tomography (kV CBCT) imaging protocols during the course of treatment. We found PTV margins from largest to smallest resulted in a mean OAR relative dose reduction of 31% (heart), 28% (lung) and 23% (contralateral breast) and the risk of radiation-induced secondary cancer by a relative 23% (contralateral breast) and 22% (contralateral lung). Daily image-guidance using kV CBCT increased the risk of radiation induced secondary cancer to the contralateral breast and contralateral lung by a relative 1.6-1.9% and 1.9-2.5% respectively. Despite the additional dose from kV CBCT for the two considered imaging protocols, smaller PTV margins would still result in an overall reduction in secondary cancer risk.

[Establishing margins from CTV to PTV in breast cancer treatment]

The benefit of postoperative radiotherapy for breast cancer both in terms of local control and overall survival is widely acknowledged. Today, technological advances in simulation imaging and positioning control enable the definition of new margins from CTV to PTV. Improvements in mathematical modeling of random and systematic errors impact the treatment plans. However, there is no universal absolute value to consistently determine the margins from CTV to PTV. It is down to each centre to assess and correct as much as possible uncertainties due to positioning and internal movements depending on techniques and methods used for the implementation of treatment and monitoring. IMRT and respiratory gating techniques for breast radiotherapy will be considered more systematically in the years to come.