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Chen WY, Gan ZY, Cai YW, Hua ZQ, Yi L. Advances in deep inspiration breath-hold technique for radiotherapy of right-sided breast cancer. World J Transl Med 2026; 12(4): 126251 [DOI: 10.5528/wjtm.126251]
Author contributions: Chen WY and Yi L designed the research study; Chen WY, Gan ZY, Cai YW, and Hua ZQ performed the literature search and data extraction; Chen WY and Yi L analyzed and interpreted the data; Chen WY drafted the original manuscript; Yi L reviewed and edited the manuscript; and all authors have read and approved the final version.
AI contribution statement: In accordance with the artificial intelligence (AI) Tool Usage Policy of World Journal of Translational Medicine, the authors disclose the following use of AI tools during manuscript preparation. The authors take full responsibility and accountability for all content of this manuscript, including any portions for which AI tools were used as assistive technologies. All AI-assisted outputs were carefully reviewed, validated, and approved by the authors. AI tools were not used to generate original scientific data, perform independent scientific analyses, or draw scientific conclusions. (1) DeepSeek (AI language model, DeepSeek Inc.): Used for language editing and proofreading, including English-to-Chinese and Chinese-to-English translation assistance, language polishing, grammar correction, logical verification, and wording optimization. The use of this tool was limited to linguistic refinement and did not extend to generating scientific content, research data, or analytical conclusions; and (2) Minmo (AI-assisted coding assistant): Used to assist in writing and executing R code for generating Figure 1 (deep inspiration breath-hold clinical implementation workflow diagram). The tool assisted in code development and figure output; the conceptual design, clinical workflow logic, and final figure content were determined entirely by the authors. The manuscript text, core scientific viewpoints, research content, literature analysis, and scholarly interpretation are the original work of the authors.
Supported by the China Science Exchange Foundation (Biomedical Innovation and Development Technology Public Welfare Project), No. SWYY2026002205.
Conflict-of-interest statement: All authors declare that they have no conflict of interest to disclose.
Corresponding author: Liang Yi, MD, Department of Oncology, Yueyang Hospital Affiliated to Hunan Normal University, No. 263 Baling East Road, Yueyang 414000, Hunan Province, China. yiliangjs@126.com
Received: July 29, 2026 Revised: August 23, 2026 Accepted: October 9, 2026 Published online: November 28, 2026 Processing time: 98 Days and 12 Hours
Abstract
Deep inspiration breath-hold (DIBH) has become increasingly common in the postoperative radiotherapy of left-sided breast cancer, owing to its well-established role in sparing the heart and ipsilateral lung. For right-sided tumors, however, the clinical benefit of this technique is considerably less well defined. In most studies to date, DIBH has been shown to reduce both V20 and mean lung dose in right-sided breast cancer, with larger gains observed when regional nodal irradiation is included. The liver also appears to derive a dosimetric advantage. Cardiac findings are more mixed: While some reports indicate measurable reductions in whole-heart and right coronary artery doses, the decreases are typically small and exhibit substantial interpatient variability. Meanwhile, contralateral breast doses seem largely unaffected. Regarding breath-hold monitoring, the vast majority of investigations have utilized real-time position management or the optical surface monitoring system, whereas active breathing control has seen comparatively limited application in this context. Taken together, the existing evidence supports the use of right-sided DIBH for lung and liver protection; however, its value for the heart and contralateral breast remains uncertain, and further prospective studies are warranted to clarify these issues.
Core Tip: Deep inspiration breath-hold (DIBH) is well known for shielding the heart and lung during left-sided breast radiotherapy, but whether it helps right-sided patients remains unclear. For right-sided tumors, the main organs at risk include the lung on the same side, the liver, the heart, the right coronary artery, and the breast on the opposite side. Current data show that breath-hold can cut doses to the right lung and liver, yet it does not seem to spare the heart or the contralateral breast much. In practice, DIBH is mostly delivered with real-time position management or optical surface monitoring; active breathing control is rarely used in this context. More research is needed going forward.
Citation: Chen WY, Gan ZY, Cai YW, Hua ZQ, Yi L. Advances in deep inspiration breath-hold technique for radiotherapy of right-sided breast cancer. World J Transl Med 2026; 12(4): 126251
Currently, breast cancer remains the most common malignancy among women. Postoperative radiotherapy has been shown to reduce locoregional recurrence and improve survival, a benefit that is now well established[1]. In left-sided disease, the heart often lies within or adjacent to the tangential fields; the deep inspiration breath-hold (DIBH) technique, by expanding the lungs and reducing their density, displaces the heart posteriorly away from the chest wall, thereby lowering cardiac radiation dose and providing cardiac protection[2].
For right-sided breast radiotherapy, the principal organs at risk include the ipsilateral lung, liver, heart/right coronary artery (RCA), and the contralateral breast, with the corresponding toxicities being radiation pneumonitis, hepatopathy, late cardiac events, and secondary malignancies, respectively[3,4]. As survival improves, the impact of these toxicities has gained increasing attention, making dose reduction to these structures particularly important. However, the literature on the use of DIBH in right-sided breast cancer remains far more limited than that for left-sided disease, and its actual benefit is still not well defined.
This review focuses on the potential dosimetric advantages of DIBH for right-sided breast cancer, with particular emphasis on the ipsilateral lung, liver, heart and RCA, and the contralateral breast. In addition, the various methods for DIBH monitoring—including real-time position management (RPM), optical surface monitoring system (OSMS), and active breathing control (ABC)—are outlined, and the importance of respiratory management is also underscored.
DOSIMETRIC ADVANTAGES OF DIBH IN RIGHT-SIDED BREAST CANCER
Ipsilateral lung
For right-sided breast radiotherapy, the ipsilateral lung is the principal dose-limiting organ. DIBH contributes to dosimetric lung sparing through two synergistic mechanisms: Lung inflation increases total volume, thereby reducing the fraction of tissue receiving high doses, while the concomitant decrease in lung density lowers the energy deposited per unit mass. Together, these effects result in measurable dosimetric sparing of the right lung[5].
The majority of published studies have demonstrated that DIBH consistently reduces both V20 Gy and mean lung dose, and that the dosimetric benefit derives largely from density changes rather than from positional shift alone. Mader et al[5], in a series of 16 right-sided patients, reported a decline in V20 Gy from 14.0% to 11.5% with DIBH, accompanied by a drop in relative electron density from 0.62 to 0.59. Similar findings emerged from Haji et al[6] in 20 patients, where mean lung dose fell from 16.52 Gy to 13.77 Gy. The magnitude of lung sparing, however, is governed by anatomical factors, target volume, and treatment technique. More pronounced reductions in V20 and mean lung dose have been observed in plans that include regional nodal irradiation (RNI), whereas whole-breast-only plans show only marginal, and rarely significant, changes[7-11]. Treatment modality also matters: One study noted a significant V20 decrease with intensity modulated radiation therapy (IMRT) (11.3% to 9.7%, P < 0.001) but no such reduction with volumetric modulated arctherapy (VMAT) (29.9% vs 30.5%, P = 0.170)[12], a pattern earlier observed by Essers et al[13] as well. Collectively, these data suggest that patients receiving RNI or IMRT are the ones most likely to derive the most pronounced dosimetric improvement from DIBH. A summary of the reviewed studies and their lung dose parameters is provided in Tables 1 and 2 at the end of this article.
Table 1 Study characteristics of included publications.
The liver’s proximity to the right chest wall means that tangential or nodal fields for right-sided treatment can expose part of the liver. How much liver receives dose depends on field design, beam energy, and the anatomy between the liver dome and chest wall[3,4]. Breath-hold inflates the lungs and pushes the diaphragm down, widening the distance between the target and the liver tissue. This geometric effect is, somewhat unexpectedly, more pronounced for the liver than for the lung.
Haji et al[6] measured a mean liver dose reduction from 5.59 Gy to 2.54 Gy in 20 patients, with the absolute V20 volume decreasing from 148.38 mL to 64.19 mL. Mader et al[5] reported a larger change, with the maximum liver dose decreasing from 40.3 Gy to 17.5 Gy and V30 Gy reduced from 18.6 cm3 to zero. In their cohort of 54 RNI patients, Peters et al[8] found liver V20 decreasing from 78.8 mL to 23.9 mL and V30 from 58.1 mL to 14.6 mL (both P < 0.001). Conway et al[7] noted that V25 Gy decreased from 49.6 to 7.3 cc.
Several studies have evaluated how technique and technology affect hepatic sparing. Demiral et al[14], using ABC-based moderate DIBH in 36 right-sided patients, achieved a 61% reduction in mean liver dose (from 4.61 Gy to 178 cGy) and decreased the liver volume inside the planning target volume from 234.4 cc to 57.7 cc. Loap et al[15] treated 15 patients with VMAT and found that the median liver dose decreased from 2.54 Gy to 0.87 Gy (P = 0.01) under both conventional and hypofractionated regimens, although heart, coronary, and lung endpoints did not reach significance. Lai et al[16], in a study of 31 right-sided RNI patients using surface-guided radiotherapy (SGRT)-based breath-hold, reported a 69% reduction in mean liver dose (from 916.9 cGy to 281.2 cGy). Jiang et al[9] demonstrated reductions in mean liver dose from 5.6 Gy to 1.0 Gy for whole-breast plans and from 9.1 Gy to 2.6 Gy for chest-wall-plus-nodal plans in their 33-patient series. Lee et al[12] confirmed that liver D2cc decreased from 16.5 Gy to 2.7 Gy with IMRT and from 13.3 Gy to 3.0 Gy with VMAT. The data from the aforementioned literature are summarized in the tables below; study information is presented in Table 1, while liver data are provided in Table 3.
Table 3 Liver dosimetric outcomes (deep inspiration breath hold vs free breathing).
The heart is positioned farther from the right chest wall than from the left, resulting in generally lower cardiac doses in right-sided treatment. However, the RCA, which courses along the right atrioventricular groove, may receive significant exposure during tangential or RNI fields. In their study of 40 patients, Semiz et al[11] found that RCA Dmean decreased from 789 cGy to 512 cGy, and RCA Dmax reduced from 1547 cGy to 926 cGy in the breast-plus-RNI subgroup, with no significant change noted in the breast-only arm. The whole-heart Dmean decreased from 217 cGy to 37 cGy, and V5 declined from 21% to 16.2%[11]. Gough et al[10] reported RCA Dmean decreasing from 3.6 Gy to 3.0 Gy and Dmax from 8.6 Gy to 6.8 Gy in 14 patients. Borgonovo et al[17] indicated that breath-hold reduced both maximum and mean cardiac doses and decreased the maximum LAD dose in right-sided postoperative patients. Lai et al[16] documented heart Dmean reductions of 24.0% and RCA Dmax reductions of 46.7% in 31 patients.
Cardiac sparing is not consistently observed. Loap et al[15] reported no significant changes in mean heart dose, RCA dose, or other cardiac substructure doses, attributing this null result to the low baseline cardiac exposure associated with right-sided treatment. Similarly, Peters et al[8] reported non-significant heart dose reductions (mean heart dose 109.5 cGy vs 102.0 cGy, P = 0.175). Overall, the dosimetric benefit to the heart appears modest and variable, becoming most pronounced when RNI brings the high-dose region in proximity to the RCA (Tables 1 and 4).
Table 4 Heart, right coronary artery, and other organs at risk dosimetric outcomes.
Scatter dose to the contralateral (left) breast during right-sided irradiation is low in absolute terms, yet concerns regarding radiation-induced secondary malignancies warrant examination of any dose reductions. Jiang et al[9] found that contralateral breast Dmean decreased from 1.0 Gy to 0.9 Gy in whole-breast plans (P = 0.017), although the change did not achieve significance in chest-wall-plus-nodal plans. Conversely, Mader et al[5] observed an increase in contralateral breast Dmax from 0.63 Gy to 1.3 Gy with breath-hold, likely due to altered scatter geometry at full inspiration. Essers et al[13] detected no significant differences across treatment groups. Overall, contralateral breast sparing with DIBH is inconsistent and minor, and does not constitute a primary indication for its use in right-sided disease.
The only meta-analysis to date offers the strongest aggregate dosimetric evidence for DIBH in right-sided breast radiotherapy. Li et al[18] pooled seven studies covering 313 right-sided patients and found significant standardized mean differences favouring breath-hold over free breathing for heart Dmean (-0.63), liver Dmean (-1.15), total lung dose (-0.79), and right lung Dmean (-0.86) (all P < 0.05). Right lung V20 Gy, however, fell short of significance in the pooled analysis [standardized mean difference (SMD): -0.66, 95%CI: -1.50 to 0.18, P > 0.05], which the authors put down to inter-study variations in target design and baseline lung volume[18]. While this meta-analysis represents the best evidence we have, it is built solely on retrospective planning comparisons, and therefore carries the same methodological caveats as the studies it includes (Tables 1, 2, 3, and 4).
Recently, however, the magnitude of lung dose reduction achievable with DIBH has come under scrutiny. Mankinen et al[19] recalculated lung doses in 25 VMAT plans using deformable image registration (DIR) and found that the conventional dose-Volume Histogram (DVH) subtraction method overestimated the actual benefit of breath-hold. Their argument runs as follows: The lung does not inflate uniformly at deep inspiration—dependent regions expand less than the apices—and the resulting dose redistribution is not what a straightforward DVH subtraction would predict. After applying DIR correction, the reduction in V16 Gy was markedly attenuated, with only a modest dosimetric gain remaining[19].
It must be noted, however, that the study in question enrolled only left-sided breast cancer patients, from whose computed tomography scans right-sided VMAT plans were simulated by mirroring. Nor is this an isolated case—Pandeli et al[20] and Holt et al[21] adopted the same mirror-based approach. Yet genuine anatomical differences exist between the two sides: Rib curvature, the liver’s apposition to the chest wall, and cardiac geometry all diverge. Consequently, plans mirrored from the left side may fail to accurately represent the actual dose distribution encountered in right-sided radiotherapy. As a result, the true extent of any overestimation in the setting of actual right-sided anatomy remains unclear.
Clinical implications of dosimetric findings
The reductions in radiation dose to the various organs at risk described above are clinically meaningful in magnitude, yet whether these dosimetric benefits ultimately translate into improved patient outcomes remains to be confirmed. For the ipsilateral lung in particular, studies have reported fairly consistent reductions in both V20 and mean lung dose, and these two metrics are closely correlated with the risk of radiation pneumonitis[5-10,12,15-17]. What is missing is a head-to-head comparison of symptomatic pneumonitis rates between DIBH and free breathing in right-sided cohorts; without it, the degree to which dosimetric gains reduce pulmonary toxicity remains uncertain. Liver dosimetry looks similarly favorable: Mean liver dose reductions of 2-5 Gy and V20 decreases above 50% have been reported across several studies[5,6,8,9,15,16]. Dose is not the whole story, though—liver function is what matters at the bedside. Right-sided breast radiotherapy can perturb hepatic biological parameters. In a review of adjuvant radiotherapy’s hepatic effects, Hanedan Uslu and Taşçı[3] urged closer attention to liver constraints during planning. Lauffer et al[4] subsequently demonstrated measurable changes in both biological and clinical markers following right-sided irradiation. None of these studies, however, incorporated DIBH; whether the liver sparing it provides actually prevents detectable hepatic injury is therefore still unproven. Because right-sided tangential fields generally deliver lower cardiac doses, cardiac toxicity from right-sided breast radiotherapy is far less of a concern than in left-sided disease. Reported data on the sparing effect of DIBH on the heart and RCA vary considerably across studies[8,10,11,14,15]. And with no long-term cardiovascular follow-up data specifically for right-sided DIBH available, it remains unclear whether the dose reductions observed with breath-hold will ultimately translate into fewer late cardiac events.
BREATH-HOLD MANAGEMENT TECHNOLOGIES
Three principal monitoring methods support breath-hold radiotherapy delivery: RPM, OSMS, and ABC. RPM uses an infrared camera to track a reflective marker block placed on the patient’s abdomen. Treatment is gated—beam delivery occurs only when the respiratory trace falls within a user-defined breath-hold window. To date, RPM remains one of the most widely adopted respiratory gating tools in this field[5,10-13].
OSMS, also known as SGRT, employs ceiling-mounted stereo cameras to reconstruct a three-dimensional surface image of the patient’s torso. This enables real-time setup verification and breathing monitoring, eliminating the need for skin marks or implanted fiducials[22-27]. Several right-sided dosimetric studies have also utilized OSMS[6-9,15,16], and these data provide dosimetric support for the feasibility of SGRT-based DIBH in right-sided breast cancer.
ABC, in contrast, takes a fundamentally different approach. Rather than monitoring external motion, it uses a mouthpiece connected to a valve that occludes airflow at a preset lung volume—breath-hold is achieved through valve-controlled apnoea rather than patient-maintained gating. Studies of ABC in right-sided breast cancer are relatively scarce[14]. At present, no comparative data are available to establish the superiority of one method over the others.
Beyond hardware selection, several operational factors influence DIBH outcomes. Patient tolerance and compliance are key considerations in selecting candidates for breath-hold treatment[28,29]. Patient selection strategies further influence feasibility and dosimetric benefit[30,31]. Standardized breathing-training protocols support reproducibility across fractions[32-34]. This flowchart summarizes the DIBH treatment workflow for right-sided breast radiotherapy, which integrates published guidance on breath-hold implementation and the clinical practice of our institution, and is presented in Figure 1. The specific selection thresholds and ABC operational steps shown in the figure only represent the workflow of our institution, and should not be interpreted as recommendations from a universal guideline[35].
Figure 1 Treatment workflow for deep inspiration breath-hold in right-sided breast radiotherapy.
Three technology-specific pathways are shown: Pathway A (blue, RPM-based), pathway B [green, surface-guided radiotherapy/optical surface monitoring system (OSMS)-based], and Pathway C (amber, active breathing control-based). Shared pre-treatment steps [patient selection, deep inspiration breath-hold (DIBH) training, computed tomography simulation, and treatment planning] are indicated in indigo; per-fraction quality assurance is shown in violet. Pathway A: Real-time position management uses an infrared reflective marker block on the abdomen to track respiratory motion and gate beam delivery when a stable breath-hold position is confirmed. Pathway B: Surface-guided radiation therapy provides 6DOF real-time surface tracking without skin marks; OSMS acquires a DIBH reference surface for intra-fraction monitoring. Pathway C: The Active Breathing Coordinator closes a valve at a preset lung volume (75%-80% forced vital capacity), requiring bite-block insertion, system calibration, individualized threshold setting, and a 3-day coaching protocol to ensure reproducible breath-hold. All pathways converge at per-fraction quality assurance confirming target coverage, organ-at-risk sparing, and patient safety before each fraction. DIBH: Deep inspiration breath-hold; RPM: Real-time position management; SGRT: Surface-guided radiation therapy; OSMS: Optical surface monitoring system; ABC: Active breathing coordinator; FB: Free-breathing; CT: Computed tomography; OAR: Organs at risk; CBCT: Cone-beam computed tomography; kV: Kilovoltage; BB: Radiopaque body marker; BH: Breath-hold; 6DOF: Six degrees of freedom; FVC: Forced vital capacity.
FUTURE DIRECTIONS
Future research directions for DIBH in right-sided breast radiotherapy are likely to encompass further exploration of its potential dose-reducing effects on the heart and contralateral breast, with extended follow-up for long-term cardiac events and contralateral breast cancer incidence. Comparative investigations are also warranted to determine which respiratory monitoring platform confers greater benefit to patients receiving DIBH. In addition, standardization of breathing management protocols—including patient training, coaching quality, and reproducibility assurance—represents another avenue deserving systematic attention.
CONCLUSION
On balance, dosimetric studies suggest that DIBH in right-sided breast radiotherapy achieves meaningful dose reductions to the ipsilateral lung and liver. Its benefits for the heart, RCA, and contralateral breast, however, are less well supported by the available data. With respect to breath-hold monitoring techniques, the literature is dominated by RPM and OSMS, while studies employing ABC are comparatively scarce. Taken together, the case for right-sided DIBH is strongest for lung and liver sparing; whether it confers clinical advantages for the heart or contralateral breast awaits further investigation.
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