Dosimetric parameters associated with radiation-induced esophagitis in breast cancer patients undergoing regional nodal irradiation

Dose constraints in breast cancer radiotherapy. A critical review

Radiotherapy plays an essential role in the treatment of breast cancer (BC). Recent advances in treatment technology and radiobiological knowledge have a major impact in BC patients with locoregional disease as the majority are now long-term survivors. Over the last three decades, intensity-modulated radiotherapy (IMRT), volumetric-modulated arc therapy (VMAT) and deep inspiration breath-hold (DIBH) techniques, together with the increasing adoption of moderately hypofractionated and ultra-hypofractionated treatment schedules as well as the possibility to offer partial breast radiotherapy to a well-defined patient subset have significantly changed radiotherapy for BC patients. As dose-volume constraints (DVCs) have to be adapted to these new treatment paradigms we have reviewed available evidence-based data concerning dose-constraints for the main organs at risk (OARs) that apply to the treatment of whole breast/chest wall radiotherapy, whole breast/chest wall radiotherapy including regional nodal irradiation (RNI) and partial breast irradiation (PBI), for the most relevant fractionation schedules that have been introduced recently. This narrative review provides a comprehensive summary that may help to harmonize treatment planning strategies.

Dosimetric risk factors for radiation esophagitis in patients with breast cancer following regional nodal radiation

BACKGROUND

Radiation esophagitis (RE) is one of the most common clinical symptoms of regi-onal lymph node radiotherapy for breast cancer. However, there are fewer studies focusing on RE caused by hypofractionated radiotherapy (HFRT).

AIM

To analyze the clinical and dosimetric factors that contribute to the development of RE in patients with breast cancer treated with HFRT of regional lymph nodes.

METHODS

Between January and December 2022, we retrospectively analysed 64 patients with breast cancer who met our inclusion criteria underwent regional nodal intensity-modulated radiotherapy at a radiotherapy dose of 43.5 Gy/15F.

RESULTS

Of the 64 patients in this study, 24 (37.5%) did not develop RE, 29 (45.3%) developed grade 1 RE (G1RE), 11 (17.2%) developed grade 2 RE (G2RE), and none developed grade 3 RE or higher. Our univariable logistic regression analysis found G2RE to be significantly correlated with the maximum dose, mean dose, relative volume 20-40, and absolute volume (AV) 20-40. Our stepwise linear regression analyses found AV30 and AV35 to be significantly associated with G2RE (P < 0.001). The optimal threshold for AV30 was 2.39 mL [area under the curve (AUC): 0.996; sensitivity: 90.9%; specificity: 91.1%]. The optimal threshold for AV35 was 0.71 mL (AUC: 0.932; sensitivity: 90.9%; specificity: 83.9%).

CONCLUSION

AV30 and AV35 were significantly associated with G2RE. The thresholds for AV30 and AV35 should be limited to 2.39 mL and 0.71 mL, respectively.

Association of Radiation-Induced Acute Esophagitis With Dosimetric Parameters of Oesophagus in Breast Carcinoma Patients Receiving Supraclavicular Nodal Irradiation

INTRODUCTION

We conducted this investigation to ascertain the dosimetric properties such as the mean and maximum radiation dosage during radiotherapy as well as the extent of radiation exposure to the esophagus. These factors can potentially impact the development of esophagitis in breast cancer patients undergoing supraclavicular radiation.

METHODOLOGY

 From January to June 2023, an observational study was conducted at Bangabandhu Sheikh Mujib Medical University in Bangladesh. The patients received radiation therapy (40.05 Gy in 15 parts) to the chest wall and supraclavicular node for three weeks. We were able to guess the following from the dose volume histogram (DVH) data: the length of the esophagus in the treatment area (i.e., the size of the esophagus that was visible on the planning CT scan), the maximum dose (Dmax), the mean dose (Dmean), and the volume of the 10Gy (V10Gy) and 20Gy (V20Gy) doses that were given to the esophagus. During radiotherapy, patients were checked on once a week, and the radiotherapy oncology group was used to evaluate and grade esophagitis Results: Patients with left-sided breast cancer showed a higher Dmean, Dmax, and length of the esophagus compared to those with right-sided breast cancer. Specifically, the Dmean was 6.7 (±2.1) Gy, the Dmax was 39.2 (±1.5) Gy, and the length of the esophagus was 6.1 (±1.2) Gy. Patients with left breast cancer had elevated V10Gy and V20Gy values for the esophagus, but the difference was not statistically significant. The incidence of V10Gy for right-sided breast cancer and left-sided breast cancer was 4.2% (±2.6%) and 19.8% (±9.2%), respectively. The V20Gy was 2.4% (±0.9%) for right-sided breast cancer and 13.09% (±5.0%) for left-sided breast cancer Conclusion: In conclusion, there is a strong association between the mean oesophageal dose and radiation to the left supraclavicular region following surgery in women with breast cancer and acute esophagitis. We can reduce esophageal toxicity by prescribing dose restrictions and performing precise delineation of the esophagus.

Dose-Volume Predictors for Radiation Esophagitis in Patients With Breast Cancer Undergoing Hypofractionated Regional Nodal Radiation Therapy

PURPOSE

Our objective was to assess the incidence and dose-volume predictors of radiation esophagitis (RE) in patients with breast cancer undergoing hypofractionated regional nodal irradiation.

METHODS AND MATERIALS

Eligible patients who received intensity modulated radiation therapy (RT) at the chest wall, the supraclavicular/infraclavicular fossa, level II axilla, and/or the internal mammary chain after mastectomy were included. The prescribed dose was 43.5 Gy in 15 fractions. RE was evaluated weekly during RT and at 1 and 2 weeks, followed by 3 and 6 months after RT, and was graded according to National Cancer Institute Common Toxicity Criteria for Adverse Events, version 3.0. The esophagus was contoured from the lower border level of the cricoid cartilage to the lower margin of the aortic arch. Esophageal total volume, mean dose, maximum dose, and the relative volumes (RV) and absolute volumes (AV) receiving at least 5 to 45 Gy by 5-Gy increments (RV5-RV45 and AV5-AV45) were evaluated. Univariable and multivariable logistic regression analyses were performed to determine risk factors for RE, and receiver operating characteristic curves were obtained to identify the thresholds of esophageal dosimetric parameters.

RESULTS

In total, 298 patients were included between May 8, 2020, and January 5, 2022 (minimum post-RT follow-up: 6 months). Grade 2 and 3 RE incidence was 40.9% (122/298) and 0.3% (1/298), respectively. No grade 4 or 5 RE was observed. Esophageal RV20-RV40 and AV35-AV40 were significantly associated with the risk of grade ≥2 RE after adjusting for tumor laterality and internal mammary nodal irradiation. RV25 and AV35 were optimum dose-volume predictors for grade ≥2 RE at thresholds 20% for RV25 (35.9% vs 60.9%; P = .04) and 0.27 mL for AV35 (31.0% vs 54.6%; P = .04).

CONCLUSIONS

RE is common in patients with breast cancer undergoing hypofractionated regional nodal irradiation. Maintaining the upper esophageal V25 at <20% and V35 at <0.27 mL may decrease the risk of RE.

The Regulation of Exosome-Mediated miR-132-3p/miR-132-3p-UUU on Radiation-Induced Esophageal Injury

Radiation-induced esophageal injury (RIEI) is a major dose-limiting complication of radiotherapy, mainly acute esophagitis. However, understanding of radiation injury and repair mechanisms in esophageal epithelial cells remains limited. MiR-132-3p and its uridylated isoform (miR-132-3p-UUU) are upregulated in radiation esophageal injury, yet their role in radiation-induced esophageal injury progression remains unexplored. We expressed miR-132-3p and its uridine form in irradiated human esophageal epithelial cells (HEEC) and secreted exosomes was examined by real-time polymerase chain reaction (RT-PCR). Cell proliferation, migration, apoptosis and colony formation were used to determine biological effects. Cell cycle assays and dual luciferase reporter assays were used to assess the relationship between miR-132-3p and its uridylated isoforms and MEF2A. The addition of miR-132-3p mimics or overexpression of miR-132-3p significantly inhibited the proliferation and migration of esophageal epithelial cells (HEEC cells as well as primary cells) and increased radiation damage. This was reversed by its uridylated isoform by reducing binding to MEF2A and regulating the cell cycle. Furthermore, miR-132-3p and its triuridylated isomer also regulate apoptosis after irradiation through pathways other than reactive oxygen species (ROS). In conclusion, our data reveal that radiation-induced miR-132-3p uridylation and exosome-mediated intercellular communication and tri-uridylated isoforms are protective against radiation-induced esophageal injury. Furthermore, miR-132-3p offers new opportunities as a promising biomarker widely present in human body fluids for the prediction of radiation esophagitis as a biomarker.

Comparison of esophagus dose in breast cancer patients undergoing supraclavicular irradiation with and without esophagus countering

CONTEXT

Esophagus toxicity and the risk of esophageal cancer are linked to radiation dose to the esophagus in breast cancer patients undergoing supraclavicular irradiation.

AIMS

The aim of this study was to evaluate the impact of esophagus contouring on the dose received in the esophagus in breast cancer patients undergoing supraclavicular irradiation.

SETTING AND DESIGN

This study included 30 treatment plans for breast cancer patients who received 50 Gy/25 fractions (2 Gy/fraction/day) using 3D-conformal radiation therapy (3D-CRT) to the whole breast or chest wall and supraclavicular.

METHODS AND MATERIALS

Our study included two groups: the non-sparing group was the treatment plan in which the esophagus was not delineated and the esophagus sparing group was generated, in which the plans were modified to spare the esophagus. The maximum dose, mean dose, and percentage of esophagus volume received, 5, 10, 15, and 20 Gy, respectively (V5, V10, V15, and V20), were used to evaluate both groups.

STATISTICAL ANALYSIS

One-way analysis of variance was used. A P value <0.05 was considered statistically significant.

RESULTS

The esophagus sparing group plans show a reduction in the esophageal mean dose Dmean (5.72 ± 5.15) Gy when compared to the non-sparing group (7.83 ± 3.31) Gy. Likewise, the maximum dose, V5, V10, V15, and V20 were reduced in the esophagus sparing group. All dosimetric parameters were significantly higher (P < 0.05) in patients with left breast cancer for both groups.

CONCLUSION

Our results suggest that it is possible to reduce the dose to the esophagus by considering the esophagus during treatment planning while maintaining plan quality. This reduction could lead to the greatest predicted decrease in acute esophagitis and esophageal cancer.

Prediction Factors of Radiation Esophagitis in Breast Cancer Patients Undergoing Supraclavicular Radiotherapy

Purpose

The aim of this study was to investigate demographic and dosimetric parameters which may link with esophagitis in patients with breast cancer receiving three-dimensional conformal radiotherapy to the supraclavicular fossa.

Materials and Methods

We examined 27 breast cancer patients with supraclavicular metastases. All patients were treated with radiotherapy (RT) with a prescribed dose of 40.5 Gy in 15 fractions for 3 weeks. Esophagitis was recorded weekly and esophagus toxicity was evaluated and graded according to the tadiation therapy oncology group. The following factors were examined regarding their correlation with grade 1 or worse esophagitis by univariate and multivariate analyses: age, chemotherapy, smoking history, maximum dose (Dmax), mean dose (Dmean), esophagus volume receiving 10 Gy (V10), esophagus volume receiving 20 Gy (V20), and length of esophagus in the treatment field.

Results

Of 27, 11 (40.7%) patients developed no esophageal irritation throughout therapy. Approximately half of the patients 13/27 (48.1%) had maximum grade 1 esophagitis. 2/27 (7.4%) patients had grade 2 esophagitis. The incidence of grade 3 esophagitis was (3.7%). Dmean, Dmax, V10, and V20 were 10.48 ± 5.10 Gy, 38.18 ± 5.12Gy, 29.83 ± 15.16, and 19.32 ± 10.01, respectively. Our results showed that Dmean, V10, and V20 were the significant factors for the development of esophagitis, whereas esophagitis was not significantly associated with the chemotherapy regimen, age, and smoking status.

Conclusions

We found that Dmean, V10, and V20 correlated significantly with acute esophagitis. However, the chemotherapy regimen, age, and smoking status did not affect esophagitis development.

Integrated scoring approach to assess radiotherapy plan quality for breast cancer treatment

Background

Proposal of an integrated scoring approach assessing the quality of different treatment techniques in a radiotherapy planning comparison. This scoring method incorporates all dosimetric indices of planning target volumes (PTVs) as well as organs at risk (OARs) and provides a single quantitative measure to select an ideal plan.

Materials and methods

The radiotherapy planning techniques compared were field-in-field (FinF), intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), hybrid IMRT (H-IMRT), and hybrid VMAT (H-VMAT). These plans were generated for twenty-five locally advanced left-sided breast cancer patients. The PTVs were prescribed a hypofractionation dose of 40.5 Gy in 15 fractions. The integrated score for each planning technique was calculated using the proposed formula.

Results

An integrated score value that is close to zero indicates a superior plan. The integrated score that incorporates all dosimetric indices (PTVs and OARs) were 1.37, 1.64, 1.72, 1.18, and 1.24 for FinF, IMRT, VMAT, H-IMRT, and H-VMAT plans, respectively.

Conclusion

The proposed integrated scoring approach is scientific to select a better plan and flexible to incorporate the patient-specific clinical demands. This simple tool is useful to quantify the treatment techniques and able to differentiate the acceptable and unacceptable plans.

Exposure of the oesophagus in breast cancer radiotherapy: A systematic review of oesophagus doses published 2010-2020

BACKGROUND AND PURPOSE

Breast cancer radiotherapy can increase the risk of subsequent primary oesophageal cancer, with risk increasing according to oesophagus radiation dose. We describe oesophagus exposure from modern breast cancer regimens and discuss the risks of oesophageal cancer for women irradiated recently.

MATERIALS AND METHODS

A systematic review was undertaken of oesophagus doses from breast cancer radiotherapy regimens published during 2010-2020. Mean and maximum oesophagus doses were described for different target regions irradiated and different radiotherapy techniques.

RESULTS

In 112 published regimens from 18 countries, oesophagus doses varied with target region. For partial breast irradiation, average mean oesophagus dose was 0.2 Gy (range 0.1-0.4) in four regimens; maximum dose was not reported. For breast or chest wall radiotherapy, average oesophagus doses were mean 1.8 Gy (range 0.1-10.4) in 24 regimens and maximum 6.7 Gy (range 0.4-14.3) in seven regimens. For radiotherapy including a nodal region, average oesophagus doses were higher: mean 11.4 Gy (range <0.1-29.3) in 61 regimens and maximum 34.4 Gy (range 3.4-51.3) in 55 regimens. Average mean oesophagus doses were >10 Gy for intensity modulated nodal radiotherapy, but lower for other node techniques.

CONCLUSIONS

Mean oesophagus doses from partial breast and breast/chest wall regimens were usually less than 2 Gy, hence radiation-risks will be very small. However, for radiotherapy including lymph nodes, average mean oesophagus dose of 11.4 Gy may nearly double oesophageal cancer risk. Consideration of oesophageal exposure during nodal radiotherapy planning may reduce the risks of radiation-related oesophageal cancer for women irradiated today.

Comparison of dose volumetric parameters of oesophagus in the radiation treatment of carcinoma breast with and without oesophagus delineation

Aim:

There are only limited studies available in literature that discuss methods to reduce the oesophageal dose and acute oesophagitis during breast cancer radiotherapy. The aim of this study is to compare dose volumetric parameters of oesophagus in radiation treatment of breast with and without oesophagus delineation.

Methods:

Treatment plans of 44 patients, who underwent chest wall and supraclavicular fossa irradiation, were selected for the study. Oesophagus was later delineated and treatment replanned using three-dimensional conformal radiotherapy (3DCRT) considering oesophagus as an organ at risk (OAR). The dose prescribed was 40 Gy/15 fractions to the planning target volume (PTV). Dose volumetric parameters of oesophagus such as maximum dose (Dmax), mean dose (Dmean), the percentage of oesophagus volume receiving ≥15Gy (V15), ≥25Gy(V25), ≥33Gy(V33) and ipsilateral lung volume parameters V4, V8 and V16 were compared with already executed plans in which oesophagus was not delineated.

Results:

Contouring the oesophagus as an OAR as a part of the radiotherapy treatment for Carcinoma Breast resulted in statistically significant reduction in dose to the oesophagus. No statistically significant change was found in the ipsilateral lung volume parameters. No compromise in plan quality was required as evident from the statistically non-significant differences in Homogeneity index and Conformity index.

Findings:

3DCRT planning with oesophagus delineation can be considered as a method to reduce oesophageal dose and the acute oesophageal toxicity during radiotherapy for carcinoma breast.

Tricks and tips for target volume definition and delineation in breast cancer: Lessons learned from ESTRO breast courses

Delineation of target and 'organ at risk' volumes is a critical part of modern radiation therapy planning, the next essential step after deciding the indication, patient discussion and image acquisition. Adoption of volume-based treatment planning for non-metastatic breast cancer has increased greatly along with the use of improved planning techniques, essential for modern therapy. However, identifying the volumes on a planning CT is no easy task. The current paper is written by ESTRO's breast course faculty, providing tricks and tips for target volume definition and delineation for optimal postoperative breast cancer irradiation.

Predictors of Acute Radiation Dermatitis and Esophagitis in African American Patients Receiving Whole Breast Radiotherapy

PURPOSE/OBJECTIVES

Adjuvant whole breast radiotherapy following breast conserving surgery is standard of care in the management of early stage breast cancer. Two of the most common acute toxicities of breast radiotherapy are radiation esophagitis (RE) and radiation dermatitis (RD). African Americans are at higher risk for experiencing treatment-related toxicity and are often under-represented in clinical trials.

METHODS

An institutional database was developed to include all African American patients with history of breast cancer or DCIS undergoing adjuvant radiotherapy at a single institution from 2013-2019. Records were reviewed to identify patient age, BMI, radiation dose, prone vs supine position, inclusion of boost, and inclusion of regional nodal irradiation (RNI). Radiation treatment plans were reviewed to identify breast size as well as dosimetric parameters to the breast and esophagus. Medical records were reviewed to identify which patients were prescribed silvadene or mylanta-lidocaine during or immediately following their course of radiotherapy which was used as a surrogate for Grade 2 or higher dermatitis (G2RD) and esophagitis (G2RE), respectively.

RESULTS

272 patients were included in the final analysis. On univariable analysis, morbidly obese patients were more likely to develop G2RD while hypofractionated radiotherapy was associated with lower rates of G2RD. On multivariable analysis, increasing breast volume was associated with higher rates of G2RD. For the subset of patients receiving RNI, 19% of patients experienced G2RE with the best predictor on multivariable analysis being D_mean to the esophagus.

CONCLUSION

Radiation dermatitis and esophagitis are common toxicities in African American patients undergoing adjuvant breast radiotherapy. Breast size, irrespective of patient's BMI, was associated with worse rate of dermatitis. Prone position and hypofractionated radiation reduced rates of G2RD. D_mean to the esophagus was the dosimetric parameter best correlating with G2RE. These results may be used to help select patients are at higher risk for G2 or higher toxicity during radiotherapy.

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

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.

Clinical feasibility of deep learning-based auto-segmentation of target volumes and organs-at-risk in breast cancer patients after breast-conserving surgery

Background

In breast cancer patients receiving radiotherapy (RT), accurate target delineation and reduction of radiation doses to the nearby normal organs is important. However, manual clinical target volume (CTV) and organs-at-risk (OARs) segmentation for treatment planning increases physicians’ workload and inter-physician variability considerably. In this study, we evaluated the potential benefits of deep learning-based auto-segmented contours by comparing them to manually delineated contours for breast cancer patients.

Methods

CTVs for bilateral breasts, regional lymph nodes, and OARs (including the heart, lungs, esophagus, spinal cord, and thyroid) were manually delineated on planning computed tomography scans of 111 breast cancer patients who received breast-conserving surgery. Subsequently, a two-stage convolutional neural network algorithm was used. Quantitative metrics, including the Dice similarity coefficient (DSC) and 95% Hausdorff distance, and qualitative scoring by two panels from 10 institutions were used for analysis. Inter-observer variability and delineation time were assessed; furthermore, dose-volume histograms and dosimetric parameters were also analyzed using another set of patient data.

Results

The correlation between the auto-segmented and manual contours was acceptable for OARs, with a mean DSC higher than 0.80 for all OARs. In addition, the CTVs showed favorable results, with mean DSCs higher than 0.70 for all breast and regional lymph node CTVs. Furthermore, qualitative subjective scoring showed that the results were acceptable for all CTVs and OARs, with a median score of at least 8 (possible range: 0–10) for (1) the differences between manual and auto-segmented contours and (2) the extent to which auto-segmentation would assist physicians in clinical practice. The differences in dosimetric parameters between the auto-segmented and manual contours were minimal.

Conclusions

The feasibility of deep learning-based auto-segmentation in breast RT planning was demonstrated. Although deep learning-based auto-segmentation cannot be a substitute for radiation oncologists, it is a useful tool with excellent potential in assisting radiation oncologists in the future.

Trial registration Retrospectively registered.