Uncertainties in estimating heart doses from 2D-tangential breast cancer radiotherapy

Development of deep learning chest X-ray model for cardiac dose prediction in left-sided breast cancer radiotherapy

Deep inspiration breath-hold (DIBH) is widely used to reduce the cardiac dose in left-sided breast cancer radiotherapy. This study aimed to develop a deep learning chest X-ray model for cardiac dose prediction to select patients with a potentially high risk of cardiac irradiation and need for DIBH radiotherapy. We used 103 pairs of anteroposterior and lateral chest X-ray data of left-sided breast cancer patients (training cohort: n = 59, validation cohort: n = 19, test cohort: n = 25). All patients underwent breast-conserving surgery followed by DIBH radiotherapy: the treatment plan consisted of three-dimensional, two opposing tangential radiation fields. The prescription dose of the planning target volume was 42.56 Gy in 16 fractions. A convolutional neural network-based regression model was developed to predict the mean heart dose (∆MHD) reduction between free-breathing (MHD_FB) and DIBH. The model performance is evaluated as a binary classifier by setting the cutoff value of ∆MHD > 1 Gy. The patient characteristics were as follows: the median (IQR) age was 52 (47–61) years, MHD_FB was 1.75 (1.14–2.47) Gy, and ∆MHD was 1.00 (0.52–1.64) Gy. The classification performance of the developed model showed a sensitivity of 85.7%, specificity of 90.9%, a positive predictive value of 92.3%, a negative predictive value of 83.3%, and a diagnostic accuracy of 88.0%. The AUC value of the ROC curve was 0.864. The proposed model could predict ∆MHD in breast radiotherapy, suggesting the potential of a classifier in which patients are more desirable for DIBH.

Exposure of the heart and cardiac valves in women irradiated for breast cancer 1970-2009

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Cardiac exposure decreased substantially 1970–2009.

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Direct megavoltage IMC beams likely increase the risks of IHD and VHD.

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Cardiac dosimetry from past regimens is highly heterogeneous.

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Dosimetry from past decades is key for dose–response relationships for late effects.

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A wide variation in valve doses may enable a dose–response relationship for VHD.

Purpose

To describe cardiac exposure from breast cancer radiotherapy regimens used during 1970–2009 for the development of dose–response relationships and to consider the associated radiation-risks using existing dose–response relationships.

Material and methods

Radiotherapy charts for 771 women in the Netherlands selected for case control studies of heart disease after breast cancer radiotherapy were used to reconstruct 44 regimens on a typical CT-dataset. Doses were estimated for the whole heart (WH), left ventricle (LV) and cardiac valves.

Results

For breast/chest wall radiotherapy average WH doses decreased during 1970–2009. For internal mammary chain (IMC) radiotherapy WH doses were highest during the 1980s and 1990s when direct anterior fields were used and reduced in the 2000s when oblique fields were introduced. Average doses varied substantially for IMC regimens (WH 2–33 Gy, LV < 1–23 Gy). For cardiac valves, at least one valve received >30 Gy from most regimens.

Conclusions

Radiation-risks of IHD from breast/chest wall regimens likely reduced during 1970–2009. Direct anterior IMC regimens likely increased the risks of IHD and VHD over this time period but the use of oblique IMC fields from 2003 may have lowered these risks. These data provide a unique opportunity to develop dose–response relationships.

Preoperative spirometry and BMI in deep inspiration breath-hold radiotherapy: the early detection of cardiac and lung dose predictors without radiation exposure

Background

This study aimed to investigate preoperative spirometry and BMI as early predictors of the mean heart and lung dose (MHD, MLD) in deep inspiration breath-hold (DIBH) radiotherapy.

Methods

Left-sided breast cancer patients underwent breast-conserving surgery followed by DIBH radiotherapy enrolled. Patients who were not available for preoperative spirometry were excluded. One hundred eligible patients were performed free-breathing (FB-) CT and DIBH-CT for plan comparison. We completed the correlative and multivariate analysis to develop the linear regression models for dose prediction. The residuals were calculated to explore the unpreferable subgroups and compare the prediction accuracy.

Results

Among the parameters, vital capacity (VC) and BMI showed the strongest negative correlation with MHD (r = − 0.33) and MLD (r = − 0.34), respectively. They were also significant in multivariate analysis (P < 0.001). Elderly and less VC were independent predictors of increasing absolute residuals (AR). The VC model showed no significant difference in AR compared to the model using the CT parameter of lung volume in FB (LV-FB): median AR of the LV-FB model vs. the VC model was 0.12 vs. 0.11 Gy (P = 0.79). On the other hand, the median AR of the MLD model was 0.38 Gy, showing no specific subgroups of larger AR.

Conclusion

Preoperative spirometry and BMI are significant predictors of MHD and MLD, respectively. Although elderly and low-VC patients may have larger predictive variations, spirometry might be a substitute for LV-FB as a predictor of MHD.

Synthetic breath-hold CT generation from free-breathing CT: a novel deep learning approach to predict cardiac dose reduction in deep-inspiration breath-hold radiotherapy

Deep-inspiration breath-hold radiotherapy (DIBH-RT) to reduce the cardiac dose irradiation is widely used but some patients experience little or no reduction. We constructed and compared two prediction models to evaluate the usefulness of our new synthetic DIBH-CT (sCT) model. Ninety-four left-sided breast cancer patients (training cohort: n = 64, test cohort: n = 30) underwent both free-breathing and DIBH planning. The U-Net-based sCT generation model was developed to create the sCT treatment plan. A linear prediction model was constructed for comparison by selecting anatomical predictors of past literature. The primary prediction outcome is the mean heart dose (MHD) reduction, and the coefficient of determination (R2), root mean square error (RMSE) and mean absolute error (MAE) were calculated. Moreover, we evaluated the heart and lungs contours' similarity and Hounsfield unit (HU) difference between both images. The median MHD reduction was 1.14 Gy in DIBH plans and 1.09 Gy in sCT plans (P = 0.96). The sCT model achieved better performance than the linear model (R2: 0.972 vs 0.450, RMSE: 0.120 vs 0.551, MAE: 0.087 vs 0.412). The organ contours were similar between DIBH-CT and sCT: the median Dice (DSC) and Jaccard similarity coefficients (JSC) were 0.912 and 0.838 for the heart and 0.910 and 0.834 for the lungs. The HU difference in the soft-tissue region was smaller than in the air or bone. In conclusion, our new model can generate the affected CT by breath-holding, resulting in high performance and well-visualized prediction, which may have many potential uses in radiation oncology.

Identifying Surrogates for Heart and Ipsilateral Lung Dose to Guide Field Placement and Treatment Modality Selection during Virtual Simulation of Breast Radiotherapy

AIMS

Virtual simulation (VSim) of tangential photon fields is a common method of field localisation for breast radiotherapy. Heart and ipsilateral lung dose is unknown until the dosimetric plan is produced. If heart and ipsilateral lung tolerance doses are exceeded, this can prolong the pre-treatment pathway, particularly if a change of technique is required. The aim of this study was to identify predictive surrogates for heart and ipsilateral lung dose during VSim to aid optimum field placement and treatment modality selection.

MATERIALS AND METHODS

Computed tomography data from 50 patients referred for left breast/chest wall radiotherapy were retrospectively analysed (model-building cohort). The prescribed dose was 40.05 Gy in 15 fractions using a tangential photon technique. The heart and ipsilateral lung contours were duplicated, cropped to within the field borders and labelled heart-in-field (HIF) and ipsilateral lung-in-field (ILF). The percentage of HIF (%HIF) and ILF (%ILF) was calculated and correlated with mean heart dose (MHD) and volume of the ipsilateral lung receiving 18 Gy (V18Gy). Linear regression models were calculated. A validation cohort of 10 left- and 10 right-sided cases with an anterior supraclavicular fossa (SCF) field, and 10 left- and 10 right-sided cases including the internal mammary nodes using a wide tangential technique and anterior SCF field, tested the predictive model. Threshold values for %HIF and %ILF were calculated for clinically relevant MHD and ipsilateral lung V18Gy tolerance doses.

RESULTS

For the model-building cohort, the median %HIF and MHD were 2.6 (0.4-16.7) and 2.3 (1.2-8) Gy. The median %ILF and ipsilateral lung V18Gy were 12.1 (2.8-33.6) and 12.6 (3.3-35) %. There was a statistically significant strong positive correlation of %HIF with MHD (r2 = 0.97, P < 0.0001) and of %ILF with ipsilateral lung V18Gy (r2 = 0.99, P < 0.0001). For the validation cohort, the median %HIF and MHD were 3.9 (0.6-8) and 2.5 (1.4-4.7) Gy. The median %ILF and ipsilateral lung V18Gy were 20.1 (12.4-32.0) and 20.9 (12.4-34.4) %. The validation cohort confirmed that %HIF and %ILF continue to be predictive surrogates for heart and ipsilateral lung dose during VSim of left- and right-sided cases when including the SCF ± internal mammary nodes with a three-field photon technique.

DISCUSSION

The ability to VSim breast radiotherapy (±nodal targets) and accurately predict the heart and ipsilateral lung doses on the dosimetric plan will ensure that tolerance doses are not exceeded, and identify early in the pre-treatment pathway those cases where alternative techniques or modalities should be considered.

Risk of coronary artery disease after adjuvant radiotherapy in 29,662 early breast cancer patients: A population-based Danish Breast Cancer Group study

PURPOSE

Radiotherapy (RT) for early breast cancer (BC) reduces the risk of recurrence and improves overall survival. However, thoracic RT may cause some incidental RT dose to the heart with subsequent risk of heart disease. During 2000-2010, CT-based RT planning was gradually introduced. The aim of this study was to investigate the risk of cardiac events in left-sided compared with right-sided BC patients treated during a non-CT-based (1999-2007) vs a CT-based period (2008-2016).

MATERIAL AND METHODS

Information on BC and cardiac events among Danish women was obtained from population-based medical registers. Patients diagnosed with BC during 1999-2016, were included. A cardiac event was defined as coronary artery disease or severe valvular heart disease.

RESULTS

Among 29,662 patients, 22,056 received RT. For those irradiated during the non-CT-based period, the 10-year cumulative risk of cardiac event was 1.7% (95% CI 1.4-2.0) at median follow-up of 11.1 years. The incidence rate ratio (IRR) for cardiac event in left-sided vs right-sided patients was 1.44 (1.07-1.94) and a trend towards worse outcome was seen within the first 10 years after RT and approached statistical significance with longer follow-up. Among patients irradiated during the CT-based period, the 10-year cumulative risk of cardiac event was 2.1% (1.8-2.4) at median 6.8 years follow-up. The IRR for cardiac event in left-sided vs right-sided patients was 0.90 (0.69-1.16) and no trend towards worse outcome within the first 10 years was observed.

CONCLUSION

This study confirmed a higher risk of cardiac events in left-sided vs right-sided BC patients irradiated during a non-CT-based period. For patients irradiated during a CT-based period, no increased risk of cardiac events in left-sided vs right-sided patients was observed within the first 10 years after RT, whilst information on cardiac events beyond 10 years after RT was limited.

Dosimetric and isocentric variations due to patient setup errors in CT-based treatment planning for breast cancer by electronic portal imaging

BACKGROUND

Inaccuracies in treatment setup during radiation therapy for breast cancers may increase risks to surrounding normal tissue toxicities, i.e. organs at risks (OARs), and compromise disease control. This study was planned to evaluate the dosimetric and isocentric variations and determine setup reproducibility and errors using an online electronic portal imaging (EPI) protocol.

METHODS

A total of 360 EPIs in 60 patients receiving breast/chest wall irradiation were evaluated. Cumulative dose-volume histograms (DVHs) were analyzed for mean doses to lung (V20) and heart (V30), setup source to surface distance (SSD) and central lung distance (CLD), and shifts in anterior-posterior (AP), superior-inferior (SI), and medial lateral (ML) directions.

RESULTS

Random errors ranged from 2 to 3 mm for the breast/chest wall (medial and lateral) tangential treatments and 2-2.5 mm for the anterior supraclavicular nodal field. Systematic errors ranged from 3 to 5 mm in the AP direction for the tangential fields and from 2.5 to 5 mm in the SI and ML direction for the anterior supraclavicular nodal field. For right-sided patients, V20 was 0.69-3.96 Gy, maximum lung dose was 40.5 Gy, V30 was 1.4-3 Gy, and maximum heart dose was 50.5 Gy. Similarly, for left-sided patients, the CLD (treatment planning system) was 25 mm-30 mm, CLD (EPIs) was 30-40 mm, V20 was 0.9-5.9 Gy, maximum lung dose was 45 Gy, V30 was 2.4-4.1 Gy, and maximum heart dose was 55 Gy.

CONCLUSION

Online assessment of patient position with matching of EPIs with digitally reconstructed radiographs (DRRs) is a useful method in evaluation of interfraction reproducibility in breast irradiation.

Fully automated detection of heart irradiation in cine MV images acquired during breast cancer radiotherapy

PURPOSE

To develop robust automated detection of heart irradiation in continuous portal images (cine MV images) of tangential breast cancer treatments.

METHODS

Cine MV images of 302 tangential field deliveries were recorded for ten left-sided breast cancer patients receiving deep-inspiration breath-hold radiotherapy. An algorithm for fully automated heart edge detection in cine MV images was developed and tested for all images. The algorithm first enhances the heart edge contrast greatly by exploiting that pixels on the heart edge change their intensity cyclically, and highly correlated, at 1-3 Hz due to heartbeat. The algorithm then detects the heart edge in the enhanced image and calculates the exposed heart area within the field aperture.

RESULTS

The algorithm correctly identified the heart edge in all cine MV series with heart exposure (169 of 302 field deliveries). With conservative selection criteria the algorithm on average identified 70 heart edge pixels in the heart-including field deliveries (range: 10-230) without false positives. With less strict criteria 106 heart edge pixels were identified on average (range: 13-262) with 0.6% being false positives. The heart edge bordering the lung was segmented highly reliably even a few millimeters outside the field edge. For six patients with frequent heart irradiation, the exposed heart area showed large interfraction variations and smaller intrafraction variations.

CONCLUSIONS

Automated heart edge detection in cine MV images was proposed, developed and shown to be highly efficient for heart exposure detection in tangential breast fields. It may allow unsupervised surveillance of heart exposure at all tangential breast cancer treatments in a clinic.

Using a neural network to predict deviations in mean heart dose during the treatment of left-sided deep inspiration breath hold patients

PURPOSE

We investigated if a neural network could be used to predict the change in mean heart dose when a patient's heart deviates from its planned position during radiotherapy treatment.

METHODS

Predictions were made based on parameters available at the time of treatment planning. The dose prescription, deep inspiration breath-hold (DIBH) amplitude, heart volume, lung volume, V90% and mean heart dose were used to predict the increase in dose to the heart when a shift towards the treatment field was undertaken. The network was trained using 3 mm, 5 mm and 7 mm shifts in heart positions for 50 patients' giving 150 data points in total. The neural network architecture was also varied to find the most optimal network design. The final neural network was then tested using cross-validation to evaluate the model's ability to generalise to new data.

RESULTS

The optimal neural network found was comprised of a single hidden layer of 30 neurons. Based on twenty train/test splits, 94% of all prediction errors were below 0.2 Gy, 97.3% were below 0.3 Gy and 100% were below 0.5 Gy. The average RMSE and maximum prediction error over all train/test splits were 0.13 Gy and 0.5 Gy respectively.

CONCLUSIONS

Our approach using a neural network provides a clinically acceptable estimate of the increase in Mean Heart Dose (MHD), without the need for further imaging, contouring or evaluation. The trained neural network gives clinicians the information and tools required to evaluate what shift in heart position would be acceptable and which scenarios require immediate action before treatment continues.

Lipopolysaccharide-Binding Protein Is an Early Biomarker of Cardiac Function After Radiation Therapy for Breast Cancer

PURPOSE

To evaluate the prognostic potential of lipopolysaccharide-binding protein (LBP) levels after breast cancer radiation therapy (RT) for incipient cardiac dysfunction.

METHODS AND MATERIALS

In this single-centered study, we prospectively enrolled female patients treated for left breast cancer. Healthy age- and sex-matched participants were recruited as controls. LBP levels, cardiac troponin T, N-terminal propeptide of the brain natriuretic peptide, fatty acid binding protein, and C-reactive protein were assessed at three timepoints-before RT, after the last RT fraction, and 1 month after the last fraction. Echocardiographic evaluation was done 3 to 3.75 years after RT.

RESULTS

We recruited 51 patients and 78 controls. Baseline LBP concentrations in the study group were significantly higher than in controls at baseline (P < .001), at 24 hours, and at 1 month after RT (P = .003 and P < .001, respectively). Other biomarkers (cardiac troponin T, N-terminal propeptide of the brain natriuretic peptide, fatty acid binding protein, and C-reactive protein) did not differ in any of the timepoints. Posttreatment LBP concentrations were significantly and positively correlated with heart- and lung-associated dose-volume histogram variables. Posttreatment and follow-up LBP levels correlated positively with the E/E' echocardiographic index reflective of the diastolic function. After adjustment for left anterior descending artery mean dose, left ventricle mean dose, mean heart dose, and type of surgery, LBP remained significantly correlated with E/E' when measured 24 hours after RT (beta = 0.41, P = .032) and 1 month after RT (beta = 0.43, P = .028).

CONCLUSIONS

Serum LBP concentrations correlate with diastolic function evaluated 3 years after the completion of RT, making LBP a potentially useful prognostic parameter.

Feasibility of multi-atlas cardiac segmentation from thoracic planning CT in a probabilistic framework

Toxicity to cardiac and coronary structures is an important late morbidity for patients undergoing left-sided breast radiotherapy. Many current studies have relied on estimates of cardiac doses assuming standardised anatomy, with a calculated increase in relative risk of 7.4% per Gy (mean heart dose). To provide individualised estimates for dose, delineation of various cardiac structures on patient images is required. Automatic multi-atlas based segmentation can provide a consistent, robust solution, however there are challenges to this method. We are aiming to develop and validate a cardiac atlas and segmentation framework, with a focus on the limitations and uncertainties in the process. We present a probabilistic approach to segmentation, which provides a simple method to incorporate inter-observer variation, as well as a useful tool for evaluating the accuracy and sources of error in segmentation. A dataset consisting of 20 planning computed tomography (CT) images of Australian breast cancer patients with delineations of 17 structures (including whole heart, four chambers, coronary arteries and valves) was manually contoured by three independent observers, following a protocol based on a published reference atlas, with verification by a cardiologist. To develop and validate the segmentation framework a leave-one-out cross-validation strategy was implemented. Performance of the automatic segmentations was evaluated relative to inter-observer variability in manually-derived contours; measures of volume and surface accuracy (Dice similarity coefficient (DSC) and mean absolute surface distance (MASD), respectively) were used to compare automatic segmentation to the consensus segmentation from manual contours. For the whole heart, the resulting segmentation achieved a DSC of [Formula: see text], with a MASD of [Formula: see text] mm. Quantitative results, together with the analysis of probabilistic labelling, indicate the feasibility of accurate and consistent segmentation of larger structures, whereas this is not the case for many smaller structures, where a major limitation in segmentation accuracy is the inter-observer variability in manual contouring.

Model-based cardiac dose estimation in radiation treatment of left breast cancer

OBJECTIVE:

To develop a mathematical model for cardiac dose estimation for patients who have been treated for left-sided breast cancer without CT data.

METHODS:

After obtaining institutional review board approvals, 147 patients with left-sided breast cancer were selected that were treated supine with opposed tangents. The heart blocks from the tangential fields were removed and dose calculations were performed with 6 MV beams using an advanced algorithm. This study was performed with CT data with DRR to represent a radiographic simulator image of yesteryear treatments. The beam's eye-view images showing delineated breast, lung and heart were created to represent views on radiograph. The maximum heart distance (MHD) was recorded and irradiated heart area (AREA) was computed by combination of triangles and rectangles. Based on accurate 3D dose calculation, mean dose (D_mean) and V₁₀ to V₅₀ of heart were analyzed with respect to MHD and AREA for dosimetric parameters using linear and quadratic fit.

RESULTS:

The treatment parameters calculated by MHD and segments using 2D radiographs were within 2% of the actual dosimetric parameters computed from the 3D planning system. The MHD and AREA vs D_mean, V₁₀, V₂₀, V₃₀ and V₅₀ showed very good correlation with linear model (R² > 0.91); however the correlation was significantly better with quadratic model (R² > 0.92). The analysis of the dosimetric error with our linear and quadratic model is remarkable within <3% error for most cases.

CONCLUSION:

The proposed mathematical model for the cardiac dose estimation is accurate within ±3% using a radiograph without CT data. This provides avenues for patient pooling in future studies related to radiation dose and cardiac toxicity. These results will help in estimating cardiac dose analysis accurately from previous studies as well as in centers still using 2D planning.

ADVANCES IN KNOWLEDGE:

The evidence of cardiac risk following radiotherapy continues to be one of the important considerations for the management of left-sided breast cancer patients. One of the problem in the estimation of dose-risk effects is the reconstruction of heart dose for pre-CT treatments. In this study, a simple mathematical model is presented that could estimate cardiac dose within ±3% in left breast cancer treatment from 2D radiograph where CT data do not exist.

Quantification of heart, pericardium, and left ventricular myocardium movements during the cardiac cycle for thoracic tumor radiotherapy

Purpose

The purpose of this study was to quantify variations in the heart, pericardium, and left ventricular myocardium (LVM) caused by cardiac movement using the breath-hold technique.

Patients and methods

In this study, the electrocardiography-gated four-dimensional computed tomography (CT) images of 22 patients were analyzed, which were sorted into 20 phases (0-95%) according to the cardiac cycle. The heart, pericardium, and LVM were contoured on each phase of the CT images. The positions, volume, dice similarity coefficient (DSC) in reference to 0% phase, and morphological parameters (max 3D diameter, roundness, spherical disproportion, sphericity, and surface area) in different phases of the heart, pericardium, and LVM were analyzed, which were presented as mean ± standard deviation.

Results

The mean values of displacements along the X, Y, and Z axes respectively were as follows: 1.2 mm, 0.6 mm, and 0.6 mm for the heart; 0.5 mm, 0.4 mm, and 0.8 mm for the pericardium; and 1.0 mm, 4.1 mm, and 1.9 mm for the LVM. The maximum variations in volume and DSC respectively were 16.49%±3.85% and 10.08%±2.14% for the heart, 12.62%±3.94% and 5.20%±1.54% for the pericardium, and 24.23%±11.35% and 184.33%±128.61% for the LVM. The differences in the morphological parameters between the maximum and minimum DSC phases for the heart and pericardium were not significantly different (p>0.05) but were significantly different for the LVM (p<0.05).

Conclusion

The volumetric and morphological variations of the heart were similar to those of pericardium, and all were significantly smaller than those of the LVM. This inconsistency in the volumetric and morphological variations between the LVM and the heart and pericardium indicates that special protection of the LVM should be considered.

The potential benefits from respiratory gating for breast cancer patients regarding target coverage and dose to organs at risk when applying strict dose limits to the heart: results from the DBCG HYPO trial

PURPOSE

The potential benefits from respiratory gating (RG) compared to free-breathing (FB) regarding target coverage and dose to organs at risk for breast cancer patients receiving post-operative radiotherapy (RT) in the DBCG HYPO multicentre trial are reported.

MATERIAL AND METHODS

Patients included in the DBCG HYPO trial were randomized between 50 Gy in 25 fractions (normofractionated) versus 40 Gy in 15 fractions (hypofractionated). A tangential forward field-in-field dose planning technique was used to cover the clinical target volume (CTV) with the intent to limit dose to the left anterior descending coronary artery (LADCA) to 20 Gy and 17 Gy in the normo- and hypofractionated arms, respectively. Treatment plan data for 1327 patients from four Danish centres was retrospectively analyzed. FB right-sided patients served as control group for the left-sided patients regarding CTV V_95% (relative volume receiving at least 95% of the prescribed dose), mean heart dose (MHD) and mean lung dose (MLD).

RESULTS

Median CTV V_95% was for FB right-sided, FB left-sided and RG left-sided patients 94.6, 92.6 and 94.7% for normofractionated therapy, respectively, and 94.6, 91.8 and 94.4% for hypofractionated therapy and did not differ significantly for RG left-sided plans compared to FB right-sided in either study arm. CTV V_95% was significantly lower for FB versus RG for left-sided plans in both arms. Median MHD was 0.7, 1.8 and 1.5 Gy (normofractionated therapy) versus 0.6, 1.5 and 1.2 Gy (hypofractionated therapy), respectively. The corresponding median MLD was 9.0, 8.3 and 7.3 Gy versus 7.3, 6.4 and 5.8 Gy, respectively.

CONCLUSIONS

RG for left-sided breast cancer patients ensured similar CTV V_95% as for FB right-sided patients. MLD was lower for RG due to the increased lung volume. MHD was generally low due to strict protocol-defined maximum dose to LADCA, but for left-sided patients RG led to significantly lower MHD.

Are heart toxicities in breast cancer patients important for radiation oncologists? A practice pattern survey in German speaking countries

Background

To assess the personal beliefs of radiation oncologists regarding heart sparing techniques in breast cancer patients.

Methods

Between August 2015 and September 2015, a survey was sent to radiation oncology departments in Germany, Austria and Switzerland. 82 radiation oncology departments answered the questionnaire: 16 university clinics and 66 other departments. Most (87.2%) of the participants had >10 years of radiation oncology experience.

Results

89.2% of the participants felt that there is enough evidence to support heart sparing for breast cancer patients. The most important dose parameter was considered the mean heart dose (69.1%). The personal “safe” dose to the heart was considered to be 5 Gy (range: 0–40 Gy). The main impediment in offering all breast cancer patients heart-sparing techniques seems to be the fact that these techniques are time/ resource consuming (46.5% of the participants).

Conclusions

Most radiation oncologists believe that there is enough evidence to support heart sparing for breast cancer patients. But translating this belief into a wide practice will need better dosimetric and clinical data on what patients are expected to profit most, specific guidelines for which patients’ heart sparing techniques should be performed, as well as recognition of the time/resource consumption of these techniques.

Risk of heart disease in relation to radiotherapy and chemotherapy with anthracyclines among 19,464 breast cancer patients in Denmark, 1977-2005

BACKGROUND AND PURPOSE

The risk of heart disease subsequent to breast cancer radiotherapy was examined with particular focus on women receiving anthracycline-containing chemotherapy.

MATERIAL AND METHODS

Women diagnosed with early-stage breast cancer in Denmark, 1977-2005, were identified from the register of the Danish Breast Cancer Cooperative Group, as was information on cancer-directed treatment. Information on heart disease was sought from the Danish National Patient and Cause of Death Registries. Incidence rate ratios were estimated comparing left-sided with right-sided cancer (IRR, LvR), stratified by calendar year, age, and time since breast cancer radiotherapy.

RESULTS

Among 19,464 women receiving radiotherapy, the IRR, LvR, was 1.11 (95% CI 1.03-1.20, p=0.005) for all heart disease and among those also receiving anthracyclines the IRR, LvR, was 1.32 (95% CI 1.02-1.70, p=0.03). This risk was highest if the treatment was given before the age of 50years (IRR, LvR, 1.44, (95% CI 1.04-2.01) but there was no significant trend with age or time since treatment.

CONCLUSIONS

Radiotherapy for left-sided breast cancer is associated with a higher risk of heart disease than for right-sided with the largest increases seen in women who also received anthracycline-containing chemotherapy.