A Randomized Comparison of Radiation Therapy Techniques in the Management of Node-Positive Breast Cancer: Primary Outcomes Analysis

Evaluation of robustness of optimization methods in breast intensity-modulated radiation therapy using TomoTherapy

Intensity-modulated radiation therapy (IMRT) has become a popular choice for breast cancer treatment. We aimed to evaluate and compare the robustness of each optimization method used for breast IMRT using TomoTherapy. A retrospective analysis was performed on 10 patients with left breast cancer. For each optimization method (clipping, virtual bolus, and skin flash), a corresponding 50 Gy/25 fr plan was created in the helical and direct TomoTherapy modes. The dose-volume histogram parameters were compared after shifting the patients anteriorly and posteriorly. In the helical mode, when the patient was not shifted, the median D1cc (minimum dose delivered to 1 cc of the organ volume) of the breast skin for the clipping and virtual bolus plans was 52.2 (interquartile range: 51.9-52.6) and 50.4 (50.1-50.8) Gy, respectively. After an anterior shift, D1cc of the breast skin for the clipping and virtual bolus plans was 56.0 (55.6-56.8) and 50.9 (50.5-51.3) Gy, respectively. When the direct mode was used without shifting the patient, D1cc of the breast skin for the clipping, virtual bolus, and skin flash plans was 52.6 (51.9-53.1), 53.4 (52.6-53.9), and 52.3 (51.7-53.0) Gy, respectively. After shifting anteriorly, D1cc of the breast skin for the clipping, virtual bolus, and skin flash plans was 55.6 (54.1-56.4), 52.4 (52.0-53.0), and 53.6 (52.6-54.6) Gy, respectively. The clipping method is not sufficient for breast IMRT. The virtual bolus and skin flash methods were more robust optimization methods according to our analyses.

Lung-heart toxicity in a randomized clinical trial of hypofractionated image guided radiation therapy for breast cancer

Background

TomoBreast hypothesized that hypofractionated 15 fractions/3 weeks image-guided radiation therapy (H-IGRT) can reduce lung-heart toxicity, as compared with normofractionated 25-33 fractions/5-7 weeks conventional radiation therapy (CRT).

Methods

In a single center 123 women with stage I-II operated breast cancer were randomized to receive CRT (N=64) or H-IGRT (N=59). The primary endpoint used a composite four-items measure of the time to 10% alteration in any of patient-reported outcomes, physician clinical evaluation, echocardiography or lung function tests, analyzed by intention-to-treat.

Results

At 12 years median follow-up, overall and disease-free survivals between randomized arms were comparable, while survival time free from alteration significantly improved with H-IGRT which showed a gain of restricted mean survival time of 1.46 years over CRT, P=0.041.

Discussion

The finding establishes TomoBreast as a proof-of-concept that hypofractionated image-guided radiation-therapy can improve the sparing of lung-heart function in breast cancer adjuvant therapy without loss in disease-free survival. Hypofractionation is advantageous, conditional on using an advanced radiation technique. Multicenter validation may be warranted.

Trial registration

https://clinicaltrials.gov/ct2/show/NCT00459628. Registered 12 April 2007.

Integrating subvolume dose and myocardial perfusion imaging parameters to assess the impact of radiation therapy on heart function in breast cancer patients: A comparative analysis between left- and right-sided breast cancer

BACKGROUND

This study aimed to utilize an innovative method of integrating the 20 subvolume dose of left ventricle and the Tl-201 single photon emission computed tomography (SPECT) with myocardial perfusion imaging (MPI) parameters in patients with left- and right-sided breast cancer after radiation therapy.

METHODS

Female patients with breast cancer underwent SPECT MPI before commencing radiotherapy and 12 months later were enrolled from January 2014 to December 2018. The images of CT simulation and SPECT MPI were integrated into the treatment planning system. The differences of doses and parameters of MPI in all cardiac subvolumes between left- and right-sided breast cancer patients were analyzed.

RESULTS

Patients with left-sided breast cancer (n = 61) received a higher radiation dose to the heart, left ventricular, and its territories and subvolumes, compared to patients with right-sided breast cancer (n = 19). The 20-segment analysis also showed statistically significant disparities in the average radiation doses received by the two groups. In different coronary artery territories, the end-diastolic perfusion and end-systolic perfusion showed a decrease in both sides, with no significant differences. However, the wall motion and wall thickening showed a significant decline in subregions within the left- and right-sided coronary artery territories.

CONCLUSION

This study demonstrates an innovative integrated method combining the left ventricular 20 regional doses with SPECT MPI which shows that left-sided breast cancer patients receive a higher subvolume dose than right-sided breast cancer patients. Further research is needed to confirm the potential impact on heart function after radiotherapy on both sides.

Voluntary versus mechanically-induced deep inspiration breath-hold for left breast cancer: A randomized controlled trial

BACKGROUND AND PURPOSE

Deep inspiration breath-hold (DIBH) protects critical organs-at-risk (OARs) for adjuvant breast radiotherapy. Guidance systems e.g. surface guided radiation therapy (SGRT) improve the positional breast reproducibility and stability during DIBH. In parallel, OARs sparing with DIBH is enhanced through different techniques e.g. prone position, continuous positive airway pressure (CPAP). By inducing repeated DIBH with the same level of positive pressure, mechanically-assisted and non-invasive ventilation (MANIV) could potentially combine these DIBH optimizations.

MATERIALS AND METHODS

We conducted a randomized, open-label, multicenter and single-institution non-inferiority trial. Sixty-six patients eligible for adjuvant left whole-breast radiotherapy in supine position were equally assigned between mechanically-induced DIBH (MANIV-DIBH) and voluntary DIBH guided by SGRT (sDIBH). The co-primary endpoints were positional breast stability and reproducibility with a non-inferiority margin of 1 mm. Secondary endpoints were tolerance assessed daily via validated scales, treatment time, dose to OARs and their inter-fraction positional reproducibility.

RESULTS

Differences between both arms for positional breast reproducibility and stability occurred at a sub-millimetric level (p < 0.001 for non-inferiority). The left anterior descending artery near-max dose (14,6 ± 12,0 Gy vs. 7,7 ± 7,1 Gy, p = 0,018) and mean dose (5,0 ± 3,5 Gy vs. 3,0 ± 2,0 Gy, p = 0,009) were improved with MANIV-DIBH. The same applied for the V_5Gy of the left ventricle (2,4 ± 4,1 % vs. 0,8 ± 1,6 %, p = 0,001) as well as for the left lung V_20Gy (11,4 ± 2,8 % vs. 9,7 ± 2,7 %, p = 0,019) and V_30Gy (8,0 ± 2,6 % vs. 6,5 ± 2,3 %, p = 0,0018). Better heart's inter-fraction positional reproducibility was observed with MANIV-DIBH. Tolerance and treatment time were similar.

CONCLUSION

Mechanical ventilation provides the same target irradiation accuracy as with SGRT while better protecting and repositioning OARs.

Surface guided 3DCRT in deep-inspiration breath-hold for left sided breast cancer radiotherapy: implementation and first clinical experience in Iran

Background

The aim of the study is to evaluate the overall accuracy of the surface-guided radiotherapy (SGRT) workflow through a comprehensive commissioning and quality assurance procedures and assess the potential benefits of deep-inspiration breath-hold (DIBH) radiotherapy as a cardiac and lung dose reduction approach for left-sided breast cancer irradiation.

Materials and methods

Accuracy and reproducibility of the optical surface scanner used for DIBH treatment were evaluated using different phantoms. Patient positioning accuracy and reproducibility of DIBH treatment were evaluated. Twenty patients were studied for treatment plan quality in target dose coverage and healthy organ sparing for the two different treatment techniques.

Results

Reproducibility tests for the surface scanner showed good stability within 1 mm in all directions. The maximum position variation between applied shifts on the couch and the scanner measured offsets is 1 mm in all directions. The clinical study of 200 fractions showed good agreement between the surface scanner and portal imaging with the isocenter position deviation of less than 3 mm in each lateral, longitudinal, and vertical direction. The standard deviation of the DIBH level showed a value of < 2 mm during all evaluated DIBHs. Compared to the free breathing (FB) technique, DIBH showed significant reduction of 48% for heart mean dose, 43% for heart V25, and 20% for ipsilateral lung V20.

Conclusion

Surface-guided radiotherapy can be regarded as an accurate tool for patient positioning and monitoring in breast radiotherapy. DIBH treatment are considered to be effective techniques in heart and ipsilateral lung dose reductions for left breast radiotherapy.

Mediators of Racial Disparities in Heart Dose Among Whole Breast Radiotherapy Patients

BACKGROUND

Racial disparities in survival of patients with cancer motivate research to quantify treatment disparities and evaluate multilevel determinants. Previous research has not evaluated cardiac radiation dose in large cohorts of breast cancer patients by race nor examined potential causes or implications of dose disparities.

METHODS

We used a statewide consortium database to consecutively sample 8750 women who received whole breast radiotherapy between 2012 and 2018. We generated laterality- and fractionation-specific models of mean heart dose. We generated patient- and facility-level models to estimate race-specific cardiac doses. We incorporated our data into models to estimate disparities in ischemic cardiac event development and death. All statistical tests were 2-sided.

RESULTS

Black and Asian race independently predicted higher mean heart dose for most laterality-fractionation groups, with disparities of up to 0.42 Gy for Black women and 0.32 Gy for Asian women (left-sided disease and conventional fractionation: 2.13 Gy for Black women vs 1.71 Gy for White women, P < .001, 2-sided; left-sided disease and accelerated fractionation: 1.59 Gy for Asian women vs 1.27 Gy for White women, P = .002). Patient clustering within facilities explained 22%-30% of the variability in heart dose. The cardiac dose disparities translated to estimated excesses of up to 2.6 cardiac events and 1.3 deaths per 1000 Black women and 0.7 cardiac events and 0.3 deaths per 1000 Asian women vs White women.

CONCLUSIONS

Depending on laterality and fractionation, Asian women and Black women experience higher cardiac doses than White women. This may translate into excess radiation-associated ischemic cardiac events and deaths. Solutions include addressing inequities in baseline cardiac risk factors and facility-level availability and use of radiation technologies.

Volumetric modulated arc therapy (VMAT): a review of clinical outcomes—what is the clinical evidence for the most effective implementation?

Modern conformal radiation therapy using techniques such as modulation, image guidance and motion management have changed the face of radiotherapy today offering superior conformity, efficiency, and reproducibility to clinics worldwide. This review assesses the impact of these advanced radiotherapy techniques on patient toxicity and survival rates reported from January 2017 to September 2020. The main aims are to establish if dosimetric and efficiency gains correlate with improved survival and reduced toxicities and to answer the question ‘What is the clinical evidence for the most effective implementation of VMAT?’. Compared with 3DCRT, improvements have been reported with VMAT in prostate, locally advanced cervical carcinoma and various head and neck applications, leading to the shift in technology to VMAT. Other sites such as thoracic neoplasms and nasopharyngeal carcinomas have observed some improvement with VMAT although not in line with improved dosimetric measures, and the burden of toxicity and the incidence of cancer related deaths remain high, signaling the need to further mitigate toxicity and increase survival. As technological advancement continues, large randomised long-term clinical trials are required to determine the way-forward and offer site-specific recommendations. These studies are usually expensive and time consuming, therefore utilising pooled real-world data in a prospective nature can be an alternative solution to comprehensively assess the efficacy of modern radiotherapy techniques.

Heart Sparing Radiotherapy Techniques in Breast Cancer: A Focus on Deep Inspiration Breath Hold

Adjuvant radiation therapy is a critical component of breast cancer management. However, when breast cancer patients receive incidental radiation to the heart, there is an increased risk of cardiac disease and mortality. This is most common for patients with left-sided breast cancers and those receiving nodal irradiation as part of treatment. The overall risk of cardiac toxicity increases 4–16% with each Gray increase in mean heart radiation dose, with data suggesting that no lower limit exists which would eliminate cardiac risk entirely. Radiation techniques have improved over time, leading to lower cardiac radiation exposure than in the past. This decline is expected to reduce the incidence of radiation-induced heart dysfunction in patients. Deep inspiration breath hold (DIBH) is one such technique that was developed to reduce the risk of cardiac death and coronary events. DIBH is a non-invasive approach that capitalizes on the natural physiology of the respiratory cycle to increase the distance between the heart and the therapeutic target throughout the course of radiation therapy. DIBH has been shown to decrease the mean incidental radiation doses to the heart and left anterior descending coronary artery by approximately 20–70%. In this review, we summarize different techniques for DIBH and discuss recent data on this technique.

Cardiac Function after Modern Radiation Therapy with Volumetric Modulated Arc Therapy or Helical Tomotherapy for Advanced Left-Breast Cancer Receiving Regional Nodal Irradiation

Background: Protecting cardiac function in patients with advanced left-breast cancer receiving radiation therapy (RT) with regional nodal irradiation (RNI) is an important issue. Modern RT techniques can limit cardiac exposure. The aim of this study was to explore the association be-tween cardiac dose and cardiac function. Methods: Between 2017 and 2020, we retrospectively reviewed left-breast cancer patients who received adjuvant RT, including RNI with either volumetric-modulated arc therapy (VMAT) or helical tomotherapy (HT). Left ventricular ejection fraction (LVEF) was assessed by echocardiography before RT and 1 year after RT to detect any early deterioration in cardiac systolic function. Results: A total of 30 eligible patients were enrolled. The median follow-up time from the initiation of RT was 3.9 years (range 0.6–5 years). Seventeen patients received VMAT, and the other 13 patients received HT. The median RT dose was 55 Gray (Gy), and the mean heart dose was 3.73 Gy (range 1.95–9.36 Gy). The median LVEF before and after RT was 68% and 68.5%, respectively. No obvious deterioration was found. There was no association between cardiac dose (mean heart dose, V5–V30) and LVEF (change in values or post-RT). Conclusions: For left-breast cancer patients undergoing RT with RNI, VMAT, or HT can be used to limit cardiac exposure. Cardiac function as evaluated by LVEF revealed no obvious deterioration after RT in our patients, and no association was found between cardiac dose and LVEF in those treated with either VMAT or HT in early cardiac surveillance.

Comparison of organs at risk doses between deep inspiration breath-hold and free-breathing techniques during radiotherapy of left-sided breast cancer: A Meta-Analysis

After radiotherapy (RT) of left-sided breast cancer patients, organs at risk (OARs) such as heart, left anterior descending (LAD) coronary artery, and left lung could be affected by radiation dose in the long term. The objective of this study was to perform a comprehensive meta-analysis and determine OARs dose reduction during left-sided breast cancer treatment using different RT modalities combined with deep inspiration breath-hold (DIBH) relative to free-breathing (FB). PubMed, Scopus, EMBASE, ProQuest, Google Scholar, and Cochrane Library electronic databases were used to search for studies until June 6, 2021. Nineteen eligible studies were selected and analyzed using the RevMan 5.3 statistical software package. The pooled weighted mean difference (MD) with their 95% confidence intervals for each of the three OAR mean doses were determined using a random-effects meta-analysis model to assess the dose reductions. From a total of 189 studies, 1 prospective study, 15 retrospective studies, and 3 randomized control trials (RCTs) with an overall of 634 patients were included. Reduction of doses to the heart (weighted MD = -1.79 Gy; 95% CI (-2.28, -1.30); P = 0.00001), LAD (weighted MD = -8.34 Gy; 95% CI (-11.06, -5.61); P = 0.00001), and left-lung (weighted MD = -0.90 Gy; 95% CI (-1.19, -0.61); P = 0.00001) were observed using DIBH combinations relative to FB combination. This study emphasizes that during the treatment of left-sided breast/chest wall (CW) ± supraclavicular (SCV) ± infraclavicular (ICV) ± internal mammary chain (IMC) lymph nodes (LN) ± axillary (Ax)/ cancer patients, different RT modalities combined with DIBH techniques are better options to reduce dose to OARs compared to FB, which benefits to minimize the long-term complications.

Comparative Effectiveness Analysis of 3D-Conformal Radiation Therapy Versus Intensity Modulated Radiation Therapy (IMRT) in a Prospective Multicenter Cohort of Patients With Breast Cancer

PURPOSE

Simple intensity modulation of radiation therapy reduces acute toxicity compared with 2-dimensional techniques in adjuvant breast cancer treatment, but it remains unknown whether more complex or inverse-planned intensity modulated radiation therapy (IMRT) offers an advantage over forward-planned, 3-dimensional conformal radiation therapy (3DCRT).

METHODS AND MATERIALS

Using prospective data regarding patients receiving adjuvant whole breast radiation therapy without nodal irradiation at 23 institutions from 2011 to 2018, we compared the incidence of acute toxicity (moderate-severe pain or moist desquamation) in patients receiving 3DCRT versus IMRT (either inverse planned or, if forward-planned, using ≥5 segments per gantry angle). We evaluated associations between technique and toxicity using multivariable models with inverse-probability-of-treatment weighting, adjusting for treatment facility as a random effect.

RESULTS

Of 1185 patients treated with 3DCRT and conventional fractionation, 650 (54.9%) experienced acute toxicity; of 774 treated with highly segmented forward-planned IMRT, 458 (59.2%) did; and of 580 treated with inverse-planned IMRT, 245 (42.2%) did. Of 1296 patients treated with hypofractionation and 3DCRT, 432 (33.3%) experienced acute toxicity; of 709 treated with highly segmented forward-planned IMRT, 227 (32.0%) did; and of 623 treated with inverse-planned IMRT, 164 (26.3%) did. On multivariable analysis with inverse-probability-of-treatment weighting, the odds ratio for acute toxicity after inverse-planned IMRT versus 3DCRT was 0.64 (95% confidence interval, 0.45-0.91) with conventional fractionation and 0.41 (95% confidence interval, 0.26-0.65) with hypofractionation.

CONCLUSIONS

This large, prospective, multicenter comparative effectiveness study found a significant benefit from inverse-planned IMRT compared with 3DCRT in reducing acute toxicity of breast radiation therapy. Future research should identify the dosimetric differences that mediate this association and evaluate cost-effectiveness.

Optimization of Minimum Segment Width Parameter in the Intensity-Modulated Radiotherapy Plan for Esophageal Cancer

Purpose

This study was designed to explore the optimal minimum segment width (MSW) in the intensity-modulated radiotherapy (IMRT) plan for esophageal cancer.

Patients and Methods

The imaging data of 20 esophageal cancer patients were selected for this study. Four IMRT plans were designed for each patient with MSWs of 0.5, 1.0, 1.5, and 2.0 cm. The conformity index (CI) and homogeneity index (HI) of the planning target volumes (PTV), organs at risk (OARs), control points (CP), monitor units (MU), plan delivery time (DT), and gamma passing rates (GPR) were collected and compared to appraise the treatment plan quality and delivery efficiency.

Results

Lower-MSW plans had larger CI and smaller HI values, and lower dose parameters of OARs and PTVs. The HI, CI, and dose parameter of OARs in the 0.5 and 1.0 cm MSW groups were similar and much better than those of the 1.5 and 2.0 cm MSW groups. Meanwhile, the plan in the 0.5 cm MSW group had significantly higher MUs, CPs, and DTs, and a significantly lower relative dose of GPR with a 3% dose difference and 3 mm distance to agreement criteria than the other three groups.

Conclusion

The 0.5 and 1 cm MSW groups had better dosimetric parameters and IMRT plan quality than the other groups. However, plans with 0.5 cm MSW had worse delivery accuracy and efficiency than the other three groups. Thus, MSW of 1.0 cm was the optimal choice to ensure good quality, delivery accuracy, and treatment efficiency in IMRT plans for esophageal cancer.

Combination of Modern Radiotherapy and New Targeted Treatments for Breast Cancer Management

Simple Summary

Since the introduction of hormone therapy for the treatment of breast cancer (BC) three decades ago, many new targeted therapies have been developed. Some of them are currently used, such as HER2 inhibitors, while others are still under development, such as cell cycle (CDK) inhibitors, immune checkpoint (PD1/PDL1) inhibitors, or molecules acting on DNA damage (PARP) repair. Besides this, radiation therapy (RT) is commonly used either as adjuvant treatment for early BC after breast conservative surgery or in palliative intent for the treatment of metastatic sites. Our research has shown that the combinations of the most commonly used targeted treatments and RT were feasible with a few toxicities. Nevertheless, most of the knowledge on this subject is based on retrospective studies and a small number of patients and care should be taken in this setting until these results would be confirmed in prospective randomized studies.

Abstract

Background: The objective of the present study was to review the essential knowledge about the combinations of the most commonly used or under development targeted treatments and radiation therapy (RT). Methods: Preclinical and clinical studies investigating this combination were extensively reviewed. Results: Several studies showed that the combination of RT and tamoxifen increased the risk of radiation-induced pulmonary toxicity; therefore, both modalities should not be given concomitantly. The combination of HER2 inhibitors (trastuzumab, pertuzumab) and RT seems to be safe. However, trastuzumab emtansine (T-DM1) should not be administered concurrently with brain RT since this combination could increase the risk of brain radionecrosis. The combination of RT and other new target treatments such as selective estrogen receptor degradants, lapatinib, cell cycle inhibitors, immune checkpoint inhibitors, or molecules acting on DNA damage repair seems feasible but was essentially evaluated on retrospective or prospective studies with a small number of patients. Furthermore, there is considerable heterogeneity among these studies regarding the dose and fractionation of radiation, the dosage of drugs, and the sequence of treatments used. Conclusions: The combination of RT with most targeted therapies for BC appears to be well-tolerated, but these results need to be confirmed in prospective randomized studies.

Hypofractionated radiotherapy in ten fractions for postmastectomy patients: a phase II study compared with another hypofractionation schedule with sixteen fractions

Background

The purpose of this phase II study was to evaluate the feasibility of hypofractionated radiotherapy (HFRT) with a dose of 36.5 Gy in 10 fractions in postmastectomy patients.

Methods

From March 2014 to December 2015, 85 patients with locally advanced breast cancer were eligible to participate in this study with a schedule of 36.5 Gy in 10 fractions. Intensity-modulated radiation therapy (IMRT) was delivered to the chest wall with or without the supraclavicular region. The primary endpoint was radiation-related toxicities. The secondary endpoints were locoregional failure-free survival (LRFFS), disease-free survival (DFS) and overall survival (OS). And the outcomes were compared with our retrospective study of 72 patients with 42.5 Gy in 16 fractions.

Results

The median follow-up was 69.0 (range 66.5-71.5) months in the 36.5 Gy group and 93.0 (range 91.9-94.1) months in the 42.5 Gy group, respectively. Radiation-related toxicities were mainly grade 1, although a few patients had grade 2 plexopathy (1.2%) and acute skin toxicity (1.2%) in the 36.5 Gy group, and grade 2 acute skin toxicity (5.6%) and lymphedema (4.2%) in the 42.5 Gy group. There were no significant differences between the groups in acute and late toxicities. For all the patients, the 5-year LRFFS, DFS and OS were 97.7 and 100.0%, 93.1 and 90.3%, 98.8 and 97.2%, respectively, without significant differences between the groups.

Conclusion

Postmastectomy HFRT with a schedule of 36.5 Gy in 10 fractions was feasible, with mild toxicities and excellent 5-year clinical outcome.

Trial registration

Trial registration number: ChiCTR-ONRC-14004391.

Date of registration: 9/3/2014.

Modern Rotational Radiation Techniques with Volumetric Modulated Arc Therapy or Helical Tomotherapy for Optimal Sparing of the Lung and Heart in Left-Breast Cancer Radiotherapy Plus Regional Nodal Irradiation: A Comparative Dosimetric Analysis

Simple Summary

For advanced left-breast cancer patients, adjuvant radiotherapy (RT) with regional nodal irradiation (RNI) has been indicated to reduce cancer recurrence and mortality. Modern arc RT techniques, volumetric-modulated arc therapy (VMAT), or helical tomotherapy (HT), can minimize normal organ exposure without compromising disease control. The aim of this study is to identify which arc technique is optimal for patients receiving left-breast RT with RNI, and to explore distinct RNI volumes with or without IMN. A total of 108 eligible patients were enrolled (70 VMAT, 38 HT). VMAT reduced the mean dose and low-dose exposure to the heart, ipsilateral lung, whole lung, contralateral breast, and esophagus compared with HT. The advantage of VMAT for normal organ sparing was distinct when performing RNI with IMN irradiation. To limit normal organ exposure and reduce potential toxicities, VMAT is the optimal technique for patients with left-breast cancer who are undergoing RT with RNI.

Abstract

Background: For advanced breast cancer with lymph node involvement, adjuvant radiotherapy (RT) with regional nodal irradiation (RNI) has been indicated to reduce cancer recurrence and mortality. However, an extensive RT volume is associated with normal organ exposure, which increases the toxicity and affects patient outcomes. Modern arc RT techniques can improve normal organ sparing compared with conventional techniques. The aim of this study was to explore the optimal technique for left-breast RT with RNI. Methods: We retrospectively reviewed patients receiving RT with RNI for left-breast cancer. We used modern arc RT techniques with either volumetric-modulated arc therapy (VMAT) or helical tomotherapy (HT) with a novel block technique, and compared differences in dosimetry parameters between the two groups. Subgroup analysis of RNI with or without internal mammary node (IMN) volume was also performed. Results: A total of 108 eligible patients were enrolled between 2017 and 2020, of whom 70 received VMAT and 38 received HT. The median RT dose was 55 Gy. No significant differences were found regarding the surgery, RT dose, number of fractions, target volume, and RNI volume between the VMAT and HT groups. VMAT reduced the heart mean dose more than HT (3.82 vs. 5.13 Gy, p < 0.001), as well as the cardiac parameters of V5–V20, whole-lung mean dose, lung parameters of V5–V20, and contralateral-breast and esophagus mean dose. In the subgroup analysis of RNI with IMNs, the advantage of VMAT persisted in protecting the heart, lung, contralateral breast, and esophagus. HT was beneficial for lowering the thyroid mean dose. For RNI without IMN, VMAT improved the low-dose exposure of the heart and lung, but HT was similar to VMAT in terms of heart, whole-lung, and contralateral-breast mean dose. Conclusions: For patients with left-breast cancer receiving adjuvant RT with RNI, VMAT reduced the exposure dose to the heart, lung, contralateral breast, and esophagus compared with HT. VMAT was superior to HT in terms of normal organ sparing in the patients who underwent RNI with IMN irradiation. Considering the reduction in normal organ exposure and potential toxicity, VMAT is the optimal technique for patients receiving RNI when deep inspiration breath-hold is not available.

Racial and Ethnic Disparities in Rates of Invasive Second Breast Cancer Among Women With Ductal Carcinoma In Situ in Hawai'i

Importance

Women with ductal carcinoma in situ (DCIS) may develop a subsequent invasive second breast cancer (SBC). Understanding the association of racial and ethnic factors with the development of invasive SBC may help reduce overtreatment and undertreatment of women from minority groups.

Objective

To evaluate risk factors associated with developing invasive ipsilateral SBC (iiSBC) and invasive contralateral SBC (icSBC) among women with an initial diagnosis of DCIS who are from racial and ethnic minority populations.

Design, Setting, and Participants

This retrospective cohort study used deidentified data from the Hawai'i Tumor Registry of 6221 female Hawai'i residents aged 20 years or older who received a diagnosis of DCIS between January 1, 1973, and December 31, 2017. The 5 most populous ethnic groups were compared (Chinese, Filipino, Japanese, Native Hawaiian, and White). Data analysis was performed from 2020 to 2021.

Exposures

Patient demographic and clinical characteristics and the first course of treatment.

Main Outcome and Measures

The a priori study outcome was the development of invasive SBC. Logistic regression was used to identify factors associated with invasive SBC. Factors that were significant on unadjusted analyses were included in the adjusted models (ie, age, race and ethnicity, diagnosis year, DCIS histologic characteristics, laterality, hormone status, and treatment).

Results

The racial and ethnic distribution of patients with DCIS across the state's most populous groups were 2270 Japanese women (37%), 1411 White women (23%), 840 Filipino women (14%), 821 Native Hawaiian women (13%), and 491 Chinese women (8%). Women of other minority race and ethnicity collectively comprised 6% of cases (n = 388). A total of 6221 women (age range, 20 to ≥80 years) were included in the study; 4817 (77%) were 50 years of age or older, 4452 (72%) received a diagnosis between 2000 and 2017, 2581 (42%) had well or moderately differentiated histologic characteristics, 2383 (38%) had noninfiltrating intraductal DCIS, and 2011 (32%) were treated with mastectomy only. Of these 6221 women, 444 (7%) developed invasive SBC; 190 developed iiSBC (median time to SBC diagnosis, 7.8 years [range, 0.5-30 years]) and 254 developed icSBC (median time to SBC diagnosis, 5.9 years [range, 0.5-28.8 years]). On adjusted analysis, women who developed iiSBC were more likely to be younger than 50 years (adjusted odds ratio [aOR], 1.49; 95% CI, 1.08-2.06), Native Hawaiian (aOR, 3.28; 95% CI, 2.01-5.35), Filipino (aOR, 1.94; 95% CI, 1.11-3.42), Japanese (aOR, 1.58; 95% CI, 1.01-2.48), and untreated (aOR, 2.29; 95% CI, 1.09-4.80). Compared with breast-conserving surgery (BCS) alone, there was a decreased likelihood of iiSBC among women receiving BCS and radiotherapy (aOR, 0.45; 95% CI, 0.27-0.75), BCS and systemic treatment with or without radiotherapy (aOR, 0.40; 95% CI, 0.23-0.69), mastectomy only (aOR, 0.23; 95% CI, 0.13-0.39), and mastectomy and systemic treatment (aOR, 0.57; 95% CI, 0.33-0.96). Women who developed an icSBC were more likely to be Native Hawaiian (aOR, 1.69; 95% CI, 1.10-2.61) or Filipino (aOR, 1.70; 95% CI, 1.10-2.63). Risk of both iiSBC and icSBC decreased in the later years of diagnosis (2000-2017) compared with the earlier years (1973-1999).

Conclusions and Relevance

This study suggests that Native Hawaiian and Filipino women who initially received a diagnosis of DCIS were more likely to subsequently develop both iiSBC and icSBC. Japanese women and younger women were more likely to develop iiSBC. Subpopulation disaggregation may help guide clinical treatment and screening decisions for at-risk subpopulations.

The cardiac toxicity of radiotherapy - a review of characteristics, mechanisms, diagnosis, and prevention

PURPOSE

Radiation-induced heart disease (RIHD) is one of the most serious complications of radiotherapy. The purpose of this paper is to review recent researches about cardiac toxicity of radiotherapy in clinical characteristics, mechanisms, diagnosis, and prevention.

CONCLUSIONS

Powered by the rapid development of medicine, the overall survival (OS) of cancer has been improved significantly. Surgery, chemotherapy, and radiotherapy (RT) are three critical ways in the comprehensive treatments of cancer. There is a consensus that early diagnosis and interventions for the prevention of RIHD are crucial. This review concludes recent clinical and experimental studies on RIHD. RIHD, a heterogeneous and serious disease, is a spectrum of heart disease including myocardial disease, pericarditis, coronary artery disease, valvular heart disease, and conduction system dysfunction. Mean heart dose, biomarkers, and detecting techniques are important components in detecting heart injury. Improvements in radiotherapy regimens remain the primary goal of prevention. Further investigation is needed beyond the observation period of most of these studies.

Immobilization-assisted abdominal deep inspiration breath-hold in post-mastectomy radiotherapy of left-sided breast cancer with internal mammary chain coverage

Background

Whether to prophylactically irradiate the ipsilateral internal mammary chain (IMC) in post-mastectomy radiotherapy (PMRT) remains controversial because of equivocal clinical benefits against the added toxicities. Our previous study revealed that the cardiac dose was decreased during left-sided breast radiotherapy with abdominal deep inspiration breath-hold (aDIBH) as compared with free-breathing (FB) and thoracic deep inspiration breath-hold (tDIBH). Here we present the dosimetric advantage of aDIBH for patients undergoing PMRT with IMC coverage.

Methods

We prospectively analyzed 19 patients with left-sided breast cancer who underwent PMRT. Patients underwent computed tomography (CT) simulation under both free-breathing (FB) and aDIBH. The heart, left anterior descending coronary artery (LAD), lungs, and the contralateral breast was defined as organs at risk (OARs). Three-dimensional conformal radiation therapy (3D-CRT), inverse planning intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) were used to calculate the doses received by both the planning target volume (PTV) and OARs, which were compared using the Wilcoxon signed-rank test.

Results

Compared with FB, the D_mean of the heart and LAD were respectively reduced by 3.5 Gy (P<0.003) and 8.9 Gy (P<0.001) in 3D-CRT, 2.6 Gy (P<0.001), and 7.8 Gy (P=0.001) in IMRT, 1.5 Gy (P<0.001) and 4.5 Gy (P=0.001) in VMAT plans under aDIBH. Among all these plans, the D_mean of the heart was lowest in aDIBH _IMRT and 1.3 Gy lower than in aDIBH _VMAT (P=0.002). aDIBH _IMRT also resulted in a significantly reduced dose to the ipsilateral lung than plans under FB (P<0.05). D_mean and V5 to the contralateral lung and breast were higher in VMAT plans (P<0.05).

Conclusions

Using an immobilization-assisted aDIBH technique, radiation doses to the heart can be kept at reasonably low levels even if IMC is included in the clinical target volume (CTV). Among 3D-CRT, IMRT, and VMAT plans, IMRT plus aDIBH results in the best heart-sparing effect. We recommend that the aDIBH technique be routinely applied in suitable patients if the IMC is irradiated.

Prognostic value of the 21-gene recurrence score for regional recurrence in patients with estrogen receptor-positive breast cancer

PURPOSE

To evaluate the prognostic value of the 21-gene recurrence score (RS) for regional recurrence (RR) in patients with estrogen receptor-positive breast cancer.

METHODS

We reviewed the medical records of 446 patients who underwent 21-gene RS assay after breast-conserving surgery or mastectomy. The high-RS group was defined as patients who were (1) older than 50 years with an RS of 26 or higher, or (2) 50 years or younger with an RS of 16 or higher.

RESULTS

The 5-year rates of local recurrence (LR), RR, and distant metastasis (DM) were 2.2%, 2.7%, and 4.7%, respectively. The 5-year overall survival (OS) rate was 99.1%. Of the patients, 269 (60.3%) had low-RS, while 177 (39.7%) had high-RS. The 5-year OS rate of the high-RS group was significantly lower than that of the low-RS. The 5-year rates of RR and DM in the high-RS group were significantly higher than those in the low-RS group, while the LR rates did not differ significantly. In multivariable analysis, the high-RS group had a significant relationship with increased RR rate (p = 0.037). Patients who had both high-RS and clinical high-risk features had a significantly higher 5-year RR rate (7.9%) compared with other groups.

CONCLUSIONS

High-RS was an independent risk factor for RR. The significantly higher RR rate of patients with both high-RS and clinical high-risk features compared with other groups suggests that this patient group can be a potential candidate for regional nodal irradiation.

Analysis of Radiation Dose to the Shoulder by Treatment Technique and Correlation With Patient Reported Outcomes in Patients Receiving Regional Nodal Irradiation

Background/Purpose

Shoulder/arm morbidity is a late complication of breast cancer treatment with surgery and regional nodal irradiation (RNI). We set to analyze the impact of radiation technique [intensity modulated radiation therapy (IMRT) or 3D conformal radiation therapy (3DCRT)] on radiation dose to the shoulder with a hypothesis that IMRT use results in smaller volume of shoulder receiving radiation. We explored the relationship of treatment technique on long-term patient-reported outcomes using the quick disabilities of the arm, shoulder, and hand (q-DASH) questionnaire.

Materials/Methods

We identified patients treated with adjuvant RNI (50 Gy/25 fractions) from 2013 to 2018. We retrospectively contoured the shoulder organ-at-risk (OAR) from 2 cm above the ipsilateral supraclavicular (SCL) planning target volume (PTV) to the inferior SCL PTV slice and calculated the absolute volume of shoulder OAR receiving 5–50 Gy (V5–V50). We identified patients that completed a q-DASH questionnaire ≥6 months from the end of RNI.

Results

We included 410 RNI patients: 54% stage III, 72% mastectomy, 35% treated with IMRT. IMRT resulted in significant reductions in the shoulder OAR volume receiving 20–50 Gy vs. 3DCRT. In total, 82 patients completed the q-DASH. The mean (SD) q-DASH=25.4 (19.1) and tended to be lower with IMRT vs. 3DCRT: 19.6 (16.4) vs. 27.8 (19.8), p=0.078.

Conclusion

We found that IMRT reduces radiation dose to the shoulder and is associated with a trend toward reduced q-DASH scores ≥6 months post-RNI in a subset of our cohort. These results support prospective evaluation of IMRT as a technique to reduce shoulder morbidity in breast cancer patients receiving RNI.

Intensity Modulated Radiation Therapy (IMRT) With Simultaneously Integrated Boost Shortens Treatment Time and Is Noninferior to Conventional Radiation Therapy Followed by Sequential Boost in Adjuvant Breast Cancer Treatment: Results of a Large Randomized Phase III Trial (IMRT-MC2 Trial)

PURPOSE

In the modern era, improvements in radiation therapy techniques have paved the way for simultaneous integrated boost irradiation in adjuvant breast radiation therapy after breast conservation surgery. Nevertheless, randomized trials supporting the noninferiority of this treatment to historical standards of care approach are lacking.

METHODS

A prospective, multicenter, randomized phase 3 trial (NCT01322854) was performed to analyze noninferiority of conventional fractionated intensity modulated radiation therapy with simultaneous integrated boost (IMRT-SIB) to 3-D conformal radiation therapy with sequential boost (3-D-CRT-seqB) for breast cancer patients. Primary outcomes were local control (LC) rates at 2 and 5 years (noninferiority margin at hazard ratio [HR] of 3.5) as well as cosmetic results 6 weeks and 2 years after radiation therapy (evaluated via photo documentation calculating the relative breast retraction assessment [pBRA] score [noninferiority margin of 1.25]).

RESULTS

A total of 502 patients were randomly assigned from 2011 to 2015. After a median follow-up of 5.1 years, the 2-year LC for the IMRT-SIB arm was noninferior to the 3-D-CRT-seqB arm (99.6% vs 99.6%, respectively; HR, 0.602; 95% CI, 0.123-2.452; P = .487). In addition, noninferiority was also shown for cosmesis after IMRT-SIB and 3-D-CRT-seqB at both 6 weeks (median pBRA, 9.1% vs 9.1%) and 2 years (median pBRA, 10.4% vs 9.8%) after radiation therapy (95% CI, -0.317 to 0.107 %; P = .332). Cosmetic assessment according to the Harvard scale by both the patient and the treating physician as well as late-toxicity evaluation with the late effects normal tissues- subjective, objective, management, analytic criteria, a score for the evaluation of long-term adverse effects in normal tissue, revealed no significant differences between treatment arms. In addition, there was no difference in overall survival rates (99.6% vs 99.6%; HR, 3.281; 95% CI: -0.748 to 22.585; P = .148) for IMRT-SIB and 3-D-CRT-seqB, respectively.

CONCLUSIONS

To our knowledge, this is the first prospective trial reporting the noninferiority of IMRT-SIB versus 3-D-CRT-seqB with respect to cosmesis and LC at 2 years of follow-up. This treatment regimen considerably shortens adjuvant radiation therapy times without compromising clinical outcomes.

Patient Perceptions in a Nonblinded Randomized Trial of Radiation Therapy Technologies: A Novel Survey Study Exploring Therapeutic Misconception

PURPOSE

Therapeutic misconception is the tendency for a clinical trial participant to overlook the scientific objective of a clinical trial and instead believe that an experimental intervention is intended for personal therapeutic benefit. We sought to evaluate this tendency in the setting of a clinical trial of a new radiation therapy technology.

METHODS

Patients with left-sided, node positive breast cancer enrolled in a randomized clinical trial evaluating intensity modulated radiation therapy with deep inspiration breath hold (IMRT-DIBH) versus 3-dimensional conformal radiation therapy (3DCRT). Patients who enrolled completed surveys at baseline, after randomization, and upon completion of radiation therapy to evaluate expectations, satisfaction, and experiences.

RESULTS

Forty women participated in the survey study, with 20 in each arm. Most participants endorsed the perception that participation in the trial might result in better treatment than the current standard treatment (77%) and more medical attention than being off trial (54%). At baseline, most women (74%) believed that a new treatment technology is superior than an established one. Before randomization, 43% of participants believed IMRT-DIBH would be more effective than standard treatment with 3DCRT, none believed that 3DCRT would be more effective, 23% believed that they would be the same, and 34% did not know. None believed that IMRT-DIBH would cause worse long-term side effects, whereas 37% thought that 3DCRT would. Most (71%) reported that they would choose to be treated with IMRT-DIBH; none would have elected 3DCRT if given a choice. Nearly half (44%) in the 3DCRT arm wished that they had been assigned to the IMRT-DIBH arm; none in the IMRT-DIBH arm expressed a wish for crossover.

CONCLUSIONS

Most participants reported the perception that trial participation would result in better treatment and more medical attention than off trial, hallmarks of therapeutic misconception. Our observations provide empirical evidence of a fixed belief in the superiority of new technology and highlight the importance of adjusting expectations through informed consent to mitigate therapeutic misconception.

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

BACKGROUND/PURPOSE

Rates of acute esophagitis in breast cancer patients undergoing regional nodal irradiation (RNI) are under-reported. We set to identify esophageal dose-volume constraints associated with grade 2 esophagitis (G2E). We hypothesized that the G2E rate was higher with intensity modulated radiation therapy (IMRT) vs. 3D conformal radiation therapy (3DCRT).

MATERIALS/METHODS

We identified patients that received RNI (50 Gy/25 fractions) from 1/2013 to 6/2019. We retrospectively contoured the esophagus in a consistent manner and recorded esophageal mean dose, max dose, and V10-V50. Our primary endpoint was the G2E rate. Receiver operating characteristics curves analysis (e.g., Youden's J statistic) were used to determine the cutpoints for the dosimetric parameters which were then tested in logistic regression models.

RESULTS

We identified 531 patients (50% left-sided; 41% IMRT; 16.2% G2E). G2E was significantly higher in IMRT vs. 3DCRT patients (23.6% vs. 10.9%, p < 0.0001). All esophageal dosimetric parameters were significantly associated with G2E after adjusting for age and laterality. The cutpoints for esophageal mean dose, V10 and V20 were 11 Gy, 30%, and 15%, respectively. The associations between the dichotomized dose-volume parameters and G2E were OR = 3.82 (95% CI 2.28-6.40, p < 0.0001) for esophageal mean dose, OR = 5.37 (95% CI 3.01-9.58, p < 0.0001) for esophageal V10, and OR = 3.23 (95% CI 1.93-5.41, p < 0.0001) for esophageal V20.

CONCLUSION

In patients receiving RNI with modern techniques, we found that G2E occurs in >15%, and more frequently with IMRT. These data strongly support the routine contouring of the esophagus in RNI planning, and our constraints should be incorporated in future prospective protocols of RNI.

Assessing the Need for Adjusted Organ-at-Risk Planning Goals for Patients Undergoing Adjuvant Radiation Therapy for Locally Advanced Breast Cancer with Proton Radiation

PURPOSE

Locally advanced breast cancer requires surgical management via lumpectomy or mastectomy with or without systemic therapy followed by chest wall or breast (CW) and comprehensive nodal irradiation (CNI). Radiation (RT) dose constraints for the heart and ipsilateral lung have been developed based on photon RT. Proton therapy (PBT) can deliver significantly lower doses of RT to these organs-at-risk (OARs) and may warrant adjustments to OAR planning goals.

METHODS AND MATERIALS

The RT plans of consecutive patients undergoing adjuvant CW-CNI RT with PBT within a single center were reviewed. A inital treatment volume, comprised of CW/intact breast + CNI (CTV_init) structure, including the CW and CNI but excluding any boost plans was analyzed. Frequency distributions were generated based on doses received by the heart, lungs, and esophagus for validated dosimetric parameters. Frequency distributions were generated and then stratified by laterality and compared using the Kruskal-Wallis H test. The 75th, 85th, and 95th percentiles for each dosimetric parameter were calculated, overall and by laterality. The 75th percentile (Q3), was used as a suggested primary goal, and the 95th percentile was used as a suggested secondary goal.

RESULTS

One hundred and seventy-two plans were analyzed. Forty-nine plans were right-sided, 107 were left-sided, and 16 were bilateral. The overall Q3 of the mean and V25 of the heart were 1.5 Gy and 1.7%, respectively. The mean and V25 to the heart differed significantly by laterality. Pulmonary values were similar to current recommendations. For all lateralites, the median volume of the esophagus receiving 70% prescription dose was ≤1 cm³.

CONCLUSIONS

We present the first dosimetric study providing complete OAR dose-volume histograms data for patients undergoing adjuvant pencil-beam scanning-PBT for locally advanced breast cancer, with detailed information on central tendencies, ranges and distributions of data. We have provided suggested planning goals and metrics for the lungs, heart, and esophagus; the latter 2 differing significantly from current Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) constraints and classical photon goals.

Reducing Heart Dose with Protons and Cardiac Substructure Sparing for Mediastinal Lymphoma Treatment

Purpose

Electrocardiogram-gated computed tomography with coronary angiography can be used for cardiac substructure sparing (CSS) optimization, which identifies and improves avoidance of cardiac substructures when treating with intensity modulated radiotherapy (IMRT). We investigated whether intensity modulated proton therapy (IMPT) would further reduce dose to cardiac substructures for patients with mediastinal lymphoma.

Patients and Methods

Twenty-one patients with mediastinal lymphoma were enrolled and underwent electrocardiogram-gated computed tomography angiography during or shortly after simulation for radiotherapy planning. Thirteen patients with delineated cardiac substructures underwent comparative planning with both IMPT and IMRT. Plans were normalized for equivalent (95%) target volume coverage for treatment comparison.

Results

Thirteen patients met criteria for this study. The median size of the mediastinal lymphadenopathy was 7.9 cm at the greatest diameter. Compared with IMRT-CSS, IMPT-CSS significantly reduced mean dose to all cardiac substructures, including 3 coronary arteries and 4 cardiac valves. Use of IMPT significantly reduced average whole-heart dose from 9.6 to 4.9 Gy (P < .0001), and average mean lung dose was 9.7 vs 5.8 Gy (P < .0001). Prospectively defined clinically meaningful improvement was observed in at least 1 coronary artery in 9 patients (69%), at least 1 cardiac valve in 10 patients (77%), and whole heart in all 13 patients.

Conclusions

For patients with mediastinal lymphoma, IMPT-CSS treatment planning significantly reduced radiation dose to cardiac substructures. The significant improvements outlined in this study for proton therapy suggest possible clinical improvement in alignment with previous analyses of CSS optimization.

No Difference in Overall Survival and Non-Breast Cancer Deaths after Partial Breast Radiotherapy Compared to Whole Breast Radiotherapy-A Meta-Analysis of Randomized Trials

Purpose/objective: Adjuvant radiotherapy after breast conserving surgery is the standard approach in early stage breast cancer. However, the extent of breast tissue that has to be targeted with radiation has not been determined yet. Traditionally, the whole breast was covered by two opposing tangential beams. Several randomized trials have tested partial breast irradiation (PBI) compared to whole breast irradiation (WBI) using different radiation techniques. There is evidence from randomized trials that PBI might result in lower mortality rates compared to WBI. We aimed to reassess this question using current data from randomized trials. Material/methods: We performed a systematic literature review searching for randomized trials comparing WBI and PBI in early stage breast cancer with publication dates after 2009. The meta-analysis was performed using the published event rates and the effect sizes for overall survival (OS), breast cancer-specific survival (BCSS), and non-breast cancer death (NBCD) as investigated endpoints. Analysis of subgroups using different radiation techniques was intended. We used hazard ratios (HR) and risk differences (RD) to estimate pooled effect sizes. Statistical analysis was performed using the inverse variance heterogeneity model. Results: We identified eleven studies randomizing between PBI and WBI. We did not find significant differences in OS (n = 14,070; HR = 1.02; CI-95%: 0.89–1.16; p = 0.810, and n = 15,203; RD = −0.001; CI-95%: −0.008–0.006; p = 0.785) and BCSS (n = 15,203; RD = 0.001; CI-95%: −0.002–0.005; p = 0.463). PBI also did not result in a significant decrease of NBCD (n = 15,203; RD = −0.003; CI-95%: −0.010–0.003; p = 0.349). A subgroup analysis by radiation technique also did not point to any detectable differences. Conclusion: In contrast to a previous assessment of mortality, we could not find a detrimental effect of WBI on OS or NBCD. A longer follow-up might be necessary to fully assess the long-term mortality effects of PBI compared to WBI.

Clinical Effectiveness of an Adaptive Treatment Planning Algorithm for Intensity Modulated Radiation Therapy Versus 3D Conformal Radiation Therapy for Node-Positive Breast Cancer Patients Undergoing Regional Nodal Irradiation/Postmastectomy Radiation Therapy

PURPOSE

Clinical trials support adjuvant regional nodal irradiation (RNI) after breast-conserving surgery or mastectomy for patients with lymph node-positive breast cancer. Advanced treatment planning techniques (eg, intensity modulated radiation therapy [IMRT]) can reduce dose to organs at risk (OARs) in this situation. However, uncertainty persists about when IMRT is clinically indicated (vs 3-dimensional conformal radiation therapy [3DCRT]) for RNI. We hypothesized that an adaptive treatment planning algorithm (TPA) for IMRT adoption would allow OAR constraints for RNI to be met when 3DCRT could not without significantly changing toxicity and locoregional recurrence (LRR) patterns.

METHODS AND MATERIALS

Since 2013, all RNI patients also underwent an adaptive TPA that began with 3DCRT and then changed to IMRT when OAR constraints (mean heart dose ≤500 cGy; ipsilateral lung V20 ≤35%) could not be met. Patients received 2 Gy/d to the prospectively contoured target volumes (including internal mammary nodes). We retrospectively evaluated the dosimetry and clinical outcomes of the treatment groups (IMRT vs 3DCRT). The primary endpoint was the cumulative incidence of LRR as the site of first recurrence, and we specifically address patterns of failure based on dose to the posterior supraclavicular nodal region (SCL-post).

RESULTS

Two hundred forty patients (60% stage III; mean 4.0 + nodes) underwent an adaptive-TPA for RNI after mastectomy (74%) or breast-conserving surgery (26%), resulting in 168 patients treated with 3DCRT and 72 patients treated with IMRT. There were 7 LRRs (2 IMRT, 5 3DCRT) resulting in 4-year LRR of 2.8% for IMRT versus 1.8% for 3DCRT (P = .99). Three patients (2 IMRT, 1 3DCRT) had SCL nodal failures (1 in the SCL-post).

CONCLUSIONS

An adaptive TPA for use of IMRT when 3DCRT does not meet critical OAR constraints resulted in rare high-grade toxicity and no difference in failure patterns between patients treated with IMRT and 3DCRT. These data should provide reassurance that IMRT maintains the therapeutic ratio by preserving cancer control outcomes without excess toxicity when 3DCRT fails to meet OAR constraints.

Helical tomotherapy with a complete-directional-complete block technique effectively reduces cardiac and lung dose for left-sided breast cancer

Objectives:

To evaluate the feasibility and optimal restricted angle of the complete-directional-complete block (CDCB) technique in helical tomotherapy (HT) by including regional nodal irradiation (RNI) with the internal mammary node (IMN) in left-sided breast cancer.

Methods:

Ten left-sided breast cancer patients treated with 50 Gy in 25 fractions were compared with five-field intensity-modulated radiation therapy (5F-IMRT) and six types of HT plans. In the HT plans, complete block (CB), organ-based directional block (OBDB) and CDCB with different restricted angles were used.

Results:

The conformity index (CI) between the CDCB_0,10,15,20 and 5F-IMRT groups was similar. Compared to CB, OBDB and 5F-IMRT, CDCB₂₀ resulted in a decreased ipsilateral mean lung dose. The low-dose region (V₅) of the ipsilateral lung in OBDB (84.0%) was the highest among all techniques (p < 0.001). The mean dose of the heart in CB was significantly reduced (by 11.5–22.4%) compared with other techniques. The V₃₀ of the heart in CDCB₂₀ (1.9%) was significantly lower than that of CB, OBDB and 5F-IMRT. Compared to the mean dose of the left anterior descending (LAD) artery of 5F-IMRT (27.0 Gy), CDCB₀, CDCB₁₀, CDCB₁₅, CDCB₂₀ and OBDB reduced the mean dose effectively by 31.7%, 38.3%, 39.6%, 42.0 and 56.2%, respectively. Considering the parameters of the organs-at-risk (OARs), CDCB_10,15,20 had higher expectative values than the other techniques (p = 0.01).

Conclusions:

HT with the CDCB technique is feasible for treating left-sided breast cancer patients. The CDCB_10-20 techniques not only achieved similar planning target volume coverage, homogeneity and dose conformity but also allowed better sparing of the heart and bilateral lungs.

Advances in knowledge:

For left-sided breast cancer patients whose RNI field includes the IMN, heart avoidance is an important issue. The CDCB technique achieved good PTV coverage, homogeneity and dose conformity and allowed better sparing of the mean dose of the lung, the LAD artery, and the heart and reduced the V₃₀ of the heart.

Phase II Study of Proton Beam Radiation Therapy for Patients With Breast Cancer Requiring Regional Nodal Irradiation

PURPOSE

To evaluate the safety and efficacy of proton beam radiation therapy (RT) for patients with breast cancer who require regional nodal irradiation.

METHODS

Patients with nonmetastatic breast cancer who required postoperative RT to the breast/chest wall and regional lymphatics and who were considered suboptimal candidates for conventional RT were eligible. The primary end point was the incidence of grade 3 or higher radiation pneumonitis (RP) or any grade 4 toxicity within 3 months of RT. Secondary end points were 5-year locoregional failure, overall survival, and acute and late toxicities per Common Terminology Criteria for Adverse Events (version 4.0). Strain echocardiography and cardiac biomarkers were obtained before and after RT to assess early cardiac changes.

RESULTS

Seventy patients completed RT between 2011 and 2016. Median follow-up was 55 months (range, 17 to 82 months). Of 69 evaluable patients, median age was 45 years (range, 24 to 70 years). Sixty-three patients (91%) had left-sided breast cancer, two had bilateral breast cancer, and five had right-sided breast cancer. Sixty-five (94%) had stage II to III breast cancer. Sixty-eight (99%) received systemic chemotherapy. Fifty (72%) underwent immediate reconstruction. Median dose to the chest wall/breast was 49.7 Gy (relative biological effectiveness) and to the internal mammary nodes, 48.8 Gy (relative biological effectiveness), which indicates comprehensive coverage. Among 62 surviving patients, the 5-year rates for locoregional failure and overall survival were 1.5% and 91%, respectively. One patient developed grade 2 RP, and none developed grade 3 RP. No grade 4 toxicities occurred. The unplanned surgical re-intervention rate at 5 years was 33%. No significant changes in echocardiography or cardiac biomarkers after RT were found.

CONCLUSION

Proton beam RT for breast cancer has low toxicity rates and similar rates of disease control compared with historical data of conventional RT. No early cardiac changes were observed, which paves the way for randomized studies to compare proton beam RT with standard RT.

Intensity modulated radiation therapy following lumpectomy in early-stage breast cancer: Patterns of use and cost consequences among Medicare beneficiaries

Purpose

In 2013, the American Society for Radiation Oncology (ASTRO) issued a Choosing Wisely recommendation against the routine use of intensity modulated radiotherapy (IMRT) for whole breast irradiation. We evaluated IMRT use and subsequent impact on Medicare expenditure in the period immediately preceding this recommendation to provide a baseline measure of IMRT use and associated cost consequences.

Methods and materials

SEER records for women ≥66 years with first primary diagnosis of Stage I/II breast cancer (2008–2011) were linked with Medicare claims (2007–2012). Eligibility criteria included lumpectomy within 6 months of diagnosis and radiotherapy within 6 months of lumpectomy. We evaluated IMRT versus conventional radiotherapy (cRT) use overall and by SEER registry (12 sites). We used generalized estimating equations logit models to explore adjusted odds ratios (OR) for associations between clinical, sociodemographic, and health services characteristics and IMRT use. Mean costs were calculated from Medicare allowable costs in the year after diagnosis.

Results

Among 13,037 women, mean age was 74.4, 50.5% had left-sided breast cancer, and 19.8% received IMRT. IMRT use varied from 0% to 52% across SEER registries. In multivariable analysis, left-sided breast cancer (OR 1.75), living in a big metropolitan area (OR 2.39), living in a census tract with ≤$90,000 median income (OR 1.75), neutral or favorable local coverage determination (OR 3.86, 1.72, respectively), and free-standing treatment facility (OR 3.49) were associated with receipt of IMRT (p<0.001). Mean expenditure in the year after diagnosis was $8,499 greater (p<0.001) among women receiving IMRT versus cRT.

Conclusion

We found highly variable use of IMRT and higher expenditure in the year after diagnosis among women treated with IMRT (vs. cRT) with early-stage breast cancer and Medicare insurance. Our findings suggest a considerable opportunity to reduce treatment variation and cost of care while improving alignment between practice and clinical guidelines.

Technological evolution of radiation treatment: Implications for clinical applications

The contemporary approach to the management of a cancer patient requires an "ab initio" involvement of different medical domains in order to correctly design an individual patient's pathway toward cure. With new therapeutic tools in every medical field developing faster than ever before the patient care outcomes can be achieved if all surgical, drug, and radiation options are considered in the design of the appropriate therapeutic strategy for a given patient. Radiation therapy (RT) is a clinical discipline in which experts from different fields continuously interact in order to manage the multistep process of the radiation treatment. RT is found to be an appropriate intervention for diverse indications in about 50% of cancer patients during the course of their disease. Technologies are essential in dealing with the complexity of RT treatments and for driving the increasingly sophisticated RT approaches becoming available for the treatment of Cancer. High conformal techniques, namely intensity modulated or volumetric modulated arc techniques, ablative techniques (Stereotactic Radiotherapy and Stereotactic Radiosurgery), particle therapy (proton or carbon ion therapy) allow for success in treating irregularly shaped or critically located targets and for the sharpness of the dose fall-off outside the target. The advanced on-board imaging, including real-time position management systems, makes possible image-guided radiation treatment that results in substantial margin reduction and, in select cases, implementation of an adaptive approach. The therapeutic gains of modern RT are also due in part to the enhanced anticancer activity obtained by coadministering RT with chemotherapy, targeted molecules, and currently immune checkpoints inhibitors. These main clinically relevant steps forward in Radiation Oncology represent a change of gear in the field that may have a profound impact on the management of cancer patients.

Heart-sparing radiotherapy techniques in breast cancer patients: a recommendation of the breast cancer expert panel of the German society of radiation oncology (DEGRO)

PURPOSE

The aim of this review was to analyze the respective efficacy of various heart-sparing radiotherapy techniques.

MATERIAL AND METHODS

Heart-sparing can be performed in three different ways in breast cancer radiotherapy: by seeking to keep the heart out of treated volumes (i.e. by prone position or specific breathing techniques such as deep inspiration breath-hold [DIBH] and/or gating), by solely irradiating a small volume around the lumpectomy cavity (partial breast irradiation, PBI), or by using modern radiation techniques like intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT) or protons. This overview presents the available data on these three approaches.

RESULTS

Studies on prone position are heterogeneous and most trials only refer to patients with large breasts; therefore, no definitive conclusion can be drawn for clinical routine. Nonetheless, there seems to be a trend toward better sparing of the left anterior descending artery in supine position even for these selected patients. The data on the use of DIBH for heart-sparing in breast cancer patients is consistent and the benefit compared to free-breathing is supported by several studies. In comparison with whole breast irradiation (WBI), PBI has an advantage in reducing the heart dose. Of note, DIBH and PBI with multicatheter brachytherapy are similar with regard to the dose reduction to heart structures. WBI by IMRT/VMAT techniques without DIBH is not an effective strategy for heart-sparing in breast cancer patients with "standard" anatomy. A combination of DIBH and IMRT may be used for internal mammary radiotherapy.

CONCLUSION

Based on the available findings, the DEGRO breast cancer expert panel recommends the use of DIBH as the best heart-sparing technique. Nonetheless, depending on the treatment volume and localization, other techniques may be employed or combined with DIBH when appropriate.

Which target volume should be considered when irradiating the regional nodes in breast cancer? Results of a network-meta-analysis

Purpose/objective(s)

Radiation treatment to the regional nodes results in an improvement in survival in breast cancer according to a meta-analysis of randomized trials. However, different volumes were targeted in these studies: breast or chestwall only (WBI/CWI), inclusion of the medial supraclavicular region and axillary apex (MS + WBI/CWI) or additional inclusion of the internal mammary chain (IM + MS + WBI/CWI). The benefit of treating the medial supraclavicular region and axillary apex compared to tangential breast or chestwall irradiation only remains unclear.

Materials/methods

A literature search was conducted identifying trials for adjuvant radiation volumes in nodal irradiation after breast surgery and axillary treatment. Events and effect sizes were extracted from the publications for the endpoints of overall survival (OS), breast cancer-specific survival (BCSS), disease-free survival (DFS), distant metastasis-free survival (DMFS) and loco-regional control (LRC). A network meta-analysis was performed using MetaXL V5.3 with the inverse variance heterogeneity model.

Results

We found two randomized studies (n = 5836) comparing comprehensive nodal irradiation to sole breast treatment as well as one randomized (n = 1407) and one prospective cohort study (n = 3377) analysing the additional treatment of the internal mammary chain against sole local and supraclavicular and axillary apex radiation. Compared to WBI/CWI alone the treatment of IM + MS + WBI/CWI (HR = 0.88; CI:0.78-0.99; p = 0.036) results in improved OS unlike MS + WBI/CWI (HR = 0.99; CI:0.86-1.14; p = 0,89). These results are confirmed in BCSS: IM + MS + WBI/CWI (HR = 0.82; CI:0.72-0.92; p = 0.002) and MS + WBI/CWI (HR = 0.96; CI:0.79-1.18; p = 0.69). PFS is significantly improved with the treatment of MS + WBI/CWI (OR = 0.83; CI:0.71-0.97; p = 0.019). Both nodal treatment volumes improve LRC (MS + WBI/CWI OR = 0.74; CI:0.62-0.87; p = 0.004 and IM + MS + WBI/CWI OR = 0.60; CI:0.43-0.86; p < 0,001). Yet only the internal mammary nodes provide a benefit in DMFS (MS + WBI/CWI HR = 0.97; CI:0.81-1.16; p = 0.74 and IM + MS + WBI/CWI HR = 0.84; CI:0.75-0.94; p = 0.002).

Conclusion

Expanding the radiation field to the axillary apex and supraclavicular nodes after axillary node dissection reduced loco-regional recurrences without improvement in overall and cancer-specific survival. A prolongation in survival due to regional nodal irradiation is achieved when the internal mammary chain is included. This derives from a reduction in distant metastasis.