Long-term cardiac mortality after hypofractionated radiation therapy in breast cancer

Final analysis of a Multicenter Single-Arm Confirmatory Trial of hypofractionated whole breast irradiation after breast-conserving surgery in Japan: JCOG0906

OBJECTIVE

To evaluate the safety and efficacy of hypofractionated whole breast irradiation for Asian women after breast-conserving surgery. This is an updated report with 5-year follow-up.

METHODS AND MATERIALS

Asian women who had invasive breast cancer with clinical tumor size ≤3 cm, pN0-1c and negative inked margins were enrolled. Hypofractionated whole breast irradiation of 42.56 Gy/16 fractions was delivered, and boost irradiation of 10.64 Gy/4 fractions was added when the surgical margin was ≤5 mm. The primary endpoint was the proportion of grade ≥ 2 late adverse reactions within 3 years. Secondary endpoints included early adverse events, overall survival, disease-free survival, ipsilateral breast relapse-free survival, late adverse reactions and cosmetic outcome. Toxicities were evaluated using CTCAE ver3.0. Cosmetic outcomes were assessed using a 4-point scale and CTCAE ver3.0 for hyper/hypopigmentation, breast nipple/areolar deformity and breast volume/deformity.

RESULTS

Between February 2010 and August 2012, 312 patients were enrolled, and 306 received hypofractionated whole breast irradiation. Median follow-up was 70.5 (range 7.6-88.9) months. The proportion of grade ≥ 2 late adverse reactions within 3 years was 4.3% (90% confidence interval 2.5-6.7%). Grade 2 early adverse events occurred in 38 (12.4%); none had grade 3/4. Five-year overall survival, disease-free survival and ipsilateral breast relapse-free survival were 98.7, 95.4 and 98.0%, respectively. Of the 304 evaluable patients, 29 (9.5%; 95% confidence interval 6.5-13.4%) had grade 2/3 late adverse reactions; none had grade 4/5. At 5 years, 70/289 (24.2%) showed any worsening of breast cosmetic changes.

CONCLUSIONS

Hypofractionated whole breast irradiation is considered a standard treatment for Asian women with margin-negative invasive breast cancer after breast-conserving surgery.

Cardiac mortality after radiotherapy, chemotherapy and endocrine therapy for breast cancer: Cohort study of 2 million women from 57 cancer registries in 22 countries

Comparisons of patients receiving different cancer treatments reflect the effects of both treatment and patient selection. In breast cancer, however, if radiotherapy decisions are unrelated to laterality, comparisons of left-sided and right-sided cancers can demonstrate the causal effects of higher-versus-lower cardiac radiation dose. Cardiac mortality was analysed using individual patient data for 1,934,248 women with breast cancer in 22 countries. The median date of diagnosis was 1996 and the interquartile range was 1987-2002. A total of 1,018,505 women were recorded as irradiated, 223,077 as receiving chemotherapy, 317,619 as receiving endocrine therapy and 55,264 died of cardiac disease. Analyses were stratified by time since breast cancer diagnosis, age at diagnosis, calendar year of diagnosis and country. Patient-selection effects were evident for all three treatments. For radiotherapy, there was also evidence of selection according to laterality in women irradiated 1990 or later. In patients irradiated before 1990, there was no such selection and cardiac mortality was higher in left-sided than right-sided cancer (rate ratio [RR]: 1.13, 95% confidence interval 1.09-1.17). Left-versus-right cardiac mortality RRs were greater among younger women (1.46, 1.19, 1.20, 1.09 and 1.08 after cancer diagnoses at ages <40, 40-49, 50-59, 60-69 and 70+ years, 2ptrend =0.003). Left-versus-right RRs also increased with time since cancer diagnosis (1.03, 1.11, 1.19 and 1.21 during 0-4, 5-14, 15-24 and 25+ years, 2ptrend =0.002) while for women who also received chemotherapy, the left-versus-right RR was 1.42 (95% confidence interval 1.13-1.77), compared to 1.10 (1.05-1.16) for women who did not (2pdifference = 0.03). These results show that the relative increase in cardiac mortality from cardiac exposure during breast cancer radiotherapy given in the past was greater in younger women, lasted into the third decade after exposure and was greater when chemotherapy was also given.

Early Detection of Cardiovascular Changes After Radiotherapy for Breast Cancer: Protocol for a European Multicenter Prospective Cohort Study (MEDIRAD EARLY HEART Study)

Background

Breast cancer is the most common cancer among women, and radiotherapy plays a major role in its treatment. However, breast cancer radiotherapy can lead to incidental irradiation of the heart, resulting in an increased risk for a variety of heart diseases arising many years after radiotherapy. Therefore, identifying breast cancer patients at the highest risk for radiation-induced cardiac complications is crucial for developing strategies for primary and secondary prevention, which may contribute to healthy aging. There is still a need for precise knowledge on the relationship between radiation dose to specific cardiac structures and early subclinical cardiac changes and their occurrence over time that could finally lead to cardiac complications.

Objective

The MEDIRAD EARLY HEART study aims to identify and validate new cardiac imaging and circulating biomarkers of radiation-induced cardiovascular changes arising within first 2 years of breast cancer radiotherapy and to develop risk models integrating these biomarkers combined with precise dose metrics of cardiac structures based on three-dimensional dosimetry.

Methods

The EARLY HEART study is a multicenter, prospective cohort study in which 250 women treated for breast cancer and followed for 2 years after radiotherapy will be included. Women treated with radiotherapy without chemotherapy for a unilateral breast cancer and aged 40-75 years meet the inclusion criteria. Baseline and follow-up data include cardiac measurements based on two-dimensional speckle-tracking echocardiography, computed tomography coronary angiography, cardiac magnetic resonance imaging, and a wide panel of circulating biomarkers of cardiac injury. The absorbed dose will be evaluated globally for the heart and different substructures. Furthermore, the dose-response relationship will allow modeling the radiation-induced occurrence and evolution of subclinical cardiac lesions and biomarkers to develop prediction models.

Results

This study details the protocol of the MEDIRAD EARLY HEART study and presents the main limits and advantages of this international project. The inclusion of patients began in 2017. Preliminary results are expected to be published in 2019, and complete analysis should be published in 2021.

Conclusions

The MEDIRAD EARLY HEART study will allow identifying the main cardiac imaging and blood-based determinants of radiation-induced cardiac injuries to better propose primary and secondary preventive measures in order to contribute to enhanced patient care and quality of life.

Trial Registration

ClinicalTrials.gov NCT03297346; https://clinicaltrials.gov/ct2/show/NCT03297346 (Archived by WebCite at http://www.webcitation.org/72KS7MIUU)

Registered Report Identifier

RR1-10.2196/9906

Impact of Ionizing Radiation on the Cardiovascular System: A Review

Radiation therapy has become one of the main forms of treatment for various types of cancers. Cancer patients previously treated with high doses of radiation are at a greater risk to develop cardiovascular complications later in life. The heart can receive varying doses of radiation depending on the type of therapy and can even reach doses in the range of 17 Gy. Multiple studies have highlighted the role of oxidative stress and inflammation in radiation-induced cardiovascular damage. Doses of ionizing radiation below 200 mGy, however, have been shown to have beneficial effects in some experimental models of radiation-induced damage, but low-dose effects in the heart is still debated. Low-dose radiation may promote heart health and reduce damage from oxidative stress and inflammation, however there are few studies focusing on the impact of low-dose radiation on the heart. In this review, we summarize recent studies from animal models and human data focusing on the effects and mechanism(s) of action of radiation-induced damage to the heart, as well as the effects of high and low doses of radiation and dose rates.

Long-Term Cardiovascular Risk After Radiotherapy in Women With Breast Cancer

Background

Radiotherapy for breast cancer often involves some incidental exposure of the heart to ionizing radiation. The effect of this exposure on the subsequent risk of heart disease is uncertain. We performed a meta‐analysis to investigate the link between radiotherapy and long‐term cardiovascular morbidity and mortality in patients with breast cancer.

Methods and Results

We performed a literature search using MEDLINE (January 1966 to January 2015) and EMBASE (January 1980 to January 2015) with no restrictions. Studies that reported relative risk (RR) estimates with 95%CIs for the associations of interest were included. Pooled effect estimates were obtained by using random‐effects meta‐analysis. Thirty‐nine studies involving 1 191 371 participants were identified. Patients who received left‐sided radiotherapy, as compared with those receiving right‐sided radiotherapy, experienced increased risks of developing coronary heart disease (RR 1.29, 95%CI 1.13‐1.48), cardiac death (RR 1.22, 95%CI 1.08‐1.37) and death from any cause (RR 1.05, 95%CI 1.01‐1.10). In a comparison of patients with radiotherapy and without radiotherapy, the RRs were 1.30 (95%CI 1.13‐1.49) for coronary heart disease and 1.38 (95%CI 1.18‐1.62) for cardiac mortality. Radiotherapy for breast cancer was associated with an absolute risk increase of 76.4 (95%CI 36.8‐130.5) cases of coronary heart disease and 125.5 (95%CI 98.8‐157.9) cases of cardiac death per 100 000 person‐years. The risk started to increase within the first decade for coronary heart disease and from the second decade for cardiac mortality.

Conclusions

Exposure of the heart to ionizing radiation during radiotherapy for breast cancer increases the subsequent risk of coronary heart disease and cardiac mortality.

Advanced Imaging and Receipt of Guideline Concordant Care in Women with Early Stage Breast Cancer

Objective. It is unknown whether advanced imaging (AI) is associated with higher quality breast cancer (BC) care. Materials and Methods. Claims and Surveillance Epidemiology and End Results data were linked for women diagnosed with incident stage I-III BC between 2002 and 2008 in western Washington State. We examined receipt of preoperative breast magnetic resonance imaging (MRI) or AI (defined as computed tomography [CT]/positron emission tomography [PET]/PET/CT) versus mammogram and/or ultrasound (M-US) alone and receipt of guideline concordant care (GCC) using multivariable logistic regression. Results. Of 5247 women, 67% received M-US, 23% MRI, 8% CT, and 3% PET/PET-CT. In 2002, 5% received MRI and 5% AI compared to 45% and 12%, respectively, in 2008. 79% received GCC, but GCC declined over time and was associated with younger age, urban residence, less comorbidity, shorter time from diagnosis to surgery, and earlier year of diagnosis. Breast MRI was associated with GCC for lumpectomy plus radiation therapy (RT) (OR 1.55, 95% CI 1.08-2.26, and p = 0.02) and AI was associated with GCC for adjuvant chemotherapy for estrogen-receptor positive (ER+) BC (OR 1.74, 95% CI 1.17-2.59, and p = 0.01). Conclusion. GCC was associated with prior receipt of breast MRI and AI for lumpectomy plus RT and adjuvant chemotherapy for ER+ BC, respectively.

A Study on Dosimetric Outcomes and Acute Toxicity of Post Mastectomy Adjuvant Hypofractionated Radiotherapy for Breast Cancer

INTRODUCTION

Hypofractionated External Beam Radiotherapy (HFRT) is a relatively new adjuvant Radiotherapy (RT) schedule for breast cancers following breast conservation surgery and less commonly, following mastectomy. Here we report our experience on normal tissue exposure and acute toxicity of HFRT after mastectomy.

AIM

To assess the dosimetric outcomes and acute toxicity profile of adjuvant HFRT following mastectomy for breast cancer.

MATERIALS AND MATERIALS

This prospective observational study considered consecutive patients planned for adjuvant HFRT (42.5 Gy in 16 sessions delivered over 3 weeks) to the chest wall with/without regional nodes between October 2014 and June 2015. The dosimetric parameters including dose homogeneity to the target volume and exposure to heart and lung were analyzed. Acute haematological and dermatological toxicity was recorded until upto three months after completion of RT.

RESULTS

Among the 56 patients treated with HFRT, the mean age was 49 years (range: 28-69 years). Pathologically positive nodes and ≥pT3 primary was observed in 44 (78.6%) and 12 (21.4%) patients, respectively. Majority (87.5%) received prior adjunct chemotherapy. RT to the supraclavicular fossa was delivered for 39 (69.6%) patients. The mean V90 and V95 to the Planning Target Volume (PTV) were 95% (± 3.3%) and 93% (± 4%), respectively. The maximum dose received was on average 47.7 Gy (112%; range: 46.2-48.5 Gy). The mean lung dose was 10.2 Gy (± 3.5 Gy) and V20 was 20.9% (± 6%). The mean V25 to heart was 6.6% (± 4.8%) for left sided and 0% for right sided tumours (p=0.001). Acute skin toxicity peaked at completion of RT and was tolerable (grade 0, I, II and III reactions were 75%, 16% and 1.8%, respectively). No patient had ≥ grade III haematological toxicity, and treatment was not interrupted for any patient.

CONCLUSION

Adjuvant HFRT could be planned while meeting the dose constraints to normal tissues in all patients and was well tolerated, with mild to moderate acute adverse effects that did not warrant any therapeutic intervention or treatment interruption.

Radiotherapy beyond cancer: target localization in real-time MRI and treatment planning for cardiac radiosurgery

PURPOSE

Atrial fibrillation (AFib) is the most common cardiac arrhythmia that affects millions of patients world-wide. AFib is usually treated with minimally invasive, time consuming catheter ablation techniques. While recently noninvasive radiosurgery to the pulmonary vein antrum (PVA) in the left atrium has been proposed for AFib treatment, precise target location during treatment is challenging due to complex respiratory and cardiac motion. A MRI linear accelerator (MRI-Linac) could solve the problems of motion tracking and compensation using real-time image guidance. In this study, the authors quantified target motion ranges on cardiac magnetic resonance imaging (MRI) and analyzed the dosimetric benefits of margin reduction assuming real-time motion compensation was applied.

METHODS

For the imaging study, six human subjects underwent real-time cardiac MRI under free breathing. The target motion was analyzed retrospectively using a template matching algorithm. The planning study was conducted on a CT of an AFib patient with a centrally located esophagus undergoing catheter ablation, representing an ideal case for cardiac radiosurgery. The target definition was similar to the ablation lesions at the PVA created during catheter treatment. Safety margins of 0 mm (perfect tracking) to 8 mm (untracked respiratory motion) were added to the target, defining the planning target volume (PTV). For each margin, a 30 Gy single fraction IMRT plan was generated. Additionally, the influence of 1 and 3 T magnetic fields on the treatment beam delivery was simulated using Monte Carlo calculations to determine the dosimetric impact of MRI guidance for two different Linac positions.

RESULTS

Real-time cardiac MRI showed mean respiratory target motion of 10.2 mm (superior-inferior), 2.4 mm (anterior-posterior), and 2 mm (left-right). The planning study showed that increasing safety margins to encompass untracked respiratory motion leads to overlapping structures even in the ideal scenario, compromising either normal tissue dose constraints or PTV coverage. The magnetic field caused a slight increase in the PTV dose with the in-line MRI-Linac configuration.

CONCLUSIONS

The authors' results indicate that real-time tracking and motion compensation are mandatory for cardiac radiosurgery and MRI-guidance is feasible, opening the possibility of treating cardiac arrhythmia patients completely noninvasively.

Hypofractionated whole breast radiotherapy: current perspectives

Adjuvant radiotherapy (RT) is an important part of breast cancer management but the dose and fractionation schedules used are variable. A total of 50 Gy in 25 daily fractions delivered over 5 weeks is often considered the “standard” adjuvant RT prescription. Hypofractionated regimes such as 42.5 Gy in 16 daily fractions or 40 Gy in 15 daily fractions following breast-conserving surgery have proven to be equally effective and achieve similar or better cosmetic and normal tissue outcomes for both invasive and in situ diseases and when treating the regional nodes. Hypofractionation is more convenient for patients and less costly. However, certain patients at higher risk of RT late effects may benefit from a less intense, even more extended fractionation schedule. This review describes the indications for whole breast hypofractionated adjuvant RT for patients with breast cancer following breast-conserving surgery and proposes that hypofractionation should be the new “standard” for adjuvant breast cancer RT.

Radiotherapy of the Lymphatic Pathways in Early Breast Cancer

International guidelines reveal substantial differences regarding indications for regional nodal irradiation (RNI). Recently, several randomized studies provided new insights and these are discussed here. Patients with 1-3 positive nodes seem to profit from RNI compared to whole-breast (WBI) or chest-wall irradiation (CWI) alone, both with regard to locoregional control and disease-free survival. Irradiation of the regional lymphatics including axillary, supraclavicular and internal mammary nodes provided a small but significant survival benefit in recent randomized trials and 1 meta-analysis. Lymph node irradiation yields comparable tumor control in comparison to axillary lymph node dissection while reducing the rate of lymph edema. Data concerning the impact of 1-2 macroscopically affected sentinel nodes or microscopic metastases on prognosis are equivocal. Recent data suggest that the current restrictive use of RNI should be scrutinized, as the hazard-benefit relation appears to shift towards an improvement of outcome.

Acute histopathological responses of testicular tissues after different fractionated abdominal irradiation in rats

PURPOSE

To compare the effects of different fractionated doses of abdominal radiation therapy on acute histopathological responses of testicular tissues in rats.

METHODS

Thirty-three 3-week-old Wistar albino rats were randomized into 6 groups: group 1 (n = 5), control; group 2 (n = 4), hypofractionated total abdominal irradiation (TAI) of 6 Gy/1 fraction/day for 2 days; group 3 (n = 6), hypofractionated TAI of 4 Gy/1 fraction/day for 3 days; group 4 (n = 6), hypofractionated TAI of 3 Gy/1 fraction/day for 4 days; group 5 (n = 6), conventionally fractionated TAI of 2 Gy/1 fraction/day for 6 days; group 6 (n = 6), conventionally fractionated TAI of 1.7 Gy/1 fraction/day for 7 days. Mean epithelial length and diameter of seminiferous tubules of testicular tissues were determined after euthanasia.

RESULTS

Initially, a highly significant decrease in both the mean tubular diameter and epithelial height of the seminiferous tubules was demonstrated in all irradiated rats compared with the control group. No significant differences regarding both damage parameters were found between different hypofractionated radiation therapies. Both conventional radiation therapies reduced the epithelial height and mean diameter of the seminiferous tubules to a lesser extent when compared with 6 Gy/1 fraction/day hypofractionated therapy. It was further shown that parameter values were comparable between rats that received 3 Gy/day hypofractionated therapy and rats that received either of the two conventional therapies. Furthermore, although 4 Gy/day hypofractionation decreased tubular diameter and epithelial length to a greater degree compared with the conventional therapy of 1.7 Gy/1 fraction/day, no statistically significant difference was found when compared with conventional therapy of 2 Gy/1 fraction/day. Additionally, no statistically significant difference was demonstrated between the two types of conventional radiotherapy application.

CONCLUSION

The present study demonstrated that hypofractionated abdominal irradiation leads to more prominent tissue damage in the testes than conventional irradiation.

Measurement of mean cardiac dose for various breast irradiation techniques and corresponding risk of major cardiovascular event

After breast conserving surgery, early stage breast cancer patients are currently treated with a wide range of radiation techniques including whole breast irradiation (WBI), accelerated partial breast irradiation (APBI) using high-dose rate (HDR) brachytherapy, or 3D-conformal radiotherapy (3D-CRT). This study compares the mean heart’s doses for a left breast irradiated with different breast techniques. An anthropomorphic Rando phantom was modified with gelatin-based breast of different sizes and tumors located medially or laterally. The breasts were treated with WBI, 3D-CRT, or HDR APBI. The heart’s mean doses were measured with Gafchromic films and controlled with optically stimulated luminescent dosimeters. Following the model reported by Darby (1), major cardiac were estimated assuming a linear risk increase with the mean dose to the heart of 7.4% per gray. WBI lead to the highest mean heart dose (2.99 Gy) compared to 3D-CRT APBI (0.51 Gy), multicatheter (1.58 Gy), and balloon HDR (2.17 Gy) for a medially located tumor. This translated into long-term coronary event increases of 22, 3.8, 11.7, and 16% respectively. The sensitivity analysis showed that the tumor location had almost no effect on the mean heart dose for 3D-CRT APBI and a minimal impact for HDR APBI. In case of WBI large breast size and set-up errors lead to sharp increases of the mean heart dose. Its value reached 10.79 Gy for women with large breast and a set-up error of 1.5 cm. Such a high value could increase the risk of having long-term coronary events by 80%. Comparison among different irradiation techniques demonstrates that 3D-CRT APBI appears to be the safest one with less probability of having cardiovascular events in the future. A sensitivity analysis showed that WBI is the most challenging technique for patients with large breasts or when significant set-up errors are anticipated. In those cases, additional heart shielding techniques are required.

Sparing functional anatomical structures during intensity-modulated radiotherapy: an old problem, a new solution

ABSTRACT During intensity-modulated radiotherapy, an organ is usually assumed to be functionally homogeneous and, generally, its anatomical and spatial heterogeneity with respect to radiation response are not taken into consideration. However, advances in imaging and radiation techniques as well as an improved understanding of the radiobiological response of organs have raised the possibility of sparing the critical functional structures within various organs at risk during intensity-modulated radiotherapy. Here, we discuss these structures, which include the critical brain structure, or neural nuclei, and the nerve fiber tracts in the CNS, head and neck structures related to radiation-induced salivary and swallowing dysfunction, and functional structures in the heart and lung. We suggest that these structures can be used as potential surrogate organs at risk in order to minimize their radiation dose and/or irradiated volume without compromising the dose coverage of the target volume during radiation treatment.

Radiation-induced heart disease: an under-recognized entity?

OPINION STATEMENT

Radiation-induced heart disease (RIHD) represents a spectrum of cardiovascular disease in patients who have undergone mediastinal, thoracic, or breast radiotherapy (RT). RIHD may involve any cardiac structure and is a major cause of morbidity and mortality in cancer survivors. While large cohort studies have demonstrated that symptomatic RIHD is a common late finding in this population, the incidence of asymptomatic disease is likely to be even higher. Long-term follow-up with regular screening for RIHD plays an important role in the management of cancer survivors who have undergone RT. Aggressive modification of traditional cardiovascular risk factors such as hypertension, dyslipidemia, and cigarette smoking is essential in patients at risk for RIHD, as these have been shown to potentiate the risks of radiation. In patients with symptomatic RIHD, medical and/or percutaneous therapies are often preferable to surgical interventions in view of the increased surgical risk associated with radiation damage to surrounding tissues. Percutaneous revascularization should generally be favored over surgical revascularization. Transcatheter valve replacements have not been widely used in this population but may offer an alternative to high-risk surgical valve procedures. Pericardiectomy is usually associated with extremely poor short-term and long-term outcomes in patients with RIHD and should be avoided in most cases. Heart transplantation is also higher risk in patients with RIHD than in patients with other etiologies of heart failure, but may be considered in young patients without other comorbidities.

DEGRO practical guidelines: radiotherapy of breast cancer III--radiotherapy of the lymphatic pathways

AIM

The purpose of this work is to update the practical guidelines for adjuvant radiotherapy of the regional lymphatics of breast cancer published in 2008 by the breast cancer expert panel of the German Society of Radiation Oncology (DEGRO).

METHODS

A comprehensive survey of the literature concerning regional nodal irradiation (RNI) was performed using the following search terms: "breast cancer", "radiotherapy", "regional node irradiation". Recent randomized trials were analyzed for outcome as well as for differences in target definition. Field arrangements in the different studies were reproduced and superimposed on CT slices with individually contoured node areas. Moreover, data from recently published meta-analyses and guidelines of international breast cancer societies, yielding new aspects compared to 2008, provided the basis for defining recommendations according to the criteria of evidence-based medicine. In addition to the more general statements of the German interdisciplinary S3 guidelines updated in 2012, this paper addresses indications, targeting, and techniques of radiotherapy of the lymphatic pathways after surgery for breast cancer.

RESULTS

International guidelines reveal substantial differences regarding indications for RNI. Patients with 1-3 positive nodes seem to profit from RNI compared to whole breast (WBI) or chest wall irradiation alone, both with regard to locoregional control and disease-free survival. Irradiation of the regional lymphatics including axillary, supraclavicular, and internal mammary nodes provided a small but significant survival benefit in recent randomized trials and one meta-analysis. Lymph node irradiation yields comparable tumor control in comparison to axillary lymph node dissection (ALND), while reducing the rate of lymph edema. Data concerning the impact of 1-2 macroscopically affected sentinel node (SN) or microscopic metastases on prognosis are conflicting.

CONCLUSION

Recent data suggest that the current restrictive use of RNI should be scrutinized because the risk-benefit relationship appears to shift towards an improvement of outcome.