Residual Axillary Metastases in Node-Positive Breast Cancer Patients After Neoadjuvant Treatment: A Register-Based Study.

BACKGROUND: Lymph node (LN) metastasis after neoadjuvant chemotherapy (NACT) generally warrants axillary lymph node dissection, which opposes guidelines of upfront surgery in many cases. We investigated the risk of having additional metastases in the axilla when the LNs removed by targeted axillary dissection (TAD) harbored metastases after NACT. We aimed to identify subgroups suitable for de-escalated axillary treatment. METHODS: This register-based study used data from the Danish Breast Cancer Cooperative Group database. Data were analyzed with logistic regression models. The primary outcome was the metastatic burden in non-TAD LNs in patients with positive TAD LNs after NACT. RESULTS: Among 383 patients, < 66.6% positive TAD LNs (adjusted odds ratio [OR] 0.34, 95% confidence interval [CI] 0.17-0.62), only isolated tumor cells (ITCs) [OR 0.11, 95% CI < 0.01-0.82], and breast pathological complete response (pCR) [OR 0.07, 95% CI < 0.01-0.56] were associated with a low risk of having more than three positive non-TAD LNs. In 315 patients with fewer than three positive non-TAD LNs, the proportion of positive TAD LNs (OR 0.45, 95% CI 0.27-0.76 for 33.3-66.6% vs. > 66.6%), size of the TAD LN metastasis (OR 0.14, 95% CI 0.04-0.54 for ITC vs. macrometastasis), tumor size at diagnosis (OR 0.30, 95% CI 0.15-0.64 for 20-49 mm vs. ≥ 50 mm) and breast pCR (OR 0.38, 95% CI 0.15-0.96) were associated with residual LN metastases in the axilla. CONCLUSIONS: Breast pCR or ITC only in TAD LNs can, with reasonable certainty, preclude more than three positive non-TAD LNs. Additionally, patients with only ITCs in the TAD LN had a low risk of having any non-TAD LN metastases after NACT. De-escalated axillary treatment may be considered in both subgroups.

Comparison of outcomes between Hodgkin's lymphoma patients treated in and outside clinical trials: A study based on the EORTC-Dutch late effects cohort-linked data.

Studies have shown higher survival rates for patients with Hodgkin lymphoma (HL) treated within clinical trials compared to patients treated outside clinical trials. However, endpoints are often limited to overall survival (OS). In this retrospective cohort study, we investigated the effect of trial participation on OS, the incidence of relapse, second cancer, and cardiovascular disease (CVD). The study population consisted of patients with HL, aged between 14 and 51 years at diagnosis, who started their treatment between 1962 and 2002 at three Dutch cancer centres. Patients were either included in the EORTC Lymphoma Group trials (H1-H9) or treated according to standard guidelines at the time. After adjusting for differences in baseline characteristics, trial participation was associated with longer OS (median OS: 29.4 years [95%CI: 27.0-31.6] for treatment inside trials versus 27.4 years [95%CI: 26.0-28.5] for treatment outside trials, p = .046), a lower incidence of relapse (HR = 0.79, 95%CI: 0.63-0.98, p = .036) and a higher incidence of CVD (HR = 1.49, 95%CI: 1.23-1.79, p < .001). The trial effect for CVD was present only for patients treated before 1983. No evidence of differences in the incidence of second cancer was found. Consequently, essential results from clinical trials should be implemented into standard practice without undue delay.

Treating brain metastases in metastatic breast cancer: outcomes after stereotactic radiosurgery examined in a retrospective, single-center cohort analysis.

INTRODUCTION: We examined the role of receptor profiles and other prognostic factors in survival outcomes after stereotactic radiosurgery (SRS) for brain metastases in breast cancer patients, to help improve selection of candidates for SRS. MATERIAL AND METHODS: We included 149 consecutive patients who received SRS between 2012 and 2019 at the University Hospital of Copenhagen, Rigshospitalet, Denmark. Overall survival (OS) following SRS was determined through the Kaplan-Meier method, while CNS progression-free survival (CNS-PFS) was determined through competing risk analysis. Prognostic factors for both OS and CNS-PFS were evaluated through uni- and multivariate Cox regression and Fine-Gray models, respectively. The proportional hazards assumptions were tested through Schoenfeld residuals, and non-proportionality was accounted for by the inclusion of time-dependent variables. RESULTS: Median OS was 14.8 months for the entire cohort and was as follows for the four receptor profiles: 33.3 months for ER+/HER2+ (ER: estrogen receptor, HER2: human epidermal growth factor receptor 2), 11.0 months for ER+/HER2-, 17.7 months for ER-/HER2+, and 5.3 months for ER-/HER2-. In the multivariate model, the ER-/HER2- receptor profile (hazard ratio (HR): 2.00, 95% confidence interval (CI): 1.09-3.67) and the presence of extracranial visceral metastases (HR: 2.90, 95% CI: 1.53-5.50) were associated with worse OS. The ER+/HER2+ receptor profile (HR: 0.43, 95% CI: 0.19-0.96) and 5+ lines of treatment (HR: 0.40, 95% CI: 0.20-0.82) were both associated with improved OS. For CNS-PFS, 5+ lines of treatment (sub-distributional hazard ratio (SHR): 2.88, 95% CI: 1.06-7.81) was associated with worse CNS-PFS, while extracranial visceral metastases (SHR: 0.54, 95% CI: 0.30-0.97) was associated with reduced risk of CNS progression - which is primarily due to patients with extracranial metastases dying before developing new CNS progression. CONCLUSION: Extracranial visceral disease and the ER-/HER2- receptor profile were associated with poor survival outcomes following SRS.

Work and education interruption in long-term Hodgkin lymphoma survivors: an analysis among patients from nine EORTC-LYSA trials.

BACKGROUND: Disease-specific studies on the impact of Hodgkin lymphoma (HL) on education or work interruption and resumption are lacking. MATERIAL AND METHODS: In a cross-sectional study conducted among long-term HL survivors enrolled from 1964 to 2004 in nine randomised EORTC-LYSA trials, the interruption and resumption of education/work was investigated. Survivors alive 5-44 years after diagnosis who were studying or working at time of diagnosis were included (n = 1646). Patient and treatment characteristics were obtained from trial records. Education and work outcomes were collected using the Life Situation Questionnaire. Logistic regression was used to model education or work interruption; Cox regression was used to study resumption rates. RESULTS: Among survivors studying at time of diagnosis (n = 323), 52% (95% CI: 46-57%) interrupted their education; however, it was resumed within 24 months by 92% (95% CI: 87-96%). The probability of interruption decreased with time: the more recent the treatment era, the lower the risk (OR 0.70 per 10 years, 95% CI: 0.49-1.01). Treatment with radiotherapy (yes vs. no) was associated with a higher education resumption rate (HR 2.01, 95% CI 1.07-3.78) whereas age, sex, stage, radiotherapy field and chemotherapy were not.Among survivors working at time of diagnosis (n = 1323), 77% (95% CI: 75-79%) interrupted their work. However, it was resumed within 24 months by 86% (95% CI: 84%-88%). Women were more likely to interrupt their work as compared to men (OR 1.90, 95% CI: 1.44-2.51) and, when interrupted, less likely to resume work (HR 0.70, 95% CI: 0.61-0.80). Survivors with a higher educational level were less likely to interrupt their work (OR 0.68 for university vs. no high school, 95% CI: 0.46-1.03); and when interrupted, more likely to resume work (HR 1.50 for university vs. no high school, 95% CI: 1.21-1.86). Increasing age was also associated with lower resumption rates (HR 0.62 for age ≥50 vs. 18-29 years, 95% CI: 0.41-0.94). CONCLUSION: An interruption in education/work was common among long-term HL survivors. However, most of the survivors who interrupted their studies or work had resumed their activities within 24 months. In this study, no associations between survivors' characteristics and failure to resume education were observed. Female sex, age ≥50 years, and a lower level of education were found to be associated with not resuming work after treatment for HL.

Risk factors for cardiovascular disease in 5-year survivors of adolescent and young adult cancer: A Danish population-based cohort study.

BACKGROUND: An increased risk of metabolic syndrome has been reported for childhood cancer survivors and for adult survivors with certain cancer types. One previous study reported on the risk for diseases in the metabolic syndrome specifically among survivors of adolescent and young adult cancers. METHODS: The study comprised 11,822 five-year survivors of adolescent and young adult cancer (ages 15-39 years at diagnosis) who were diagnosed during the period from 1994 through 2009 in Denmark and a population-based comparison cohort of 76,024 individuals. The cohorts were linked to Danish nationwide registries for information on hospital contacts and purchase of prescription drugs related to metabolic syndrome, respectively. Standardized rate ratios (RRs) for hospital contacts (SHRRs) and prescriptions (SPRRs) with 95% CIs were calculated for diabetes, hyperlipidemia, and hypertension. RESULTS: Survivors had increased risks for hospital contacts and prescriptions for diabetes (SHRR, 1.21; 95% CI, 1.03-1.43; SPRR, 1.08; 95% CI, 0.96-1.23), hyperlipidemia (SHRR, 1.18; 95% CI, 1.00-1.40; SPRR, 1.16; 95% CI, 1.08-1.25), and hypertension (SHRR, 1.27; 95% CI, 1.15-1.41; SPRR, 1.25; 95% CI, 1.20-1.31). The highest risks for hospitalizations were among survivors of brain cancer (RR, 2.94 for diabetes) and Hodgkin lymphoma (RR, 2.40 for diabetes). Survivors of brain cancer and Hodgkin lymphoma were most likely to purchase prescription drugs for diseases in metabolic syndrome. CONCLUSIONS: Survivors of adolescent and young adult cancer are at increased risk of hospital contacts and purchase of prescription drugs for diseases in metabolic syndrome. Survivors at high risk should be followed closely to improve prevention, early detection, and management of these diseases to ultimately minimize the risk of cardiovascular diseases.

Biological optimization for mediastinal lymphoma radiotherapy - a preliminary study.

Purpose: In current radiotherapy (RT) planning and delivery, population-based dose-volume constraints are used to limit the risk of toxicity from incidental irradiation of organs at risks (OARs). However, weighing tradeoffs between target coverage and doses to OARs (or prioritizing different OARs) in a quantitative way for each patient is challenging. We introduce a novel RT planning approach for patients with mediastinal Hodgkin lymphoma (HL) that aims to maximize overall outcome for each patient by optimizing on tumor control and mortality from late effects simultaneously.Material and Methods: We retrospectively analyzed 34 HL patients treated with conformal RT (3DCRT). We used published data to model recurrence and radiation-induced mortality from coronary heart disease and secondary lung and breast cancers. Patient-specific doses to the heart, lung, breast, and target were incorporated in the models as well as age, sex, and cardiac risk factors (CRFs). A preliminary plan of candidate beams was created for each patient in a commercial treatment planning system. From these candidate beams, outcome-optimized (O-OPT) plans for each patient were created with an in-house optimization code that minimized the individual risk of recurrence and mortality from late effects. O-OPT plans were compared to VMAT plans and clinical 3DCRT plans.Results: O-OPT plans generally had the lowest risk, followed by the clinical 3DCRT plans, then the VMAT plans with the highest risk with median (maximum) total risk values of 4.9 (11.1), 5.1 (17.7), and 7.6 (20.3)%, respectively (no CRFs). Compared to clinical 3DCRT plans, O-OPT planning reduced the total risk by at least 1% for 9/34 cases assuming no CRFs and 11/34 cases assuming presence of CRFs.Conclusions: We developed an individualized, outcome-optimized planning technique for HL. Some of the resulting plans were substantially different from clinical plans. The results varied depending on how risk models were defined or prioritized.

Interobserver delineation uncertainty in involved-node radiation therapy (INRT) for early-stage Hodgkin lymphoma: on behalf of the Radiotherapy Committee of the EORTC lymphoma group.

BACKGROUND AND PURPOSE: In early-stage classical Hodgkin lymphoma (HL) the target volume nowadays consists of the volume of the originally involved nodes. Delineation of this volume on a post-chemotherapy CT-scan is challenging. We report on the interobserver variability in target volume definition and its impact on resulting treatment plans. MATERIALS AND METHODS: Two representative cases were selected (1: male, stage IB, localization: left axilla; 2: female, stage IIB, localizations: mediastinum and bilateral neck). Eight experienced observers individually defined the clinical target volume (CTV) using involved-node radiotherapy (INRT) as defined by the EORTC-GELA guidelines for the H10 trial. A consensus contour was generated and the standard deviation computed. We investigated the overlap between observer and consensus contour [Sørensen-Dice coefficient (DSC)] and the magnitude of gross deviations between the surfaces of the observer and consensus contour (Hausdorff distance). 3D-conformal (3D-CRT) and intensity-modulated radiotherapy (IMRT) plans were calculated for each contour in order to investigate the impact of interobserver variability on each treatment modality. Similar target coverage was enforced for all plans. RESULTS: The median CTV was 120 cm3 (IQR: 95-173 cm3) for Case 1, and 255 cm3 (IQR: 183-293 cm3) for Case 2. DSC values were generally high (>0.7), and Hausdorff distances were about 30 mm. The SDs between all observer contours, providing an estimate of the systematic error associated with delineation uncertainty, ranged from 1.9 to 3.8 mm (median: 3.2 mm). Variations in mean dose resulting from different observer contours were small and were not higher in IMRT plans than in 3D-CRT plans. CONCLUSIONS: We observed considerable differences in target volume delineation, but the systematic delineation uncertainty of around 3 mm is comparable to that reported in other tumour sites. This report is a first step towards calculating an evidence-based planning target volume margin for INRT in HL.

Optimizing the radiation therapy dose prescription for pediatric medulloblastoma: minimizing the life years lost attributable to failure to control the disease and late complication risk.

BACKGROUND: A mathematical framework is presented for simultaneously quantifying and evaluating the trade-off between tumor control and late complications for risk-based radiation therapy (RT) decision-support. To demonstrate this, we estimate life years lost (LYL) attributable to tumor recurrence, late cardiac toxicity and secondary cancers for standard-risk pediatric medulloblastoma (MB) patients and compare the effect of dose re-distribution on a common scale. METHODS: Total LYL were derived, based on the LYL attributable to radiation-induced late complications and the LYL from not controlling the primary disease. We compared the estimated LYL for three different treatments in 10 patients: 1) standard 3D conformal RT; 2) proton therapy; 3) risk-adaptive photon treatment lowering the dose to part of the craniospinal (CS) target volume situated close to critical risk organs. RESULTS: Late toxicity is important, with 0.75 LYL (95% CI 0.60-7.2 years) for standard uniform 24 Gy CS irradiation. However, recurrence risk dominates the total LYL with 14.2 years (95% CI 13.4-16.6 years). Compared to standard treatment, a risk-adapted strategy prescribing 12 Gy to the spinal volume encompassing the 1st-10th thoracic vertebrae (Th1-Th10), and 36 Gy to the remaining CS volume, estimated a LYL reduction of 0.90 years (95% CI -0.18-2.41 years). Proton therapy with 36 Gy to the whole CS volume was associated with significantly fewer LYL compared to the risk-adapted photon strategies, with a mean LYL difference of 0.50 years (95% CI 0.25-2.60 years). CONCLUSIONS: Optimization of RT prescription strategies considering both late complications and the risk of recurrence, an all-cause mortality dose painting approach, was demonstrated. The risk-adapted techniques compared favorably to the standard, and although in this context, the gain is small compared to estimated uncertainty, this study demonstrates a framework for all-cause mortality risk estimation, rather than evaluates direct clinical applicability of risk-adapted strategies.

Cardiovascular disease after cancer therapy.

Improvements in treatment and earlier diagnosis have both contributed to increased survival for many cancer patients. Unfortunately, many treatments carry a risk of late effects including cardiovascular diseases (CVDs), possibly leading to significant morbidity and mortality. In this paper we describe current knowledge of the cardiotoxicity arising from cancer treatments, outline gaps in knowledge, and indicate directions for future research and guideline development, as discussed during the 2014 Cancer Survivorship Summit organised by the European Organisation for Research and Treatment of Cancer (EORTC). Better knowledge is needed of the late effects of modern systemic treatments and of radiotherapy to critical structures of the heart, including the effect of both radiation dose and volume of the heart exposed. Research elucidating the extent to which treatments interact in causing CVD, and the mechanisms involved, as well as the extent to which treatments may increase CVD indirectly by increasing cardiovascular risk factors is also important. Systematic collection of data relating treatment details to late effects is needed, and great care is needed to obtain valid and generalisable results. Better knowledge of these cardiac effects will contribute to both primary and secondary prevention of late complications where exposure to cardiotoxic treatment is unavoidable. Also surrogate markers would help to identify patients at increased risk of cardiotoxicity. Evidence-based screening guidelines for CVD following cancer are also needed. Finally, risk prediction models should be developed to guide primary treatment choice and appropriate follow up after cancer treatment.

The effect on esophagus after different radiotherapy techniques for early stage Hodgkin's lymphoma.

INTRODUCTION: The cure rate of early stage Hodgkin's lymphoma (HL) is excellent; investigating the late effects of treatment is thus important. Esophageal toxicity is a known side effect in patients receiving radiotherapy (RT) to the mediastinum, although little is known of this in HL survivors. This study investigates the dose to the esophagus in the treatment of early stage HL using different RT techniques. Estimated risks of early esophagitis, esophageal stricture and cancer are compared between treatments. MATERIAL AND METHODS: We included 46 patients ≥ 15 years with supradiaphragmatic, clinical stage I-II HL, who received chemotherapy followed by involved node RT (INRT) to 30.6 Gy at our institution. INRT was planned with three-dimensional conformal RT (3DCRT). For each patient a volumetric modulated arc therapy (VMAT), proton therapy (PT) and mantle field (MF) treatment plan was simulated. Mean, maximum and minimum dose to the esophagus were extracted from the treatment plans. Risk estimates were based on dose-response models from clinical series with long-term follow-up. Statistical analyses were performed with repeated measures ANOVA using Bonferroni corrections. RESULTS: Mean dose to the esophagus was 16.4, 16.4, 14.7 and 34.2 Gy (p < 0.001) with 3DCRT, VMAT, PT and MF treatment, respectively. No differences were seen in the estimated risk of developing esophagitis, stricture or cancer with 3DCRT compared to VMAT (p = 1.000, p = 1.000, p = 0.356). PT performed significantly better with the lowest risk estimates on all parameters compared to the photon treatments, except compared to 3DCRT for stricture (p = 0.066). On all parameters the modern techniques were superior to MF treatment (p < 0.001). CONCLUSIONS: The estimated dose to the esophagus and the corresponding estimated risks of esophageal complications are decreased significantly with highly conformal RT compared to MF treatment. The number of patients presenting with late esophageal side effects will, thus, likely be minimal in the future.

Proton linear energy transfer and variable relative biological effectiveness for adolescent patients with Hodgkin lymphoma.

Objectives: Proton therapy has a theoretical dosimetric advantage due to the Bragg peak, but the linear energy transfer (LET), and therefore the relative biological effectiveness (RBE), increase at the end of range. For patients with Hodgkin lymphoma, the distal edge of beam is often located within or close to the heart, where elevated RBE would be of potential concern. The purpose of this study was to investigate the impact of RBE and the choice of beam arrangement for adolescent patients with mediastinal Hodgkin lymphoma. Methods: For three previously treated adolescent patients, proton plans with 1-3 fields were created to a prescribed dose of 19.8 Gy (RBE) in 11 fractions (Varian Eclipse v13.7), assuming an RBE of 1.1. Plans were recalculated using Monte-Carlo (Geant4 v10.3.3/Gate v8.1) to calculate dose-averaged LET. Variable RBE-weighted dose was calculated using the McNamara model, assuming an α/ß ratio of 2 Gy for organs-at-risk. Results: Although the LET decreased as the number of fields increased, the difference in RBE-weighted dose (Δdose) to organs-at-risk did not consistently decrease. Δdose values varied by patient and organ and were mostly of the order of 0-3 Gy (RBE), with a worst-case of 4.75 Gy (RBE) in near-maximum dose to the left atrium for one plan. Conclusions: RBE-weighted doses to organs-at-risk are sensitive to the choice of RBE model, which is of particular concern for the heart. Advances in knowledge: There is a need to remain cautious when evaluating proton plans for Hodgkin lymphoma, especially when near-maximum doses to organs-at-risk are considered.

Life years lost--comparing potentially fatal late complications after radiotherapy for pediatric medulloblastoma on a common scale.

BACKGROUND: The authors developed a framework for estimating and comparing the risks of various long-term complications on a common scale and applied it to 3 different techniques for craniospinal irradiation in patients with pediatric medulloblastoma. METHODS: Radiation dose-response parameters related to excess hazard ratios for secondary breast, lung, stomach, and thyroid cancer; heart failure, and myocardial infarction were derived from large published clinical series. Combined with age-specific and sex-specific hazards in the US general population, the dose-response analysis yielded excess hazards of complications for a cancer survivor as a function of attained age. After adjusting for competing risks of death, life years lost (LYL) were estimated based on excess hazard and prognosis of a complication for 3-dimensional conformal radiotherapy (3D CRT), volumetric modulated arc therapy (VMAT), and intensity-modulated proton therapy (IMPT). RESULTS: Lung cancer contributed most to the estimated LYL, followed by myocardial infarction, and stomach cancer. The estimates of breast or thyroid cancer incidence were higher than those for lung and stomach cancer incidence, but LYL were lower because of the relatively good prognosis. Estimated LYL ranged between 1.90 years for 3D CRT to 0.28 years for IMPT. In a paired comparison, IMPT was associated with significantly fewer LYL than both photon techniques. CONCLUSIONS: Estimating the risk of late complications is associated with considerable uncertainty, but including prognosis and attained age at an event to obtain the more informative LYL estimate added relatively little to this uncertainty.

An integrated approach to cardioprotection in lymphomas.

In potentially curable cancers, long-term survival depends not only on the successful treatment of the malignancy but also on the risks associated with treatment-related toxicity, especially cardiotoxicity. Malignant lymphomas affect patients at any age, with acute and late toxicity risks that could have a severe effect on morbidity, mortality, and quality of life. Although our understanding of chemotherapy-associated and radiotherapy-associated cardiovascular disease has advanced considerably, new drugs with potential cardiotoxicity have been introduced for the treatment of lymphomas. In this Review, we summarise the mechanisms of treatment-related cardiac injury, available clinical data, and protocols for optimising cardioprotection in lymphomas. We discuss ongoing research strategies to advance our knowledge of the molecular basis of drug-induced and radiation-induced toxicity. Additionally, we emphasise the potential for personalised follow-up and early detection, including the role of biomarkers and novel diagnostic tests, highlighting the role of the cardio-oncology team.

Employment situation among long-term Hodgkin lymphoma survivors in Europe: an analysis of patients from nine consecutive EORTC-LYSA trials.

PURPOSE: Little is known about the employment situation of long-term Hodgkin lymphoma (HL) survivors despite their young age at diagnosis and the favorable prognosis of the disease. In this cross-sectional study, we aim to describe the employment situation in a cohort of long-term HL survivors compared to the general population and investigate the associations with disease characteristics and treatment exposure. METHODS: HL survivors > 25 years (n = 1961) were matched 1:25 to controls (n = 49,025) from the European Union Labour Force Survey. Individual treatment information was obtained from trial records. Employment and socio-demographic characteristics were collected using the Life Situation Questionnaire. Logistic regression models were used to estimate associations between disease and treatment characteristics with employment status and work-related attitudes. RESULTS: At employment assessment, 69.7% of survivors (95% CI: 67.6-71.7%) were working; of these, 68.9% (95% CI: 66.3-71.3%) worked full-time, a figure comparable to that of controls (p value 0.17). The risk of not working was associated with increasing age at diagnosis, increasing age at survey, female sex, lower educational level, and relapse history. Of those who were at work during treatment, 16.8% (95% CI: 14.5-19.3%) stated their income had subsequently decreased, which was attributed to their HL by 65.4% (95% CI: 57.5-72.8). Among those not at work, 25.1% (95% CI: 20.7-29.8) survivors were disabled compared to only 14.5% (95% CI: 13.8-15.3%) of controls. CONCLUSIONS: In this cohort of HL survivors, employment status was comparable to that of the general population. However, increasing age at follow-up, female sex, lower educational level, and relapse history are risk factors for unemployment, a perceived decrease in income, and disability. IMPLICATIONS FOR CANCER SURVIVORS: To further improve follow-up care, special attention should be paid to these vulnerable subgroups.

Risk factors for radiation-induced hypothyroidism: a literature-based meta-analysis.

BACKGROUND: A systematic overview and meta-analysis of studies reporting data on hypothyroidism (HT) after radiation therapy was conducted to identify risk factors for development of HT. METHODS: Published studies were identified from the PubMed and Embase databases and by hand-searching published reviews. Studies allowing the extraction of odds ratios (OR) for HT in 1 or more of several candidate clinical risk groups were included. A meta-analysis of the OR for development of HT with or without each of the candidate risk factors was performed. Furthermore, studies allowing the extraction of radiation dose-response data were identified for a meta-analysis of the dose-response curve. RESULTS: Female gender (OR = 1.6; 95% confidence interval [CI], 1.3-1.9; P < .00001), surgery involving the thyroid gland (OR = 8.3; 95% CI, 5.7-12.0; P < .00001), or other neck surgery (OR = 1.7; 95% CI, 1.16-2.42; P = .006) were associated with a higher risk of HT. Caucasians were at higher risk of HT than African Americans (OR = 4.8; 95% CI, 2.8-8.5; P < .00001). The data showed association between lymphangiography and HT but with evidence of publication bias. There was a radiation dose-response relation with a 50% risk of HT at a dose of 45 Gy but with considerable variation in the dose response between studies. Chemotherapy and age were not associated with risk of HT in this analysis. CONCLUSIONS: Several clinical risk factors for HT were identified. The risk of HT increases with increasing radiation dose, but the specific radiation dose response varies between the studies. The most likely cause of this heterogeneity is differences in follow-up between studies.

Dose-response relationships for radiation-related heart disease: Impact of uncertainties in cardiac dose reconstruction.

BACKGROUND AND PURPOSE: Radiation-related heart disease (RRHD) can occur many decades after thoracic radiotherapy for Hodgkin lymphoma (HL) or childhood cancer (CC). To quantify the likely risk of RRHD for patients treated today, dose-response relationships derived from patients treated in previous decades are used. Publications presenting these dose-response relationships usually include estimates of uncertainties in the risks but ignore the effect of uncertainties in the reconstructed cardiac doses. MATERIALS/METHODS: We assessed the systematic and random uncertainties in the reconstructed doses for published dose-response relationships for RRHD risk in survivors of HL or CC. Using the same reconstruction methods as were used in the original publications, we reconstructed mean heart doses and, wherever possible, mean left-ventricular doses for an independent case-series of test patients. These patients had known, CT-based, cardiac doses which were compared with the reconstructed doses to estimate the magnitude of the uncertainties and their effect on the dose-response relationships. RESULTS: For all five reconstruction methods the relationship between reconstructed and CT-based doses was linear. For all but the simplest reconstruction method, the dose uncertainties were moderate, the effect of the systematic uncertainty on the dose-response relationships was less than 10%, and the effects of random uncertainty were small except at the highest doses. CONCLUSIONS: These results increase confidence in the published dose-response relationships for the risk of RRHD in HL and CC survivors. This may encourage doctors to use these dose-response relationships when estimating individualised risks for patients-an important aspect of personalising radiotherapy treatments today.