Optimized volumetric modulated arc therapy versus 3D-CRT for early stage mediastinal Hodgkin lymphoma without axillary involvement: a comparison of second cancers and heart disease risk

Consequences of ionizing radiation exposure to the cardiovascular system

Ionizing radiation is widely used in various industrial and medical applications, resulting in increased exposure for certain populations. Lessons from radiation accidents and occupational exposure have highlighted the cardiovascular and cerebrovascular risks associated with radiation exposure. In addition, radiation therapy for cancer has been linked to numerous cardiovascular complications, depending on the distribution of the dose by volume in the heart and other relevant target tissues in the circulatory system. The manifestation of symptoms is influenced by numerous factors, and distinct cardiac complications have previously been observed in different groups of patients with cancer undergoing radiation therapy. However, in contemporary radiation therapy, advances in treatment planning with conformal radiation delivery have markedly reduced the mean heart dose and volume of exposure, and these variables are therefore no longer sole surrogates for predicting the risk of specific types of heart disease. Nevertheless, certain cardiac substructures remain vulnerable to radiation exposure, necessitating close monitoring. In this Review, we provide a comprehensive overview of the consequences of radiation exposure on the cardiovascular system, drawing insights from various cohorts exposed to uniform, whole-body radiation or to partial-body irradiation, and identify potential risk modifiers in the development of radiation-associated cardiovascular disease.

Is oligometastatic disease an applicable and useful concept in haematologic malignancies? A narrative review of radiation therapy standards, modern techniques, and innovations

PURPOSE

Haematologic malignancies are particular in that they can generally be cured, even when distant metastases are present at diagnosis, unlike solid malignancies. Systemic treatments, including chemotherapy, targeted therapies, and immunotherapy, are the standard of care with excellent results. The considerable progress made in the management of these diseases in the last 20years has redefined the role of radiation therapy as minor in many clinical situations. We propose a literature review of data, showing that radiation therapy still has a role in curative, salvage, and palliative therapy situations.

MATERIAL AND METHODS

A document and literature search was carried out in the following databases: Medline and ClinicalTrial.gov, for the terms "radiotherapy", "haematologic malignancies", "Hodgkin lymphoma", "non-Hodgkin lymphoma", "CAR T cells", "multiple myeloma", "solitary plasmocytoma", "intensity-modulated radiotherapy", "extracranial stereotactic body radiation therapy" and "proton therapy references".

RESULTS

Haemopathological malignancies include a wide range of diseases and radiation therapy indications have been assessed over the past 20years. Currently, radiation therapy is indicated for localized disease (solitary plasmocytoma), as an adjuvant (Hodgkin lymphoma), in palliative settings, or after systemic treatment in relapsed patients (chimeric antigen receptor [CAR] T-cells) with a low recurrence burden, which can therefore be considered "oligorecurrence". Radiation therapy, through total body irradiation, has important indications, thanks to its immunomodulatory and/or myeloablative effects. Moreover, recent technological developments have made possible significant improvement in safety, contributing to radiation therapy being positioned in the treatment strategy of several indications.

CONCLUSIONS

Given the effectiveness of systemic treatments in hematologic malignancies, the oligometastasis stage is of little importance. A curative intent after local radiation therapy, even advanced stage, is possible, both with residual disease for advanced Hodgkin lymphoma, aggressive non-Hodgkin lymphoma, or solitary plasmocytoma, and even without evidence of disease after chemotherapy for Hodgkin or non-Hodgkin lymphoma. The role of new treatments, such as CAR T cells, allows us to consider radiation therapy after systemic treatment of relapsed diseases with low volume recurrence, which can be considered oligorecurrence.

A Beam Angle Selection Method to Improve Plan Robustness Against Position Error in Intensity-Modulated Radiotherapy for Left-Sided Breast Cancer

PURPOSE

We report a dosimetric study in whole breast irradiation (WBI) of plan robustness evaluation against position error with two radiation techniques: tangential intensity-modulated radiotherapy (T-IMRT) and multi-angle IMRT (M-IMRT).

METHODS

Ten left-sided patients underwent WBI were selected. The dosimetric characteristics, biological evaluation and plan robustness were evaluated. The plan robustness quantification was performed by calculating the dose differences (Δ) of the original plan and perturbed plans, which were recalculated by introducing a 3-, 5-, and 10-mm shift in 18 directions.

RESULTS

M-IMRT showed better sparing of high-dose volume of organs at risk (OARs), but performed a larger low-dose irradiation volume of normal tissue. The greater shift worsened plan robustness. For a 10-mm perturbation, greater dose differences were observed in T-IMRT plans in nearly all directions, with higher ΔD98%, ΔD95%, and ΔDmean of CTV Boost and CTV. A 10-mm shift in inferior (I) direction induced CTV Boost in T-IMRT plans a 1.1 (ΔD98%), 1.1 (ΔD95%), and 1.7 (ΔDmean) times dose differences greater than dose differences in M-IMRT plans. For CTV Boost, shifts in the right (R) and I directions generated greater dose differences in T-IMRT plans, while shifts in left (L) and superior (S) directions generated larger dose differences in M-IMRT plans. For CTV, T-IMRT plans showed higher sensitivity to a shift in the R direction. M-IMRT plans showed higher sensitivity to shifts in L, S, and I directions. For OARs, negligible dose differences were found in V20 of the lungs and heart. Greater ΔDmax of the left anterior descending artery (LAD) was seen in M-IMRT plans.

CONCLUSION

We proposed a plan robustness evaluation method to determine the beam angle against position uncertainty accompanied by optimal dose distribution and OAR sparing.

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.

Proton Therapy in Supradiaphragmatic Lymphoma: Predicting Treatment-Related Mortality to Help Optimize Patient Selection

PURPOSE

In some patients with Hodgkin lymphoma (HL), proton beam therapy (PBT) may reduce the risk of radiation-related cardiovascular disease (CVD) and second cancers (SC) compared with photon radiation therapy (RT). Our aim was to identify patients who benefit the most from PBT in terms of predicted 30-year absolute mortality risks (AMR30) from CVD and SC, taking into account individual background, chemotherapy, radiation, and smoking-related risks.

METHODS AND MATERIALS

Eighty patients with supradiaphragmatic HL treated with PBT between 2015 and 2019 were replanned using optimal photon RT. To identify patients predicted to derive the greatest benefit from PBT compared with photon RT, doses and AMR30 from CVD and SC of the lung, breast, and esophagus were compared for all patients and across patient subgroups.

RESULTS

For patients with mediastinal disease below the origin of the left main coronary artery (n = 66; 82%), PBT reduced the mean dose to the heart, left ventricle, and heart valves by 1.0, 2.7, and 3.6 Gy, respectively. Based on U.S. mortality rates, PBT reduced CVD AMR30 by 0.2%, from 5.9% to 5.7%. The benefit was larger if the mediastinal disease overlapped longitudinally with the heart by ≥40% (n = 23; 29%). PBT reduced the mean dose to the heart, left ventricle, and heart valves by 3.2, 5.6, and 5.1 Gy, respectively, and reduced CVD AMR30 by 0.8%, from 7.0% to 6.2%. For patients with axillary disease (n = 25; 31%), PBT reduced the mean lung dose by 2.8 Gy and lung cancer AMR30 by 0.6%, from 2.7% to 2.1%. Breast and esophageal doses were also lower with PBT, but the effects on AMR30 were negligible. The effect of smoking on CVD and lung cancer AMR30 was much larger than radiation and chemotherapy and the differences between radiation modalities.

CONCLUSIONS

The predicted benefit of PBT is not universal and limited to certain categories of patients with lymphoma and lower mediastinal or axillary disease. Smoking cessation should be strongly encouraged in smokers who require thoracic RT.

Second Cancers in Classical Hodgkin Lymphoma and Diffuse Large B-Cell Lymphoma: A Systematic Review by the Fondazione Italiana Linfomi

BACKGROUND

The increase of lymphoma patient survival led to a modification of the incidence of long-term sequelae, including second malignancies (SM). Several groups have dealt with the incidence of SM, according to the primary treatment; however, a standardized approach for the early detection and screening of SM in the population of lymphoma survivors should be implemented.

METHODS

A systematic review was conducted by Fondazione Italiana Linfomi (FIL), in order to define the incidence of SM, the impact of modern radiotherapy on SM risk, and the usefulness of tailored follow-up and screening strategies for early diagnosis of SM. Classical Hodgkin lymphoma (cHL) and diffuse large B-cell lymphoma (DLBCL) survivors were investigated. The MEDLINE, Embase, and Cochrane Library databases were checked for relevant reports published up to January 2020. The selection process was reported according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.

RESULTS

A total of 27 full-text manuscripts resulted as eligible for the analysis. The incidence of SM in cHL patients treated with ABVD was higher compared to the general population and was even higher in patients treated with intensified regimens. The risk increased over time, as well as after 10-15 years from therapy, and was augmented by radiotherapy exposure. In DLBCL, more intensive regimens (i.e., R-CHOEP or R-MegaCHOEP) vs. R-CHOP were associated with a higher SM incidence. Salvage chemotherapy and autologous stem cell transplants increased the risk of SM in both cHL and DLBCL cohorts. A lower incidence of SM, particularly of breast cancer (BC), was shown in cohorts of cHL survivors treated with reduced radiation volumes and doses (involved fields vs. extended fields), but robust trials are still lacking. Considering the advantage of a structured screening for early detection of SM, all the included studies regarded cHL survivors and screening strategy for early BC detection. Moreover, the authors discuss additional papers, to guide the early diagnosis of lung, colorectal, skin, and thyroid cancer in patients at risk due to family history, drug or RT exposure, or unhealthy lifestyles. These screening strategies all passed through patient awareness.

CONCLUSION

A modern approach to chemotherapy and radiotherapy led to a lower risk of SM, which should be confirmed over time. Early detection of secondary cancers could be achieved through a tailored screening program, according to the individual risk profile.

Radiotherapy of lymphomas

Radiotherapy for Hodgkin lymphomas has evolved a lot over time, but still plays an important role, almost always in addition to chemotherapy, for the management of the early stages. The major objective is to preserve the quality of life of patients who will be cured from this disease in the vast majority of cases. Also, the personalization of the indications for the purpose of de-escalating toxicity is very refined and is essentially based on the pre- and pertherapeutic assessment by FDG-PET. The indications for radiotherapy are more limited for non-Hodgkin lymphomas, but the same principles are found, regardless of the histological type. We present the update of the recommendations of the French society of oncological radiotherapy for radiotherapy of lymphomas, which remains a very evolving field in terms of therapeutic strategy and evaluation.

Impact of Radiation Therapy After High Dose Chemotherapy and Autologous Hematopoietic Stem Cell Transplantation in Patients With Relapsed/Refractory Lymphomas: A Single Center Experience

INTRODUCTION

After high dose chemotherapy (HDC) and autologous stem cell transplantation (auto-SCT), in patients with relapsed/refractory diffuse large B cell lymphoma (DLBCL) and Hodgkin lymphoma (HL), involved field radiation therapy (RT) for consolidation and residual/progressive disease (PD) eradication is a common practice.

MATERIALS AND METHODS

Retrospective single-institution cohort analysis to evaluate the impact of early RT after HDC auto-SCT.

RESULTS

Between 1996 and October 2019, 153 patients (43 DLBCL, 110 HL) underwent RT after HDC auto-SCT. Males 95 (62%), females 58 (38%), median age 24 years. Indications for RT was consolidation 65%: residual disease eradication 16%: and PD eradication 19%. For DLBCL, the median overall survival (OS) for the above indications was not reached (NR):NR:2 months and the KM 5-year OS was 72.6%:64.3%:12.5% respectively (P ≤ .000). Pair-wise analysis showed that consolidation versus residual disease eradication had no difference (P = .88) but both were superior to PD disease eradication (P ≤ 000 and P = .005 respectively). For HL, indication for RT was, 54%:23%:24% respectively. The median OS was NR:NR:28.8 months and KM 5-year OS was 82.3%:78%:30% respectively (P ≤ .000). Pair-wise analysis showed that consolidation versus residual disease eradication had no difference (P = .98) but both were superior to the PD eradication group (P ≤ 000). RT was well tolerated with no significant long-term toxicity.

CONCLUSION

Post HDC auto-SCT RT was well tolerated. DLBCL and HL patients with residual disease treated with the RT had similar long-term survival as those who received RT for consolidation. RT failed to improve the poor survival in patients with post-HDC auto-SCT PD.

A Systematic Review on Intensity Modulated Radiation Therapy for Mediastinal Hodgkin's Lymphoma

BACKGROUND

Secondary malignant neoplasms (SMNs) and cardiovascular diseases induced by chemotherapy and radiotherapy represent the main cause of excess mortality for early-stage Hodgkin lymphoma patients, especially when the mediastinum is involved. Conformal radiotherapy techniques such as Intensity-Modulated Radiation Therapy (IMRT) could allow a reduction of the dose to the organs-at-risk (OARs) and therefore limit long-term toxicity.

METHODS

We performed a systematic review of the current literature regarding comparisons between IMRT and conventional photon beam radiotherapy, or between different IMRT techniques, for the treatment of mediastinal lymphoma.

RESULTS AND CONCLUSIONS

IMRT allows a substantial reduction of the volumes of OARs exposed to high doses, reducing the risk of long-term toxicity. This benefit is conterbalanced by the increase of volumes receiving low doses, that could potentially increase the risk of SMNs. Treatment planning should be personalized on patient and disease characteristics. Dedicated techniques such as "butterfly" VMAT often provide the best trade-off.

Advanced Radiotherapy Techniques for Mediastinal Lymphomas: Results from an Italian Survey

Background: Multiple methods have been implemented to limit the impact of radiotherapy on patients affected by mediastinal lymphoma, including breathing control techniques, image-guided radiotherapy (IGRT) and intensity-modulated radiotherapy (IMRT), although the actual diffusion of such techniques is unclear. No surveys have been published to date evaluating the techniques adopted at different centers. Methods: A survey with a dedicated questionnaire was submitted to 195 Italian radiotherapy centers, assessing items regarding the characteristics of the center and clinical practice in the treatment of mediastinal lymphomas. Results: A total of 43 centers (22%) responded, the majority of which were university hospitals (37.2%) or cancer care centers (27.9%). In 95.4% of the centers, IMRT was used in the clinical practice, and the most frequently employed techniques were VMAT (48.8% of centers) and non-rotational IMRT (31.7%). Comparison of multiple plans was performed by 66.7% of the responding centers. Dose constraints for organs at risk were consistently prescribed. IGRT techniques were adopted by 93% of the centers, while breathing control or gating techniques were routinely used by only 25.6% of the centers. A necessity to standardize OAR constraints and define guidelines was perceived by almost all participants. Conclusions: Modern radiotherapy techniques are widely used in the Italian centers, although with heterogeneous characteristics.

Development and Implementation of Proton Therapy for Hodgkin Lymphoma: Challenges and Perspectives

Simple Summary

Hodgkin lymphoma (HL) is a highly curable disease; proton therapy for mediastinal HL irradiation might theoretically reduce late toxicities compared with classical radiotherapy techniques. However, optimal patient selection for this technique is subject to debate. While implementation at a larger scale of proton therapy for HL may face organizational, political, and societal challenges, new highly effective systematic drugs are being widely evaluated for this disease.

Abstract

Consolidative radiation therapy for early-stage Hodgkin lymphoma (HL) improves progression-free survival. Unfortunately, first-generation techniques, relying on large irradiation fields, were associated with an increased risk of secondary cancers, and of cardiac and lung toxicity. Fortunately, the use of smaller target volumes combined with technological advances in treatment techniques currently allows efficient organs-at-risk sparing without altering tumoral control. Recently, proton therapy has been evaluated for mediastinal HL treatment due to its potential to significantly reduce the dose to organs-at-risk, such as cardiac substructures. This is expected to limit late radiation-induced toxicity and possibly, second-neoplasm risk, compared with last-generation intensity-modulated radiation therapy. However, the democratization of this new technique faces multiple issues. Determination of which patient may benefit the most from proton therapy is subject to intense debate. The development of new effective systemic chemotherapy and organizational, societal, and political considerations might represent impediments to the larger-scale implementation of HL proton therapy. Based on the current literature, this critical review aims to discuss current challenges and controversies that may impede the larger-scale implementation of mediastinal HL proton therapy.

Current Situation of Proton Therapy for Hodgkin Lymphoma: From Expectations to Evidence

Consolidative radiation therapy (RT) is of prime importance for early-stage Hodgkin lymphoma (HL) management since it significantly increases progression-free survival (PFS). Nevertheless, first-generation techniques, relying on large irradiation fields, delivered significant radiation doses to critical organs-at-risk (OARs, such as the heart, to the lung or the breasts) when treating mediastinal HL; consequently, secondary cancers, and cardiac and lung toxicity were substantially increased. Fortunately, HL RT has drastically evolved and, nowadays, state-of-the-art RT techniques efficiently spare critical organs-at-risks without altering local control or overall survival. Recently, proton therapy has been evaluated for mediastinal HL treatment, due to its possibility to significantly reduce integral dose to OARs, which is expected to limit second neoplasm risk and reduce late toxicity. Nevertheless, clinical experience for this recent technique is still limited worldwide. Based on current literature, this critical review aims to examine the current practice of proton therapy for mediastinal HL irradiation.

The impact of modern radiotherapy on radiation-induced late sequelae: Focus on early-stage mediastinal classical Hodgkin Lymphoma. A critical review by the Young Group of the Italian Association of Radiotherapy and Clinical Oncology (AIRO)

INTRODUCTION

The historically feared radiation-induced secondary cancers and cardiac toxicities observed among mediastinal classical Hodgkin Lymphoma (cHL) patients may still negatively burden the benefit of radiotherapy among long-term survivors. Modern radiotherapy (RT) delivery techniques, including intensity-modulated RT (IMRT) and deep inspiration breath-hold (DIBH) solutions, are drastically changing this scenario. Results of a literature overview are reported and discussed in this paper.

MATERIALS AND METHODS

Key references were derived from a PubMed query. Hand searching and clinicaltrials.gov were also used.

RESULTS

This paper contains a narrative report and a critical discussion of organs-at-risk dose-volume metrics linked with radiation-induced toxicities in cHL patients.

CONCLUSIONS

The scenario of early-stage cHL presents long-life expectancies, thus the goal of treatment should aim at maintaining high cure rates and limiting the onset of late complications. Further evaluations of dosimetric measures and clinical outcomes are warranted to identify patients at higher risk to target treatment tailoring.

On the Importance of Individualized, Non-Coplanar Beam Configurations in Mediastinal Lymphoma Radiotherapy, Optimized With Automated Planning

Background and Purpose

Literature is non-conclusive regarding selection of beam configurations in radiotherapy for mediastinal lymphoma (ML) radiotherapy, and published studies are based on manual planning with its inherent limitations. In this study, coplanar and non-coplanar beam configurations were systematically compared, using a large number of automatically generated plans.

Material and Methods

An autoplanning workflow, including beam configuration optimization, was configured for young female ML patients. For each of 25 patients, 24 plans with different beam configurations were generated with autoplanning: 11 coplanar CP_x plans and 11 non-coplanar NCP_x plans with x = 5 to 15 IMRT beams with computer-optimized, patient-specific configurations, and the coplanar VMAT and non-coplanar Butterfly VMAT (B-VMAT) beam angle class solutions (600 plans in total).

Results

Autoplans compared favorably with manually generated, clinically delivered plans, ensuring that beam configuration comparisons were performed with high quality plans. There was no beam configuration approach that was best for all patients and all plan parameters. Overall there was a clear tendency towards higher plan quality with non-coplanar configurations (NCP_x≥12 and B-VMAT). NCP_x≥12 produced highly conformal plans with on average reduced high doses in lungs and patient and also a reduced heart Dmean, while B-VMAT resulted in reduced low-dose spread in lungs and left breast.

Conclusions

Non-coplanar beam configurations were favorable for young female mediastinal lymphoma patients, with patient-specific and plan-parameter-dependent dosimetric advantages of NCP_x≥12 and B-VMAT. Individualization of beam configuration approach, considering also the faster delivery of B-VMAT vs. NCP_x≥12, can importantly improve the treatments.

Primary Mediastinal B Cell Lymphoma in the Positron-Emission Tomography Era Executive Summary of the American Radium Society Appropriate Use Criteria

PURPOSE

Primary mediastinal B cell lymphoma (PMBCL) is a highly curable subtype of non-Hodgkin lymphoma that is diagnosed predominantly in adolescents and young adults. Consequently, long-term treatment-related morbidity is critical to consider when devising treatment strategies that include different chemoimmunotherapy strategies with or without radiation therapy. Furthermore, adaptive approaches using the end-of-chemotherapy (EOC) positron emission tomography (PET)/computed tomography (CT) scanning may help to determine which patients may benefit from additional therapies. We aimed to develop evidence-based guidelines for treating these patients.

METHODS AND MATERIALS

We conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline using the PubMed database. The ARS expert committee, composed of radiation oncologists, hematologists, and pediatric oncologists, developed consensus guidelines using the modified Delphi framework.

RESULTS

Nine studies met the full criteria for inclusion based on reporting outcomes on patients with primary mediastinal B cell lymphoma with EOC PET/CT response scored with the 5-point Deauville scale. These studies formed the evidence for these guidelines in managing patients with PMBCL according to the EOC PET response, including after a 5-point Deauville scale of 1 to 3, 4, or 5, and for patients with relapsed and refractory disease. The expert group also developed guidance on radiation simulation, treatment planning, and plan evaluation based on expert opinion.

CONCLUSIONS

Various treatment approaches exist in the management of PMBCL, including different chemoimmunotherapy regimens, the use of consolidative radiation therapy, and adaptive approaches based on EOC PET/CT response. These guidelines can be used by practitioners to provide appropriate treatment according to different disease scenarios.

Favorable Outcome After Adjuvant Involved-Field Radiotherapy After Autologous Hematopoietic Stem-Cell Transplantation in Patients With High-Risk Relapsed/Refractory Lymphoma: A Single-Center Experience

BACKGROUND

Patients with refractory or relapsed lymphoma diagnosed with bulky disease at relapse or with residual disease after salvage treatment are considered to have a dismal outcome, even after autologous hematopoietic stem-cell transplantation, as a result of disease recurrence. To minimize the risk of relapse after receipt of a transplant, involved-field radiotherapy (IFRT) to sites of either bulky or localized residual disease has been utilized; however, the ideal timing for irradiation remains controversial. The aim of this study was to assess the safety and efficacy of IFRT in the early period after transplantation.

PATIENTS AND METHODS

We retrospectively evaluated the outcome of 24 autografted patients with relapsed/refractory lymphoma who presented with bulky disease at relapse or who had a persistent localized residual mass after salvage treatment and consolidated with IFRT within 4 months after autografting.

RESULTS

No significant toxicity was noticed during the early postradiotherapy period, while graft function was not impaired. After a median follow-up of 3 years for survivors, 21 patients were alive, 19 of whom were event free, while 2 patients died of disease recurrence and 1 died of treatment-related myelodysplastic syndrome. The 3-year overall, lymphoma relapse-free, and event-free survival rates were 86%, 86%, and 82%, respectively.

CONCLUSION

Taking into consideration the poor-risk features of the study cohort, IFRT provided early after autologous hematopoietic stem-cell transplantation showed a safe and well-tolerated toxicity profile and demonstrated long-term effective tumor control, as reflected in the promising survival rates.

Hodgkin lymphoma

Hodgkin lymphoma (HL) is a B cell lymphoma characterized by few malignant cells and numerous immune effector cells in the tumour microenvironment. The incidence of HL is highest in adolescents and young adults, although HL can affect elderly individuals. Diagnosis is based on histological and immunohistochemical analyses of tissue from a lymph node biopsy; the tissue morphology and antigen expression profile enable classification into one of the four types of classic HL (nodular sclerosis, mixed cellularity, lymphocyte-depleted or lymphocyte-rich HL), which account for the majority of cases, or nodular lymphocyte-predominant HL. Although uncommon, HL remains a crucial test case for progress in cancer treatment. HL was among the first systemic neoplasms shown to be curable with radiation therapy and multiagent chemotherapy. The goal of multimodality therapy is to minimize lifelong residual treatment-associated toxicity while maintaining high levels of effectiveness. Recurrent or refractory disease can be effectively treated or cured with high-dose chemotherapy followed by autologous haematopoietic stem cell transplantation, and prospective trials have demonstrated the potency of immunotherapeutic approaches with antibody-drug conjugates and immune checkpoint inhibitors. This Primer explores the wealth of information that has been assembled to understand HL; these updated observations verify that HL investigation and treatment remain at the leading edge of oncological research.

Adoption of Expansion Margins to Reduce the Dose Received by the Coronary Arteries and the Risk of Cardiovascular Events in Lymphoma Patients

PURPOSE

Mediastinal radiation therapy (RT) in patients with lymphoma implies involuntary coronary artery (CA) exposure, resulting in an increased risk of coronary artery disease (CAD). Accurate delineation of CAs may spare them from higher RT doses. However, heart motion affects the estimation of the dose received by CAs. An expansion margin (planning organ at risk volume [PRV]), encompassing the nearby area where CAs displace, may compensate for these uncertainties, reducing CA dose and CAD risk. Our study aimed to evaluate if a planning process optimized on CA-specific PRVs, rather than just on CAs, could provide any dosimetric or clinical benefit.

METHODS AND MATERIALS

Forty patients receiving RT for mediastinal lymphomas were included. We contoured left main trunk, left anterior descending, left circumflex, and right coronary arteries. An isotropic PRV was then applied to all CAs, in accordance with literature data. A comparison was then performed by optimizing treatment plans either on CAs or on PRVs, to detect any difference in CA sparing in terms of maximum (D_max), median (D_med), and mean (D_mean) dose. We then investigated, through risk modeling, if any dosimetric benefit obtained with the PRV-related optimization process could translate to a lower risk of ischemic complications.

RESULTS

Plan optimization on PRVs demonstrated a significant dose reduction (range, 7%-9%) in D_max, D_med, and D_mean for the whole coronary tree, and even higher dose reductions when vessels were located 5- to 20-mm from PTV (range, 13%-15%), especially for left main trunk and left circumflex (range, 16%-21%). This translated to a mean risk reduction of developing CAD of 12% (P < .01), which increased to 17% when CAs were located 5- to 20-mm from PTV.

CONCLUSIONS

Integration of CA-related PRVs in the optimization process reduces the dose received by CAs and translates to a meaningful prevention of CAD risk in patients with lymphoma treated with mediastinal RT.

Fondazione Italiana Linfomi (FIL) expert consensus on the use of intensity-modulated and image-guided radiotherapy for Hodgkin's lymphoma involving the mediastinum

Aim

Advances in therapy have resulted in improved cure rates and an increasing number of long-term Hodgkin's lymphoma (HL) survivors. However, radiotherapy (RT)-related late effects are still a significant issue, particularly for younger patients with mediastinal disease (secondary cancers, heart diseases). In many Centers, technological evolution has substantially changed RT planning and delivery. This consensus document aims to analyze the current knowledge of Intensity-Modulated Radiation Therapy (IMRT) and Image-Guided Radiation Therapy (IGRT) for mediastinal HL and formulate practical recommendations based on scientific evidence and expert opinions.

Methods

A dedicated working group was set up within the Fondazione Italiana Linfomi (FIL) Radiotherapy Committee in May 2018. After a first meeting, the group adopted a dedicated platform to share retrieved articles and other material. Two group coordinators redacted a first document draft, that was further discussed and finalized in two subsequent meetings. Topics of interest were: 1) Published data comparing 3D-conformal radiotherapy (3D-CRT) and IMRT 2) dose objectives for the organs at risk 3) IGRT protocols and motion management.

Results

Data review showed that IMRT might allow for an essential reduction in the high-dose regions for all different thoracic OAR. As very few studies included specific dose constraints for lungs and breasts, the low-dose component for these OAR resulted slightly higher with IMRT vs. 3D-CRT, depending on the technique used. We propose a set of dose objectives for the heart, breasts, lungs, and thyroid. The use of IGRT is advised for margin reduction without specific indications, such as the use of breath-holding techniques. An individual approach, including comparative planning and considering different risk factors for late morbidity, is recommended for each patient.

Conclusions

As HL therapy continues to evolve, with an emphasis on treatment reduction, radiation oncologists should use at best all the available tools to minimize the dose to organs at risk and optimize treatment plans. This document provides indications on the use of IMRT/IGRT based on expert consensus, providing a basis for clinical implementation and future development.

A case report evaluating combined effect of intensity-modulated radiotherapy and deep inspiratory breath-hold for mediastinal lymphoma: A dosimetric analysis

Excellent survival has been reported after combined modality treatment in bulky mediastinal Hodgkin's lymphoma. Late effects such as cardiac morbidity and secondary cancers have been reported after radiotherapy (RT), especially in young adults. Advanced RT techniques such as deep inspiratory breath-hold (DIBH), intensity-modulated RT (IMRT), and volumetric arc therapy have been used recently to reduce these late effects with encouraging results. We hereby present a case report evaluating combined effect of DIBH and IMRT in a young adult with mediastinal lymphoma.

Hybrid planning techniques for hypofractionated whole-breast irradiation using flattening filter-free beams

OBJECTIVE

The aim of this study was to assess the feasibility of flattening filter-free (FFF) photon beams in hybrid intensity-modulated radiation therapy (H-IMRT) and hybrid volumetric modulated arc therapy (H-VMAT) for left-sided whole-breast radiation therapy with a boost volume (RT) using a hypofractionated dose regimen.

PATIENTS AND METHODS

RT plans of 25 patients with left-sided early-stage breast cancer were created with H‑IMRT and H‑VMAT techniques under breath-hold conditions using 6‑MV FFF beams. In hybrid techniques, three-dimensional conformal radiotherapy (3DCRT) plans were kept as base-dose plans for the VMAT and IMRT plans. In addition, H‑IMRT in step-and-shoot mode was also calculated to assess its achievability with FFF beams.

RESULTS

All hybrid plans achieved the expected target coverage. H‑VMAT showed better coverage and homogeneity index results for the boost target (p < 0.002), while H‑IMRT presented better results for the whole-breast target (p < 0.001). Mean doses to normal tissues were comparable between both plans, while H‑IMRT reduced the low-dose levels to heart and ipsilateral lung (p < 0.05). H‑VMAT revealed significantly better results with regard to monitor units (MU) and treatment time (p < 0.001).

CONCLUSION

The 6‑MV FFF beam technique is feasible for large-field 3DCRT-based hybrid planning in whole-breast and boost planning target volume irradiation. For breath-hold patients, the H‑VMAT plan is superior to H‑IMRT for hypofractionated dose regimens, with reduced MU and treatment delivery time.

Proton Therapy For Lymphomas: Current State Of The Art

The combination of brief chemo-radiotherapy provides high cure rates and represents the first line of treatment for many lymphoma patients. As a result, a high proportion of long-term survivors may experience treatment-related toxic events many years later. Excess and unintended radiation dose to organs at risk (particularly heart, lungs and breasts) may translate in an increased risk of cardiovascular events and second cancers after a few decades. Minimizing dose to organs at risk is thus pivotal to restrain the risk of long-term complications. Proton therapy, with its peculiar physic properties, may help to better spare organs at risk and consequently to reduce toxicities especially in patients receiving mediastinal radiotherapy. Herein, we review the physical basis of proton therapy and the rationale for its implementation in lymphoma patients, with a detailed description of the clinical data. We also discuss the potential disadvantages and uncertainties of protons that may limit their application and critically review the dosimetric studies comparing the risk of late complications between proton and photon radiotherapy.

Advantage of proton-radiotherapy for pediatric patients and adolescents with Hodgkin's disease

Abstract

Radiotherapy is frequently used in the therapy of lymphoma. Since lymphoma, for example Hodgkin’s disease, frequently affect rather young patients, the induction of secondary cancer or other long-term adverse effects after irradiation are important issues to deal with. Especially for mediastinal manifestations numerous organs and substructures at risk play a role. The heart, its coronary vessels and cardiac valves, the lungs, the thyroid and, for female patients, the breast tissue are only the most important organs at risk. In this study we investigated if proton-radiotherapy might reduce the dose delivered to the organs at risk and thus minimize the therapy-associated toxicity.

Methods

In this work we compared the dose delivered to the heart, its coronary vessels and valves, the lungs, the thyroid gland and the breast tissue by different volumetric photon plans and a proton plan, all calculated for a dose of 28.8 Gy (EURO-NET-PHL-C2). Target Volumes have been defined by F18-FDG PET-positive areas, following a modified involved node approach. Data from ten young female patients with mediastinal lymphoma have been evaluated. Three different modern volumetric IMRT (VMAT) photon plans have been benchmarked against each other and against proton-irradiation concepts. For plan-evaluation conformity- and homogeneity-indices have been calculated as suggested in ICRU 83. The target volume coverage as well as the dose to important organs at risk as the heart with its substructures, the lungs, the breast tissue, the thyroid and the spinal cord were calculated and compared. For statistical evaluation mean doses to organs at risk were evaluated by non- parametric Kruskal-Wallis calculations with pairwise comparisons.

Results

Proton-plans and three different volumetric photon-plans have been calculated. Proton irradiation results in significant lower doses delivered to organ at risk. The median doses and the mean doses could be decreased while PTV coverage is comparable. As well conformity as homogeneity are slightly better for proton plans. For several organs a risk reduction for secondary malignancies has been calculated using literature data as reference.

According to the used data derived from literature especially the secondary breast cancer risk, the secondary lung cancer risk and the risk for ischemic cardiac insults can be reduced significantly by using protons for radiotherapy of mediastinal lymphomas.

Conclusion

Irradiation with protons for mediastinal Hodgkin-lymphoma results in significant lower doses for almost all organs at risk and is suitable to reduce long term side effects for pediatric and adolescent patients.

Electronic supplementary material

The online version of this article (10.1186/s13014-019-1360-7) contains supplementary material, which is available to authorized users.

Clinical Intensity Modulated Proton Therapy for Hodgkin Lymphoma: Which Patients Benefit the Most?

PURPOSE

Radiation therapy (RT) improves control of Hodgkin lymphoma (HL), but patients who undergo RT are at risk for late effects, including cardiovascular disease and second cancers, because of radiation doses to organs at risk (OARs). Proton therapy (PT) can reduce OAR doses compared with conventional photon RT. However, access to PT is currently limited, so referrals must be appropriately selective. We aimed to identify subgroups of patients with HL who could benefit the most dosimetrically from RT with PT based on the prechemotherapy disease characteristics.

METHODS AND MATERIALS

Normal tissue radiation doses were calculated for 21 patients with HL who were treated with deep-inspiration breath-hold pencil-beam scanning (PBS) PT and compared with doses from 3-dimensional conformal (3D-CRT) and partial arc volumetric modulated (PartArc) photon RT. Prechemotherapy disease characteristics associated with significant dosimetric benefits from PBS compared with photon RT were identified.

RESULTS

Treatment with PBS was well tolerated and provided with good local control. PBS provided dosimetric advantages for patients whose clinical treatment volume extended below the seventh thoracic level and for female patients with axillary disease. In addition, an increasing dosimetric benefit for some OARs was observed for increasing target volume. PBS significantly reduced the mean dose to the heart, breast, lungs, spinal cord, and esophagus. Dose homogeneity and conformity within the target volume were also superior with PBS, but some high-dose measures and hot spots were increased with PBS compared with partial arc volumetric modulated photon RT.

CONCLUSIONS

PBS gives good target coverage and local control while providing reductions in radiation dose to OARs for individuals who receive RT for HL compared with advanced photon RT. Our findings highlight groups of patients who would be expected to gain more dosimetric benefit from PBS. These findings facilitate the selection of patients who should be considered a priority for PT.

Does deep inspiration breath hold reduce plan complexity? Multicentric experience of left breast cancer radiotherapy with volumetric modulated arc therapy

PURPOSE

Volumetric modulated arc therapy (VMAT) for left breast treatments allows heart sparing without compromising PTV coverage. However, this technique may require highly complex plans. Deep Inspiration Breath Hold (DIBH) procedure increases the heart-to-breast distance, facilitating the dose sparing of the heart. The aim of the present work was to investigate if the cardiac-sparing benefits of the DIBH technique were achieved with lower plan modulation and complexity than Free Breathing (FB) treatments.

METHODS AND MATERIALS

Ten left side breast cases were considered by two centers with different treatment planning systems (TPS) and Linacs. VMAT plans were elaborated in FB and DIBH according to the same protocol. Plan complexity was evaluated by scoring several complexity indices. A new global score index accounting for both plan quality and dosimetric parameters was defined. Pre-treatment QA was performed for all VMAT plans using EPID and Epiqa software.

RESULTS

DIBH-VMAT plans were associated with significant PTV coverage improvement and mean heart dose reduction (p < 0.003), increasing the resulting global score index. All the evaluated complexity indices showed lower plan complexity for DIBH plans than FB ones, but only in few cases the results were statistically significant. All plans passed the gamma analysis with the selected criteria.

CONCLUSIONS

The DIBH technique is superior to the FB technique when the heart needs further sparing, allowing a reduction of the doses to OARs with a slightly lower degree of plan complexity and without compromising plan deliverability. These benefits were achieved regardless of the technological scenarios adopted.

Role of Radiation Therapy in Patients With Relapsed/Refractory Diffuse Large B-Cell Lymphoma: Guidelines from the International Lymphoma Radiation Oncology Group

Approximately 30% to 40% of patients with diffuse large B-cell lymphoma (DLBCL) will have either primary refractory disease or relapse after chemotherapy. In transplant-eligible patients, those with disease sensitive to salvage chemotherapy will significantly benefit from high-dose therapy with autologous stem cell transplantation. The rationale for considering radiation therapy (RT) for selected patients with relapsed/refractory DLBCL as a part of the salvage program is based on data regarding the patterns of relapse and retrospective series showing improved local control and clinical outcomes for patients who received peritransplant RT. In transplant-ineligible patients, RT can provide effective palliation and, in selected cases, be administered with curative intent if the relapsed/refractory disease is localized. We have reviewed the indications for RT in the setting of relapsed/refractory DLBCL and provided recommendations regarding the optimal timing of RT, dose fractionation scheme, and treatment volume in the context of specific case scenarios.

Probability of carcinogenesis due to involved field and involved site radiation therapy techniques for supra- and infradiaphragmatic Hodgkin's disease

PURPOSE

To estimate the second cancer risk associated with Hodgkin Lymphoma (HL) radiotherapy at supradiaphragmatic or infradiaphragmatic region, using the involved field (IFRT) and the involved site radiotherapy (ISRT).

MATERIALS AND METHODS

IFRT and ISRT treatment plans were created for twenty HL patients. Three dimensional plans (3DRT) were employed for all patients. The organ equivalent dose (OED) and lifetime attributable risk (LAR) for organs at risk were estimated with mechanistic, plateau and bell-shaped model. Estimated risk values were compared with nominal risk of unexposed population.

RESULTS

For supradiaphragmatic radiotherapy, the mean OED range was 0.63-8.53 Gy and 0.63-7.26 Gy for IFRT and ISRT, respectively. The corresponding range for infradiaphragmatic radiotherapy was 0.18-7.64 Gy and 0.80-4.95 Gy. The LAR for cancer induction in the partially in field organs at risk after IFRT was 0.5%-8.0% and 0.2%-9.3% at supradiaphragmatic and infradiaphragmatic regions, respectively. The corresponding risk after ISRT method was 0.5%-5.2% and 0.9%-6.0%. Estimated cancer risk for breast, lung, thyroid, colon and rectal with ISRT was found significantly reduced compared to IFRT. The risk of secondary malignancies for lung, mouth, pharynx, rectum and colon was assessed more than 1.2 times higher than nominal risk for IFRT. The respective risk using ISRT was above nominal only for pharyngeal cancer.

CONCLUSION

ISRT compared with IFRT, results in decreased second cancer risk in most organs considered. Second cancer probability with IFRT was higher than the nominal risk for certain organs, while for ISRT remains higher only for pharyngeal cancer.

Volume effects of radiotherapy on the risk of second primary cancers: A systematic review of clinical and epidemiological studies

As modern radiotherapy, including intensity-modulated techniques, is associated with high dose gradients to normal tissues and large low-to-moderate dose volumes, the assessment of second primary cancer (SPC) risks requires quantification of dose-volume effects. We conducted a systematic review of clinical and epidemiological studies investigating the effect of the irradiated volume or dose-volume distribution to the remaining volume at risk (RVR) on SPC incidence. We identified eighteen studies comparing SPC risks according to the irradiated volume (i.e., in most studies, the size or number of fields used), and four studies reporting risk estimates according to the dose distribution to the RVR (after whole-body dose reconstruction). An increased risk of SPCs (mainly breast and lung cancers) with extended radiotherapy was observed among patients treated for Hodgkin lymphoma or childhood cancers. However, normal tissue dose distribution was not estimated, limiting the interpretation of those results in terms of volume effects on organs at risk. Studies considering whole-body exposures quantified dose-response relationships for point dose estimates, without accounting for dose-volume distributions. Therefore, they disregarded possible tissue effects (e.g. bystander and abscopal effects, stem cell repopulation) which may play a role in the induction of SPCs. Currently, there is no clinical or epidemiological information about a possible role of high dose gradients in surrounding organs, or increasing volumes of distant tissues exposed to low doses, in the risk of SPCs. Opportunities for future research nevertheless now exist, since methods and tools for estimating individual whole-body dose-volume distributions in large patient populations have been developed.

Proton versus photon deep inspiration breath hold technique in patients with hodgkin lymphoma and mediastinal radiation : A PLANNING COMPARISON OF DEEP INSPIRATION BREATH HOLD INTENSITY MODULATION RADIOTHERAPY AND INTENSITY MODULATED PROTON THERAPY

BACKGROUND

The benefits of proton therapy in the treatment of patients with Hodgkin lymphoma (HL) are controversially discussed. Therefore we compared intensitiy modulated proton therapy (IMPT) with intensity modulated radiotherapy (IMRT), in the form of volumetric modulated arc therapy (VMAT) in patients with Hodgkin lymphoma (HL), through a comparative treatment planning study.

METHODS

Radiation plans for 21 patients with Hodgkin Lymphoma (HL) were computed for IMPT and deep inspiration breath hold (DIBH) VMAT. Plans were optimized and computed assuming deep inspiration breath holding conditions. Dosimetric comparison on standard metrics from dose volume histograms was performed to appraise the relative merits of the two techniques, while proton plan robustness was assessed by re-computing the dose distribution of each plan by varying the Hounsfield Units to stopping power calibration by applying a ± 3 and 4% error.

RESULTS

DIBH-VMAT and IMPT both provided excellent coverage, conformity and heterogeneity of the clinical target volume (CTV) and planning target volume (PTV). IMPT reduced mean doses to the breasts, lungs, heart and normal tissue by 38-83%. IMPT significantly reduced mean doses to the heart to < 5 Gy despite bulky mediastinal disease and decreased breast doses in female patients to < 1 Gy. Despite the simulated 3 and 4% miscalibration errors, no remarkable or measurable impact was observed on the organs at risk (OARs).

CONCLUSIONS

This is the first comparison between DIBH-VMAT and IMPT in HL treatment. We could demonstrate statistically significant decreases in all dose/volume metrics of the OARs. Regardless of the planning paradigm used, range uncertainties can substantially under dose the PTV, while perhaps not leading to clinically significant deterioration of CTV coverage. With the geometry applied no impact was observed for OARs, suggesting IMPT as a superior technique for potentially reducing future health risks for HL patients.

Treatment of classical Hodgkin lymphoma in the era of brentuximab vedotin and immune checkpoint inhibitors

The majority of Hodgkin lymphoma patients are now cured with conventional first-line therapy; however, 10-15% of early-stage disease and less than 30% of advanced-stage patients are refractory(rare) or relapsed. Salvage second-line therapy combined with high-dose therapy and autologous stem-cell transplantation can cure 40-50% of patients. Recently novel agents (Brentuximab Vedotin and Immune Checkpoint inhibitors) have demonstrated evidence of therapeutic activity and are potential bridge to an allogeneic stem-cell transplantation. The review is aimed to present not only salvage strategies; indeed, the paper contains paragraphs about therapy and new treatment options at diagnosis.

The Role of Radiation Therapy in Patients With Relapsed or Refractory Hodgkin Lymphoma: Guidelines From the International Lymphoma Radiation Oncology Group

Relapsed and refractory Hodgkin lymphoma (HL) challenges clinicians to devise treatment strategies that are effective and safe. This problem is particularly prominent in an era when de-escalation trials are designed to minimize therapeutic toxicities in both early- and advanced-stage disease. Radiation therapy is the single most effective treatment modality for HL, and its integration into salvage regimens, or its independent use in select patients, must be understood to maximize our success in treating these patients. The complexity of treating relapsed or refractory HL derives from the spectrum of primary treatment approaches currently in use that creates heterogeneity in both treatment exposure and the potential toxicities of salvage therapy. Patients can have relapsed or refractory disease after limited or aggressive primary therapy (with or without radiation therapy), at early or delayed time points, with limited or extensive disease volumes, and with varying degrees of residual morbidity from primary therapy. Their response to salvage systemic therapy can be partial or complete, and the use of consolidative stem cell transplantation is variably applied. New biologics and immunotherapeutic approaches have broadened but also complicated salvage treatment approaches. Through all of this, radiation therapy remains an integral component of treatment for many patients, but it must be used effectively and judiciously. The purpose of this review is to describe the different treatment scenarios and provide guidance for radiation dose, volume, and timing in patients with relapsed or refractory HL.

Critical appraisal of the role of volumetric modulated arc therapy in the radiation therapy management of breast cancer

Background

The aim of this review is the critical appraisal of the current use of volumetric modulated arc therapy for the radiation therapy management of breast cancer. Both clinical and treatment planning studies were investigated.

Material and methods

A Pubmed/MEDLINE search of the National Library of Medicine was performed to identify VMAT and breast related articles. After a first order rejection of the irrelevant findings, the remaining articles were grouped according to two main categories: clinical vs. planning studies and to some sub-categories (pointing to significant technical features). Main areas of application, dosimetric and clinical findings as well as areas of innovations were defined.

Results

A total of 131 articles were identified and of these, 67 passed a first order selection. Six studies reported clinical results while 61 treatment dealed with treatment planning investigations. Among the innovation lines, the use of high intensity photon beams (flattening filter free), altered fractionation schemes (simultaneous integrated boost, accelerated partial breast irradiation, single fraction), prone positioning and modification of standard VMAT (use of dynamic trajectories or hybrid VMAT methods) resulted among the main relevant fields of interest. Approximately 10% of the publications reported upon respiratory gating in conjunction with VMAT.

Conclusions

The role of VMAT in the radiation treatment of breast cancer seems to be consolidated in the in-silico arena while still limited evidence and only one phase II trial appeared in literature from the clinical viewpoint. More clinical reports are needed to fully proove the expected dosimetric benefits demonstrated in the planning investigations.

Life years lost attributable to late effects after radiotherapy for early stage Hodgkin lymphoma: The impact of proton therapy and/or deep inspiration breath hold

BACKGROUND AND PURPOSE

Due to the long life expectancy after treatment, the risk of late effects after radiotherapy (RT) is of particular importance for patients with Hodgkin lymphoma (HL). Both deep inspiration breath hold (DIBH) and proton therapy have been shown to reduce the dose to normal tissues for mediastinal HL, but the impact of these techniques in combination is unknown. The purpose of this study was to compare the life years lost (LYL) attributable to late effects after RT for mediastinal HL using intensity modulated radiation therapy (IMRT) in free breathing (FB) and DIBH, and proton therapy in FB and DIBH.

MATERIALS AND METHODS

Plans for each technique were created for 22 patients with HL. Doses were extracted and the risk of late effects and LYL were estimated.

RESULTS

We found that the use of DIBH, proton therapy, and the combination significantly reduced the LYL compared to IMRT in FB. The lowest LYL was found for proton therapy in DIBH. However, when IMRT in DIBH was compared to proton therapy in FB, no significant difference was found.

CONCLUSIONS

Patient-specific plan comparisons should be used to select the optimal technique when comparing IMRT in DIBH and proton therapy in FB.

Optimal Therapy for Early-Stage Hodgkin's Lymphoma: Risk Adapting, Response Adapting, and Role of Radiotherapy

PURPOSE OF REVIEW

The aim of this article is to discuss the current role of radiotherapy (RT) for early-stage Hodgkin's lymphoma (HL) in the context of risk-adapted and response-adapted treatment strategy, and describe changes in RT technical approach.

RECENT FINDINGS

In low-risk patients, RT could be omitted but, at the price of a lower progression-free survival, and its role is still debated. Ongoing trials are combining new agents with chemotherapy alone or response-adapted combined modality therapy, and results are awaited. Modern RT incorporates lower doses and smaller fields, together with the implementation of sophisticated delivery techniques aimed to reducing the dose to critical structures such as the heart. The role of RT for early-stage HL is still under debate, and new combinations are emerging; an individualized approach should be recommended, considering all RT technical opportunities to minimize toxicity while maintaining efficacy.

Late Cardiac Toxicity After Mediastinal Radiation Therapy for Hodgkin Lymphoma: Contributions of Coronary Artery and Whole Heart Dose-Volume Variables to Risk Prediction

PURPOSE

Mediastinal radiation therapy (RT) for Hodgkin lymphoma (HL) is associated with late cardiotoxicity, but there are limited data to indicate which dosimetric parameters are most valuable for predicting this risk. This study investigated which whole heart dosimetric measurements provide the most information regarding late cardiotoxicity, and whether coronary artery dosimetry was more predictive of this outcome than whole heart dosimetry.

METHODS AND MATERIALS

A random sample of 125 HL patients treated with mediastinal RT was selected, and 3-dimensional cardiac dose-volume data were generated from historical plans using validated methods. Cardiac events were determined by linking patients to population-based datasets of inpatient and same-day hospitalizations and same-day procedures. Variables collected for the whole heart and 3 coronary arteries included the following: Dmean, Dmax, Dmin, dose homogeneity, V5, V10, V20, and V30. Multivariable competing risk regression models were generated for the whole heart and coronary arteries.

RESULTS

There were 44 cardiac events documented, of which 70% were ischemic. The best multivariable model included the following covariates: whole heart Dmean (hazard ratio [HR] 1.09, P=.0083), dose homogeneity (HR 0.94, P=.0034), male sex (HR 2.31, P=.014), and age (HR 1.03, P=.0049). When any adverse cardiac event was the outcome, models using coronary artery variables did not perform better than models using whole heart variables. However, in a subanalysis of ischemic cardiac events only, the model using coronary artery variables was superior to the whole heart model and included the following covariates: age (HR 1.05, P<.001), volume of left anterior descending artery receiving 5 Gy (HR 0.98, P=.003), and volume of left circumflex artery receiving 20 Gy (HR 1.03, P<.001).

CONCLUSION

In addition to higher mean heart dose, increasing inhomogeneity in cardiac dose was associated with a greater risk of late cardiac effects. When all types of cardiotoxicity were evaluated, the whole heart variable model outperformed the coronary artery models. However, when events were limited to ischemic cardiotoxicity, the coronary artery-based model was superior.

A case study evaluating deep inspiration breath-hold and intensity-modulated radiotherapy to minimise long-term toxicity in a young patient with bulky mediastinal Hodgkin lymphoma

Radiotherapy plays an important role in the treatment of early-stage Hodgkin lymphoma, but late toxicities such as cardiovascular disease and second malignancy are a major concern. Our aim was to evaluate the potential of deep inspiration breath-hold (DIBH) and intensity-modulated radiotherapy (IMRT) to reduce cardiac dose from mediastinal radiotherapy. A 24 year-old male with early-stage bulky mediastinal Hodgkin lymphoma received involved-site radiotherapy as part of a combined modality programme. Simulation was performed in free breathing (FB) and DIBH. The target and organs at risk were contoured on both datasets. Free breathing-3D conformal (FB-3DCRT), DIBH-3DCRT, FB-IMRT and DIBH-IMRT were compared with respect to target coverage and doses to organs at risk. A 'butterfly' IMRT technique was used to minimise the low-dose bath. In our patient, both DIBH (regardless of mode of delivery) and IMRT (in both FB and DIBH) achieved reductions in mean heart dose. DIBH improved all lung parameters. IMRT reduced high dose (V20), but increased low dose (V5) to lung. DIBH-IMRT was chosen for treatment delivery. Advanced radiotherapy techniques have the potential to further optimise the therapeutic ratio in patients with mediastinal lymphoma. Benefits should be assessed on an individualised basis.

Volumetric-modulated arc therapy (VMAT) versus 3D-conformal radiation therapy in supra-diaphragmatic Hodgkin's Lymphoma with mediastinal involvement: A dosimetric comparison

PURPOSE

To compare volumetric-modulated arc therapy (VMAT) with 3D-conformal radiation therapy (3D-CRT) mediastinal irradiation for stage I-II supra-diaphragmatic Hodgkin's Lymphoma (HL).

PATIENTS AND METHODS

Eleven patients were planned for RT after 4-6 cycles of ABVD chemotherapy: conventional 3D-CRT (AP/PA) and VMAT plans were conformed to the same PTV. Objective was to choose the best PTV coverage plan with the least OAR dose. The 2 plans were compared for: PTV coverage, mean dose and V5,V20lung, mean dose and V30heart, V5, V10, V15breast (female patients), and the integral body dose.

RESULTS

Both techniques achieved adequate PTV coverage. Mean lung and heart dose was consistently lower in VMAT plans. The lung V20 dose was acceptable for VMAT, but exceeded the tolerance threshold in 6 cases with 3DCRT plans. A mean difference of 15.9% for both lungs V20 favored VMAT plans; average MLD difference was 2.3Gy less for VMAT plans. Similarly, lower maximum and mean heart doses with a 3.3Gy dose reduction and a 9.4% difference in V30 favored VMAT plans. Mean V5lung/female breast and integral dose were invariably higher in VMAT plans because of the low-dose spread.

CONCLUSIONS

VMAT is a valuable technique for treatment of large mediastinal HL. VMAT spares the lung and heart compared to 3DCRT using ISRT in select HL cases. VMAT allows dose escalation for post-chemotherapy residual disease with minimal dose to OARs. VMAT low radiation dose (V5) to the normal tissues, and the increased integral dose should be considered.

Treatment of Early-Stage Unfavorable Hodgkin Lymphoma: Efficacy and Toxicity of 4 Versus 6 Cycles of ABVD Chemotherapy With Radiation

PURPOSE

The German Hodgkin Study Group HD11 trial validated 4 cycles of doxorubicin, bleomycin, vinblastine, dacarbazine (ABVD) chemotherapy followed by involved field radiation therapy (IFRT) for early unfavorable Hodgkin lymphoma (HL) patients. However, practitioners often recommend 6 cycles followed by RT, especially for bulky disease. We compared patient outcomes after treatment with 4 or 6 cycles of ABVD followed by RT (IFRT and involved site RT [ISRT]).

METHODS AND MATERIALS

We identified 128 patients treated for early unfavorable HL (GHSG criteria) between 2000 and 2013. Clinical outcomes (overall survival [OS] and freedom from relapse [FFR]) were estimated using Kaplan-Meier analysis. Toxicities were evaluated.

RESULTS

The median follow-up time was 5.0 years. Patients received 4 (70 patients, 55%) or 6 (58 patients, 45%) cycles of chemotherapy. Bulky disease was present in 22 patients (31%; 0 stage IA, 3 stage IB, 19 stage IIA) of the 4-cycle group and 42 patients (72%; 5 stage IA, 3 stage IB, 34 stage IIA) of the 6-cycle group. For patients receiving 4 and 6 cycles, the 6-year OS was 100% and 97% (P=.35), respectively, and the 6 year FFR was 100% and 98% (P=.28), respectively. More patients received 6 cycles if they were treated before 2010 (HD11 report) (P=.01) and if they had bulky disease (P<.01). Sixty-eight percent of patients received ISRT. The 6-year FFR was 99% and 100% for patients receiving ISRT and IFRT, respectively (P=.58). More patients experienced bleomycin pulmonary toxicity in the 6-cycle group (20% vs 31%, P=.16). For patients with bulky disease, the 4-year FFR was similar with receipt of 4 (100%) or 6 (98%) cycles (P=.48) and IFRT (100%) or ISRT (98%) (P=.52). There were no deaths among patients with bulky disease.

CONCLUSIONS

Patients with early unfavorable HL have excellent outcomes with 4 cycles of ABVD chemotherapy followed by ISRT. Six cycles of chemotherapy does not appear superior for disease control, even for bulky disease.

Evolution of radiation techniques in the treatment of mediastinal lymphoma: from 3D conformal radiotherapy (3DCRT) to intensity-modulated RT (IMRT) using helical tomotherapy (HT): a single-centre experience and review of the literature

OBJECTIVE

To evaluate radiation techniques and their toxicity in the treatment of Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL) with mediastinal disease over a 10-year period.

METHODS

Between 2003 and 2015, 173 patients with Stage I-III nodal lymphoma were treated in our institution: some of these patients were irradiated for HL or NHL with mediastinal disease. Some of the patients were treated by three-dimensional conformal radiotherapy (3DCRT), others by intensity-modulated radiotherapy (IMRT).

RESULTS

We studied 26 males and 43 females with a median age of 26 years. The median follow-up was 43 months. 49 patients were treated by 3DCRT and 20 patients by IMRT. The median dose received by patients treated for NHL was 40 Gy (range: 36-44 Gy), and the median dose received by patients with HL was 30 Gy (range: 30-36 Gy). Between 2003 and 2006, 16 patients were treated by 3DCRT vs 0 patients by IMRT. Between 2007 and 2009, 16 patients received 3DCRT and one patient received IMRT. Between 2010 and 2015, 19 patients received IMRT, and no patients received 3DCRT. 11 of the 20 (55%) patients treated by IMRT and 35 of the 49 (71.4%) patients treated by 3DCRT experienced acute toxicity. Among the patients treated by 3DCRT, one patient experienced Grade 1 radiation pneumonitis and two patients experienced Grade 1 acute mucositis. No late toxicity was observed in patients treated by IMRT.

CONCLUSION

Improvement of radiation techniques for HL and NHL appears to have improved acute and late clinical safety. Longer follow-up is necessary to evaluate very late toxicity.

ADVANCES IN KNOWLEDGE

Improvement of radiation techniques for HL and NHL appears to improve the tolerance.