Predictors of Hypothyroidism in Hodgkin Lymphoma Survivors After Intensity Modulated Versus 3-Dimensional Radiation Therapy

Late endocrine diseases in survivors of adolescent and young adult cancer in California: a population-based study

BACKGROUND

Cancer survivors have increased risk of endocrine complications, but there is a lack of information on the occurrence of specific endocrinopathies at the population-level.

METHODS

We used data from the California Cancer Registry (2006-2018) linked to statewide hospitalisation, emergency department, and ambulatory surgery databases. We estimated the cumulative incidence of and factors associated with endocrinopathies among adolescents and young adults (AYA, 15-39 years) who survived ≥2 years after diagnosis.

RESULTS

Among 59,343 AYAs, 10-year cumulative incidence was highest for diabetes (4.7%), hypothyroidism (4.6%), other thyroid (2.2%) and parathyroid disorders (1.6%). Hypothyroidism was most common in Hodgkin lymphoma, leukaemia, breast, and cervical cancer survivors, while diabetes was highest among survivors of leukaemias, non-Hodgkin lymphoma, colorectal, cervical, and breast cancer. In multivariable models, factors associated with increased hazard of endocrinopathies were treatment, advanced stage, public insurance, residence in low/middle socioeconomic neighbourhoods, older age, and non-Hispanic Black or Hispanic race/ethnicity. Haematopoietic cell transplant was associated with most endocrinopathies, while chemotherapy was associated with a higher hazard of ovarian dysfunction and hypothyroidism.

CONCLUSIONS

We observed a high burden of endocrinopathies among AYA cancer survivors, which varied by treatment and social factors. Evidence-based survivorship guidelines are needed for surveillance of these diseases.

Hypothyroidism following Radiotherapy for Head and Neck Cancer: A Systematic Review of the Literature and Opportunities to Improve the Therapeutic Ratio

(1) Background: Radiotherapy (RT) is a central component for the treatment of many head and neck cancers. In this systematic review of the literature, we aimed to characterize and quantify the published evidence on RT-related hypothyroidism, including estimated incidence, clinical risk factors, and dosimetric parameters that may be used to guide clinical decision making. Furthermore, we aimed to identify potential areas of improvement in the prevention and clinical management of RT-induced hypothyroidism, including the role of modern advanced therapeutic techniques. (2) Methods: We conducted a systemic review of the literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. PubMed and Google Scholar were searched to identify original research articles describing the incidence, mechanism, dosimetry, treatment, or prevention of radiation-related hypothyroidism for adults receiving RT for the treatment of head and neck cancers. The snowball method was used to identify additional articles. For identified articles, we tabulated several datapoints, including publication date, patient sample size, estimated hypothyroidism incidence, cancer site/type, follow-up period, radiation modality and technique, use of multimodality therapy, method of thyroid function evaluation, and proposed dosimetric predictors of hypothyroidism. (3) Results: One hundred and eleven articles met inclusion criteria, reflecting a range of head and neck cancer subtypes. There was a large variation in the estimated incidence of RT-related hypothyroidism, with a median estimate of 36% (range 3% to 79%). Reported incidence increased in later publication dates, which was likely related to improved screening and longer follow up. There were a wide variety of predictive metrics used to identify patients at high risk of hypothyroidism, the most common of which were volumetric and mean dosimetrics related to the thyroid gland (Vxx%, Dmean). More recently, there has been increasing evidence to suggest that the thyroid gland volume itself and the volume of the thyroid gland spared from high-dose radiation (VSxx) may better predict thyroid function after RT. There were no identified studies investigating the role of advanced radiotherapeutic techniques such as MRI-guided RT or particle therapy to decrease RT-related hypothyroidism. Conclusions: Hypothyroidism is a common toxicity resulting from therapeutic radiation for head and neck cancer with recent estimates suggesting 40-50% of patients may experience hypothyroidism after treatment. Dosimetric predictive models are increasingly able to accurately identify patients at risk of hypothyroidism, especially those utilizing thyroid VS metrics. Further investigation regarding the potential for advanced radiotherapeutic therapies to decrease RT-induced thyroid dysfunction is needed.

[Endocrine disorders after combined chemoradiotherapy in Hodgkin Lymphoma survivors]

BACKGROUND

Hodgkin's lymphoma (HL) is one of the most common malignant lymphoproliferative diseases. Chemotherapy and radiotherapy used in the treatment of LH induce a number of toxic effects leading to dysfunction of endocrine system. Hormonal disorders in HL and their relationships with the therapy used remain to be clarified.

AIM

To assess disorders of the endocrine function of thyroid, parathyroid glands and gonads in HL survivors.

MATERIALS AND METHODS

Screening of endocrine dysfunction of the thyroid, parathyroid glands and gonads was performed in 160 adult patients with HL, 55 men and 105 women, at remission stage induced by chemotherapy or chemoradiotherapy. Forty healthy subjects, matched by age, were acted as control. The levels of TSH, T3, free T4, PTH, FSH, LH, free testosterone, dehydroepiandrosterone sulfate (DHEA-S), and sex-hormone binding globulin (SHBG) were measured in blood serum by ELISA. Bone mineral density (BMD) was assessed by DEXA.

RESULTS

Hypothyroidism (25%), hyperparathyroidism (15.6%) and hypogonadism (29% of men and 25.3% of women) were the most prevalent endocrine disorders in LH survivors. Hypothyroidism was significantly more common in patients after chemoradiotherapy than in those who received only chemotherapy (χ2=9.4, р=0.002). In patients with hyperparathyroidism, there were negative correlations between PTH levels and BMD in the lumbar spine (r=-0.74, p=0.00002) and in the femoral neck (r=-0.66, p=0.0003). Men with HL demonstrated lower free testosterone concentrations when compared to control (p=0.04); LH and FSH levels were elevated (p=0.0004 and p=0.04, respectively). In men with HL the levels of DHEA-S were reduced (p=0.0009). The increased SHBG concentrations were revealed in 13 (23.6%) men. Women of reproductive age with HL had higher levels of LH in the luteal phase (p=0.05) and FSH in the follicular phase (p=0.02) than controls.

CONCLUSION

The data indicate a high prevalence of the dysfunctions of thyroid, parathyroid glands, and gonads in HL survivors. Screening for endocrine disorders in these patients is highly recommended.

Systematic review for deep inspiration breath hold in proton therapy for mediastinal lymphoma: A PTCOG Lymphoma Subcommittee report and recommendations

PURPOSE

To systematically review all dosimetric studies investigating the impact of deep inspiration breath hold (DIBH) compared with free breathing (FB) in mediastinal lymphoma patients treated with proton therapy as compared to IMRT (intensity-modulated radiation therapy)-DIBH.

MATERIALS AND METHODS

We conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline using the PubMed database to identify studies of mediastinal lymphoma patients with dosimetric comparisons of proton-FB and/or proton-DIBH with IMRT-DIBH. Parameters included mean heart (MHD), lung (MLD), and breast (MBD) doses, among other parameters. Case reports were excluded. Absolute differences in mean doses > 1 Gy between comparators were considered to be clinically meaningful.

RESULTS

As of April 2021, eight studies fit these criteria (n = 8), with the following comparisons: proton-FB vs IMRT-DIBH (n = 5), proton-DIBH vs proton-FB (n = 5), and proton-DIBH vs IMRT-DIBH (n = 8). When comparing proton-FB with IMRT-DIBH in 5 studies, MHD was reduced with proton-FB in 2 studies, was similar (<1 Gy difference) in 2 studies, and increased in 1 study. On the other hand, MLD and MBD were reduced with proton-FB in 3 and 4 studies, respectively. When comparing proton-DIBH with proton-FB, MHD and MLD were reduced with proton DIBH in 4 and 3 studies, respectively, while MBD remained similar. Compared with IMRT-DIBH in 8 studies, proton-DIBH reduced the MHD in 7 studies and was similar in 1 study. Furthermore, MLD and MBD were reduced with proton-DIBH in 8 and 6 studies respectively. Integral dose was similar between proton-FB and proton-DIBH, and both were substantially lower than IMRT-DIBH.

CONCLUSION

Accounting for heart, lung, breast, and integral dose, proton therapy (FB or DIBH) was superior to IMRT-DIBH. Proton-DIBH can lower dose to the lungs and heart even further compared with proton-FB, depending on disease location in the mediastinum, and organ-sparing and target coverage priorities.

Consolidative active scanning proton therapy for mediastinal lymphoma: selection criteria, treatment implementation and clinical feasibility

AIMS

Proton therapy (PT) represents an advanced form of radiotherapy with unique physical properties which could be of great advantage in reducing long-term radiation morbidity for cancer survivors. Here, we aim to describe the whole process leading to the clinical implementation of consolidative active scanning proton therapy treatment (PT) for mediastinal lymphoma.

METHODS

The process included administrative, technical and clinical issues. Authorization of PT is required in all cases as mediastinal lymphoma is currently not on the list of diseases reimbursable by the Italian National Health Service. Technically, active scanning PT treatment for mediastinal lymphoma is complex, due to the interaction between actively scanned protons and the usually irregular and large volumes to be irradiated, the nearby healthy tissues and the target motion caused by breathing. A road map to implement the technical procedures was prepared. The clinical selection of patients was of utmost importance and took into account both patient and tumor characteristics.

RESULTS

The first mediastinal lymphoma was treated at our PT center in 2018, four years after the start of the clinical activities. The treatment technique implementation included mechanical deep inspiration breath-hold simulation computed tomography (CT), clinical target volume (CTV)-based multifield optimization planning and plan robustness analysis. The ultimate authorization rate was 93%. In 4 cases a proton-photon plan comparison was required. Between May 2018 and February, 2021, 14 patients were treated with consolidative PT. The main clinical reasons for choosing PT over photons was a bulky disease in 8 patients (57%), patient's age in 11 patients (78%) and the proximity of the lymphoma to cardiac structures in 10 patients (71%). With a median follow-up of 15 months (range, 1-33 months) all patients but one (out-of-field relapse) are without evidence of disease, all are alive and no late toxicities were observed during the follow-up period.

CONCLUSIONS

The clinical implementation of consolidative active scanning PT for mediastinal lymphoma required specific technical procedures and a prolonged experience with PT treatments. An accurate selection of patients for which PT could be of advantage in comparison with photons is mandatory.

Predictors of radiation-induced hypothyroidism in nasopharyngeal carcinoma survivors after intensity-modulated radiotherapy

Background

The aim of the study is to identify clinical and dosimetric factors that could predict the risk of hypothyroidism in nasopharyngeal carcinoma (NPC) patients following intensity-modulated radiotherapy (IMRT).

Methods

A total of 404 non-metastatic NPC patients were included in our study. All patients were treated with IMRT. The thyroid function were performed for all patients before and after radiation at regular intervals. The time onset for developing hypothyroidism was defined as the time interval between the completion of RT and the first recorded abnormal thyroid hormone test. The cumulative incidence rates of hypothyroidism were estimated using Kaplan–Meier method. Univariate and multivariate Cox regression analyses were performed to detect the most promising factors that were associated with hypothyroidism.

Results

Median follow up was 60.6 months. The 3-, 5- and 7- year cumulative incidence rate of hypothyroidism was 39.4%, 49.1% and 54.7%, respectively. The median time to primary hypothyroidism and central hypothyroidism were 15.4 months (range 2.9–83.8 months) and 29.9 months (range 19.8–93.6 months), respectively. Univariate and multivariate analyses revealed that younger age, female gender and small thyroid volume were the most important factors in predicting the risk of hypothyroidism. Dtmean (mean dose of thyroid), V30-V50 (percentage of thyroid volume receiving a certain dose level) and VS45-VS60 (the absolute volumes of thyroid spared from various dose levels) remained statistically significant in multivariate analyses. Cutoff points of 45 Gy (Dtmean), 80% (Vt40) and 5 cm³ (VS45Gy) were identified to classify patients as high-risk or low-risk group.

Conclusion

Thyroid Vt40 highly predicted the risk of hypothyroidism after IMRT for NPC patients. We recommended plan optimization objectives to reduce thyroid Vt40 to 80%.

Trial registration: Retrospectively registered.

Late Endocrine and Metabolic Sequelae and Long-Term Monitoring of Classical Hodgkin Lymphoma and Diffuse Large B-Cell Lymphoma Survivors: A Systematic Review by the Fondazione Italiana Linfomi

Simple Summary

The aim of this systematic review, conducted by the researchers of Fondazione Italiana Linfomi (FIL), was to fill a gap in the literature regarding the follow-up of endocrine-metabolic sequelae in lymphoma patients five years and more after the end of treatments. These patients can develop a series of late toxicities, such as thyroid and gonadal dysfunctions, osteoporosis and metabolic syndrome, that contribute to comorbidity burden and could affect quality of life and overall survival. There are currently no specific indications for tailored screening programs and/or tertiary prevention for the subset of long-term lymphoma survivors treated with modern therapeutic approaches. This systematic review also aimed to understand whether there is sufficient evidence to plan modern, tailored screening programs and validated exams for the outcomes of interest based on the real incidence or prevalence of late endocrine and metabolic sequelae.

Abstract

Background: Overall survival after lymphoma has improved in recent years, but the high prevalence of late treatment-related sequelae has been observed as a counterpart. Method: In this systematic review, FIL researchers aimed to: (i) estimate the incidence or prevalence of late endocrine-metabolic sequelae, (ii) evaluate the effects of modern therapeutic approaches on incidence or prevalence of late endocrine-metabolic sequelae, and (iii) determine whether there is evidence of follow-up schemes for their screening/early diagnosis in the subset of long-term classical Hodgkin lymphoma (cHL) and diffuse large B-cell lymphoma (DLBCL) survivors treated at adult age. The MEDLINE, Embase and the Cochrane Library databases were searched for relevant articles published up to October, 2020. The study selection process was conducted by three independent reviewers and was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A risk of bias assessment was performed using the Cochrane tool for randomized trials and the Newcastle-Ottawa Scale for observational studies. Results: In the final analysis, eight studies were included, four of which focused on thyroid disease, two on gonadal dysfunction, one on bone disease and one on metabolic syndrome. Hypothyroidism was reported in up to 60% of adult cHL survivors and was frequently recorded even with modern radiotherapy approaches. Menopause occurred in 52–72% of women after chemotherapy. An 86% reduction in vertebral density was reported following R-CHOP-like chemotherapy. Sarcopenia and metabolic syndrome were reported in 37.9% and 60% of patients, respectively. No validated screening protocols were found for the early diagnosis of long-term treatment-related endocrine and metabolic sequelae, thus the authors finally suggest the execution of screening exams according to the risk category which were identified in the epidemiologic studies.

Risk of Benign and Malignant Thyroid Disorders in Subjects Treated for Paediatric/Adolescent Neoplasia: Role of Morphological and Functional Screening

Background: Patients treated for paediatric/adolescent (P/A) neoplasia have a high incidence of both benign and malignant thyroid diseases. Given the high incidence of sequelae, literature data show a clinical benefit of morpho-functional thyroid screening in paediatric/adolescent cancer survivors and a careful lifetime follow-up. Patients and methods: The incidence of thyroid alterations was evaluated in a consecutive series of 343 patients treated with chemotherapy (CHE) and radiotherapy (RTE) or only with CHE for P/A tumours between 1976 and 2018 (mean age at time of primary paediatric malignancy 7.8 ± 4.7 years). All patients underwent thyroidal morpho-functional evaluation between 2000 and 2019. Results: 178 patients (51.9%) were treated only with CHE and 165 (48.1%) with CHE+RTE. A functional and/or structural thyroid disease was diagnosed in 147 (42.5%; 24.2% in CHE and 62.4% in CHE+RTE group; p = 0.0001). Of note, 71 (20.7%) patients with no evidence of disease at first evaluation developed a thyroid alteration during the follow-up. Primitive hypothyroidism was diagnosed in 54 patients (15.7%; 11.2% in CHE vs. 20.6% in CHE+RTE group; p = 0.01) and hyperthyroidism in 4. Sixty-three patients developed thyroid nodules (18.4%; 4.0% in CHE and 14.1% in CHE+RTE group; p < 0.001); thyroid cancer was diagnosed in 30 patients (8.7%; 4.5% in CHE and 12.4% in CHE + RTE group; p = 0.007). Conclusions: In patients treated with CHE+RTE, the prevalence of hypothyroidism and nodular pathology, both malignant and benign, were significantly greater than in patients treated with CHE. However, also in the CHE group, the frequency of thyroid disease is not negligible and the pathogenetic mechanisms remain to be clarified. Our data suggest the clinical benefit of morpho-functional thyroid screening in P/A cancer survivors.

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.

MorbiNet Study: Hypothyroidism Comorbidity Networks in the Adult General Population

PURPOSE

Multimorbidity impacts quality of life. We constructed hypothyroidism comorbidity networks to identify positive and negative associations with other prevalent diseases.

METHODS

We analyzed data of 285 342 patients with hypothyroidism from 3 135 948 adults with multimorbidity in a population-based study in Catalonia, Spain, (period: 2006-2017). We constructed hypothyroidism comorbidity networks using logistic regression models, adjusted by age and sex, and for men and women separately. We considered relevant associations those with odds ratios (OR) >1.2 or <0.8 and P value < 1e-5 to identify coexistence greater (or smaller) than the expected by the prevalence of diseases. Multivariate models considering comorbidities were used to further adjust OR values.

RESULTS

The conditions associated included larynx cancer (adjusted OR: 2.48), congenital anomalies (2.26), thyroid cancer (2.13), hyperthyroidism (1.66), vitamin B12/folate deficiency anemia (1.57), and goiter (1.56). The network restricted to men had more connections (mental, cardiovascular, and neurological) and stronger associations with thyroid cancer (7.26 vs 2.55), congenital anomalies (5.11 vs 2.13), hyperthyroidism (4.46 vs 1.69), larynx cancer (3.55 vs 1.67), and goiter (3.94 vs 1.64). After adjustment for comorbidities, OR values were more similar in men and women. The strongest negative associations after adjusting for comorbidities were with HIV/AIDS (OR: 0.71) and tobacco abuse (0.77).

CONCLUSIONS

Networks show direct and indirect hypothyroidism multimorbidity associations. The strongest connections were thyroid and larynx cancer, congenital anomalies, hyperthyroidism, anemia, and goiter. Negative associations included HIV/AIDS and tobacco abuse. The network restricted to men had more and stronger associations, but not after adjusting for comorbidities, suggesting important indirect interactions.

Assessment of Radiation Doses Delivered to Organs at Risk Among Patients With Early-Stage Favorable Hodgkin Lymphoma Treated With Contemporary Radiation Therapy

IMPORTANCE

Response-adapted randomized trials have used positron emission tomography-computed tomography to attempt to identify patients with early-stage favorable Hodgkin lymphoma (ESFHL) who could be treated with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) without radiation therapy (RT). While maximal efficacy is demonstrated with combined modality therapy, RT is often omitted in fear of late adverse effects; however, the application of modern RT could limit these toxic effects.

OBJECTIVE

To determine the radiation doses delivered to organs at risk with modern involved-site RT among patients with ESFHL treated with 20 Gy after 2 cycles of ABVD.

DESIGN, SETTING, AND PARTICIPANTS

This case series included 42 adult patients with ESFHL (according to the German Hodgkin Study Group criteria) who were treated between 2010 and 2019, achieved complete response by positron emission tomography-computed tomography (1-3 on 5-point scale) following 2 cycles of ABVD, and then received consolidative RT. The study was conducted at a single comprehensive cancer center.

EXPOSURES

2 cycles of chemotherapy followed by 20-Gy involved-site RT.

MAIN OUTCOMES AND MEASURES

The medical records of patients with ESFHL were examined. Organs at risk were contoured, and doses were calculated. Progression-free survival, defined from date of diagnosis to disease progression, relapse, or death, and overall survival were estimated using the Kaplan-Meier method.

RESULTS

The cohort comprised 42 patients with ESFHL (median [range] age at diagnosis, 35 [18-74] years; 18 [43%] women; 24 [57%] with stage II disease). At a median follow-up of 44.6 (95% CI, 27.6-61.6) months, the 3-year progression-free survival and overall survival rates were 91.2% (95% CI, 74.9%-97.1%) and 97.0% (95% CI, 80.4%-99.6%), respectively. The mean heart dose was less than 5 Gy (mean, 0.8 Gy; SD, 1.5 Gy; range, 0-4.8 Gy) in all patients. The mean (SD) breast dose for both breasts was 0.1 (0.2) Gy (left breast range, 0-1.0 Gy; right breast range, 0-0.9 Gy).

CONCLUSIONS AND RELEVANCE

In this study, combined modality therapy with 2 cycles of ABVD and 20 Gy for ESFHL was highly effective and avoided excess doses to organs at risk, which may limit long-term toxic effects.

Optimized variable selection via repeated data splitting

Model selection in high-dimensional settings has received substantial attention in recent years, however, similar advancements in the low-dimensional setting have been lacking. In this article, we introduce a new variable selection procedure for low to moderate scale regressions (n>p). This method repeatedly splits the data into two sets, one for estimation and one for validation, to obtain an empirically optimized threshold which is then used to screen for variables to include in the final model. In an extensive simulation study, we show that the proposed variable selection technique enjoys superior performance compared with candidate methods (backward elimination via repeated data splitting, univariate screening at 0.05 level, adaptive LASSO, SCAD), being amongst those with the lowest inclusion of noisy predictors while having the highest power to detect the correct model and being unaffected by correlations among the predictors. We illustrate the methods by applying them to a cohort of patients undergoing hepatectomy at our institution.

Dosimetric Predictors of Acute and Chronic Alopecia in Primary Brain Cancer Patients Treated With Volumetric Modulated Arc Therapy

Purpose: To determine dose constraints that correlate with alopecia in patients treated with photon-based Volumetric Modulated Arc Therapy (VMAT) for primary brain tumors.

Methods: During the treatment planning process, the scalp was drawn as a region of interest. Dose received by 0.1 cc (D_0.1cc), mean dose (D_mean), absolute volumes receiving different doses (V_16Gy, V_20Gy, V_25Gy, V_30Gy, V_35Gy, V_40Gy, and V_43Gy) were registered for the scalp. Alopecia was assessed according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Receiver operating characteristics (ROC) curve analysis was used to identify parameters associated with hair-loss.

Results: One-hundred and one patients were included in this observational study. At the end of radiotherapy (RT), 5 patients did not develop alopecia (D_mean scalp 3.1 Gy). The scalp of the patients with G1 (n = 11) and G2 (n = 85) alopecia received D_mean of 10.6 Gy and 11.8 Gy, respectively. At ROC analysis, V_16Gy20Gy ≥ 5.2 cc were the strongest predictors of acute alopecia risk. Chronic hair-loss assessment was available for 74 patients: median time to recovery from G2 alopecia was 5, 9 months. The actuarial rate of hair regrowth was 98.1% at 18 months after the end of RT. At ROC analysis, V_40Gy43Gy ≥2.2 cc were the strongest predictors of chronic G2-alopecia risk. V_20Gy, V_40Gy, and D_0,1cc were shown to be independent variables according to correlation coefficient r.

Conclusions: V_20Gy and V_40Gy were the strongest predictors for acute and chronic G2 hair-loss, respectively. The low-dose bath typical of VMAT corresponds to large areas of acute but transient alopecia. However, the steep dose gradient of VMAT allows to reduce the areas of the scalp that receive higher doses, minimizing the risk of permanent alopecia.

The application of our dosimetric findings for the scalp may help in reducing the alopecia risk and also in estimating the probability of hair-loss during patient counseling before starting radiotherapy.

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.

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.

Normal tissue complication probability (NTCP) models for modern radiation therapy

Mathematical models of normal tissue complication probability (NTCP) able to robustly predict radiation-induced morbidities (RIM) play an essential role in the identification of a personalized optimal plan, and represent the key to maximizing the benefits of technological advances in radiation therapy (RT). Most modern RT techniques pose, however, new challenges in estimating the risk of RIM. The aim of this report is to schematically review NTCP models in the framework of advanced radiation therapy techniques. Issues relevant to hypofractionated stereotactic body RT and ion beam therapy are critically reviewed. Reirradiation scenarios for new or recurrent malignances and NTCP are also illustrated. A new phenomenological approach to predict RIM is suggested.

Auto- versus human-driven plan in mediastinal Hodgkin lymphoma radiation treatment

Background

Technological advances in Hodgkin lymphoma (HL) radiation therapy (RT) by high conformal treatments potentially increase control over organs-at-risk (OARs) dose distribution. However, plan optimization remains a time-consuming task with great operator dependent variability. Purpose of the present study was to devise a fully automated pipeline based on the Pinnacle³ Auto-Planning (AP) algorithm for treating female supradiaphragmatic HL (SHL) patients.

Methods

CT-scans of 10 female patients with SHL were considered. A “butterfly” (BF) volumetric modulated arc therapy was optimized using SmartArc module integrated in Pinnacle³ v. 9.10 using Collapsed Cone Convolution Superposition algorithm (30 Gy in 20 fractions). Human-driven (Manual-BF) and AP-BF optimization plans were generated. For AP, an optimization objective list of Planning Target Volume (PTV)/OAR clinical goals was first implemented, starting from a subset of 5 patients used for algorithm training. This list was then tested on the remaining 5 patients (validation set). In addition to the BF technique, the AP engine was applied to a 2 coplanar disjointed arc (AP-ARC) technique using the same objective list. For plan evaluation, dose-volume-histograms of PTVs and OARs were extracted; homogeneity and conformity indices (HI and CI), OARs dose-volume metrics and odds for different toxicity endpoints were computed. Non-parametric Friedman and Dunn tests were used to identify significant differences between groups.

Results

A single AP objective list for SHL was obtained. Compared to the manual plan, both AP-plans offer comparable CIs while AP-ARC also achieved comparable HIs. All plans fulfilled the clinical dose criteria set for OARs: both AP solutions performed at least as good as Manual-BF plan. In particular, AP-ARC outperformed AP-BF in terms of heart sparing involving a lower risk of coronary events and radiation-induced lung fibrosis. Hands-on planning time decreased by a factor of 10 using AP on average.

Conclusions

Despite the high interpatient PTV (size and position) variability, it was possible to set a standard SHL AP optimization list with a high level of generalizability. Using the implemented list, the AP module was able to limit OAR doses, producing clinically acceptable plans with stable quality without additional user input. Overall, the AP engine associated to the arc technique represents the best option for SHL.

Proton therapy for adults with mediastinal lymphomas: the International Lymphoma Radiation Oncology Group guidelines

Among adult lymphoma survivors, radiation treatment techniques that increase the excess radiation dose to organs at risk (OARs) put patients at risk for increased side effects, especially late toxicities. Minimizing radiation to OARs in adults patients with Hodgkin and non-Hodgkin lymphomas involving the mediastinum is the deciding factor for the choice of treatment modality. Proton therapy may help to reduce the radiation dose to the OARs and reduce toxicities, especially the risks for cardiac morbidity and second cancers. Because proton therapy may have some disadvantages, identifying the patients and the circumstances that may benefit the most from proton therapy is important. We present modern guidelines to identify adult lymphoma patients who may derive the greatest benefit from proton therapy, along with an analysis of the advantages and disadvantages of proton treatment.