Tolerance of normal tissue to therapeutic irradiation

Correlation of Regional Lung Ventilation and Gas Transfer to Red Blood Cells: Implications for Functional-Avoidance Radiation Therapy Planning

PURPOSE

To investigate the degree to which lung ventilation and gas exchange are regionally correlated, using the emerging technology of hyperpolarized (HP)-129Xe magnetic resonance imaging (MRI).

METHODS AND MATERIALS

Hyperpolarized-129Xe MRI studies were performed on 17 institutional review board-approved human subjects, including 13 healthy volunteers, 1 emphysema patient, and 3 non-small cell lung cancer patients imaged before and approximately 11 weeks after radiation therapy (RT). Subjects inhaled 1 L of HP-129Xe mixture, followed by the acquisition of interleaved ventilation and gas exchange images, from which maps were obtained of the relative HP-129Xe distribution in three states: (1) gaseous, in lung airspaces; (2) dissolved interstitially, in alveolar barrier tissue; and (3) transferred to red blood cells (RBCs), in the capillary vasculature. The relative spatial distributions of HP-129Xe in airspaces (regional ventilation) and RBCs (regional gas transfer) were compared. Further, we investigated the degree to which ventilation and RBC transfer images identified similar functional regions of interest (ROIs) suitable for functionally guided RT. For the RT patients, both ventilation and RBC functional images were used to calculate differences in the lung dose-function histogram and functional effective uniform dose.

RESULTS

The correlation of ventilation and RBC transfer was ρ = 0.39 ± 0.15 in healthy volunteers. For the RT patients, this correlation was ρ = 0.53 ± 0.02 before treatment and ρ = 0.39 ± 0.07 after treatment; for the emphysema patient it was ρ = 0.24. Comparing functional ROIs, ventilation and RBC transfer demonstrated poor spatial agreement: Dice similarity coefficient = 0.50 ± 0.07 and 0.26 ± 0.12 for the highest-33%- and highest-10%-function ROIs in healthy volunteers, and in RT patients (before treatment) these were 0.58 ± 0.04 and 0.40 ± 0.04. The average magnitude of the differences between RBC- and ventilation-derived functional effective uniform dose, fV20Gy, fV10Gy, and fV5Gy were 1.5 ± 1.4 Gy, 4.1% ± 3.8%, 5.0% ± 3.8%, and 5.3% ± 3.9%, respectively.

CONCLUSION

Ventilation may not be an effective surrogate for true regional lung function for all patients.

Multivariate normal tissue complication probability modeling of vaginal late toxicity after brachytherapy for cervical cancer

PURPOSE

To explore the best variables combination for a predictive model of vaginal toxicity in cervical cancer patients undergoing brachytherapy (BT).

METHODS AND MATERIALS

Clinical and 3-dimensional dosimetric parameters were retrospectively extracted from an institutional database of consecutive patients undergoing intracavitary BT after external beam radiation therapy from 2006 to 2013 for a cervical cancer. A least absolute shrinkage and selection operator selection procedure in Cox's proportional hazards regression model was performed to select a set of relevant predictors for a multivariate normal tissue complication probability model of Grade ≥2 vaginal late toxicity. Outcomes reliability was internally assessed by bootstrap resampling method.

RESULTS

One hundred sixty-nine women were included in the present study with a median followup time of 3.8 years (interquartile range [IQR], 1.9-5.6 years). The 2 years and 5 years cumulative incidence rates of Grade ≥2 late vaginal toxicity were 19.9% and 27.5%, respectively. Among 31 metrics and six clinical factors extracted, the optimal model included two dosimetric variables: V70_Gy and D5_% (the percentage volume that received a dose greater or equal to 70 Gy and the minimum dose given to the hottest 5% volume, respectively). Area under the ROC curve at 2 and 5 years of followup were 0.85 and 0.91, respectively. Regarding internal validation, median area under the ROC curve of bootstrap predictions was 0.83 (IQR, 0.78-0.88) and 0.89 (IQR, 0.85-0.93) at 2 and 5 years of followup, respectively.

CONCLUSIONS

A multivariate normal tissue complication probability model for severe vaginal toxicity based on two dosimetric variables (V70_Gy and D5_%) provides reliable discrimination capability in a cohort of cervical cancer treated with external beam radiation therapy and BT.

DVH Analytics: A DVH database for clinicians and researchers

In this study, we build a vendor-agnostic software application capable of importing and analyzing non-image-based DICOM files for various radiation treatment modalities (i.e., DICOM RT Dose, RT Structure, and RT Plan files). Dose-volume histogram (DVH) and planning data are imported into a SQL database, and methods are provided to manage, edit, view, and download data. Furthermore, the software provides various analytical tools for plan evaluations, plan comparisons, benchmarking, and plan outcome predictions. DVH Analytics is developed using Python, including libraries such as pydicom, dicompyler, psycopg2, SciPy, Statsmodels, and Bokeh for parsing DICOM files, computing DVHs, communicating with a PostgreSQL database, performing statistical analyses, and creating a web-based user interface. This software is open-source and compatible with Windows, Mac OS, and Linux. For proof-of-concept, a database with over 3,000 DVHs from a single physician's head & neck practice was built. From these data, differences in means, correlations, and temporal trends in dose to multiple organs-at-risk (OARs) were observed. Furthermore, an example of the predictive regression tool is reported, where a model was constructed to predict maximum dose to brainstem based on minimum distance from planning target volume (PTV) and treatment beam source-to-skin distance (SSD). With DVH Analytics, we have developed a free, open-source software program to parse, organize, and analyze non-image-based DICOM data for use in a radiation oncology setting. Furthermore, this software can be used to generate statistical models for the purposes of quality control or outcome predictions and correlations.

Predicting patterns of failure in temporal lobe GBMs: possible implications on radiotherapy treatment portals

Background

Characterise patterns of failure of Temporal Lobe (TL) Glioblastoma (GBM) following treatment with relation to normal temporal lobe anatomy and neural pathways.

Methods

335 GBM patients received radiotherapy between 03/2007 and 07/2014, 100 were located in TL. Site of initial tumour and subsequent relapse were subdivided into 5 local TL sites (anterior, lateral, medial, posterior and superior); 5 adjacent regional sites (occipital lobe, inferior frontal lobe, caudate/thalamus/internal/external capsules, fornix/ventricular trigone), and 5 distant failure sites (ventricles, contralateral hemisphere, brainstem, leptomeninges and spine). Extension along major neuroanatomical pathways at initial presentation and at first documented Magnetic Resonance Imaging (MRI) failure were categorised into anterior, superior, medial and posterior pathways.

Results

Of the 100 patients, 86 had radiological progress with a median survival of 17.3 months.

At initial diagnosis, 74% of tumours were linked to one TL site and 94% were confined to the TL. 19% had neural pathway disease at initial pre-treatment MRI. At first recurrence locoregional site failure was 74%. 26% failed within distant sites and 53% patients were noted to have neural pathway involvement.

Initial tumour location predicted for local site recurrence (p < 0.0001), regional site recurrence (p = 0.004) and neural pathway recurrence pattern (p = 0.005), but not for distant sites (p = 0.081).

Conclusion

Most GBMs fail at local or adjacent regional sites. Many of the recurrences occurred in a predictable pattern within a local or regional site, unique to initial TL site with more than half involving neural pathways. Knowledge of tumour infiltration and failure may improve target definition and radiotherapy.

A Comparison of 2D and 3D Kidney Absorbed Dose Measures in Patients Receiving 177Lu-DOTATATE

Objective(s):

To investigate and compare quantitative accuracy of kidney absorbed dose measures made from both 2D and 3D imaging in patients receiving ¹⁷⁷Lu-DOTATATE (Lutate) for treatment of neuroendocrine tumours (NETs).

Methods:

Patients receiving Lutate therapy underwent both whole body planar imaging and SPECT/CT imaging over the kidneys at time points 0.5, 4, 24, and 96-120 hours after injection. Planar data were corrected for attenuation using transmission data, and were converted to units of absolute activity via two methods, using either a calibration standard in the field of view or relative to pre-voiding image total counts. Hand drawn regions of interest were used to generate time activity curves and kidney absorbed dose estimates in OLINDA-EXM. Fully quantitative SPECT data were generated using CT-derived corrections for both scatter and attenuation, before correction for dead time and application of a camera specific sensitivity factor to convert data to units of absolute activity. Volumes of interest were defined for kidney using the co-registered x-ray CT, before time activity curves and absorbed dose measures were generated in OLINDA-EXM, both with and without corrections made to the model for patient specific kidney volumes. Quantitative SPECT data were also used to derive dose maps through dose kernel convolution (DKC), which was treated as the gold standard.

Results:

A total of 50 studies were analysed, corresponding to various cycles of treatment from 21 patients. Planar absorbed dose estimates were consistently higher than SPECT derived estimates by, on average, a factor of 3.

Conclusion:

Quantitative SPECT is considered the gold standard approach for organ specific dosimetry however often relies on in house software. As such planar methods for estimating absorbed dose are much more widely available, and in particular, are often the only source of reference in previously published data. For the case of Lutate dosimetry, planar measures may lead to a three-fold increase in measures of kidney absorbed dose.

Response-adapted radiation therapy for newly diagnosed primary diffuse large B-cell lymphoma of the CNS treated with methotrexate-based systemic therapy

Background

For patients with primary diffuse large B-cell lymphoma of the central nervous system (PCNSL), whole-brain radiation therapy (WBRT) to doses of ≥45 Gy are often given after a partial response (PR) to methotrexate-based induction chemotherapy. We conducted an exploratory analysis to determine whether lower-dose WBRT, given with a boost to sites of persistent disease, might be a reasonable alternative.

Methods and materials

We retrospectively reviewed the records of 22 patients with PCNSL who received WBRT, with or without a boost, after methotrexate-based induction chemotherapy. Outcomes were compared among patients according to response to chemotherapy using the Kaplan-Meier method.

Results

Median follow-up was 52 months. All patients with a complete response (CR) (n = 5) received WBRT to 23.4 Gy. One CR patient died after an in-field relapse. Patients with partial response (PR) (n = 10) received a median whole-brain dose of 23.4 Gy with (n = 8) or without (n = 2) a boost; there were 2 relapses within the central nervous system (CNS). All PR patients were alive at the time of analysis. The overall survival (P = .127) and freedom from relapse within the CNS (P = .967) were not different for patients with CR versus PR. Baseline and follow-up neurocognitive evaluations were available for 4 PR patients, and there were no significant differences between pre- and post-treatment evaluations (P > .05 for language, memory, visual-spatial, attention, or motor functions). All patients who progressed or did not respond to chemotherapy and then received WBRT had died at a median time of 3.4 months. Patients who progressed or did not respond to chemotherapy had worse overall survival (P = .001) and freedom from CNS relapse (P = .005) compared with CR patients.

Conclusions

Among patients with a PR to induction chemotherapy, reduced-dose WBRT with a boost to residual PCNSL may be a viable treatment approach that merits further investigation.

Preclinical optimization of antibody-based radiopharmaceuticals for cancer imaging and radionuclide therapy-Model, vector, and radionuclide selection

Intact antibodies and their truncated counterparts (eg, Fab, scFv fragments) are generally exquisitely specific and selective vectors, enabling recognition of individual cancer-associated molecular phenotypes against a complex and dynamic biomolecular background. Complementary alignment of these advantages with unique properties of radionuclides is a defining paradigm in both radioimmunoimaging and radioimmunotherapy, which remain some of the most adept and promising tools for cancer diagnosis and treatment. This review discusses how translational potency can be maximized through rational selection of antibody-nuclide couples for radioimmunoimaging/therapy in preclinical models.

Validation of previously reported predictors for radiation-induced hypothyroidism in nasopharyngeal cancer patients treated with intensity-modulated radiation therapy, a post hoc analysis from a Phase III randomized trial

This study aimed to validate previously reported dosimetric parameters, including thyroid volume, mean dose, and percentage thyroid volume, receiving at least 40, 45 and 50 Gy (V40, V45 and V50), absolute thyroid volume spared (VS) from 45, 50 and 60 Gy (VS45, VS50 and VS60), and clinical factors affecting the development of radiation-induced hypothyroidism (RHT). A post hoc analysis was performed in 178 euthyroid nasopharyngeal cancer (NPC) patients from a Phase III study comparing sequential versus simultaneous-integrated boost intensity-modulated radiation therapy. RHT was determined by increased thyroid-stimulating hormone (TSH) with or without reduced free thyroxin, regardless of symptoms. The median follow-up time was 42.5 months. The 1-, 2- and 3-year freedom from RHT rates were 78.4%, 56.4% and 43.4%, respectively. The median latency period was 21 months. The thyroid gland received a median mean dose of 53.5 Gy. Female gender, smaller thyroid volume, higher pretreatment TSH level (≥1.55 μU/ml) and VS60 < 10 cm3 were significantly associated with RHT in univariate analyses. Only pretreatment TSH ≥ 1.55 μU/ml and VS60 < 10 cm3 were significant predictors in multivariate analysis. Our results suggested that patients with pretreatment TSH ≥ 1.55 μU/ml should be cautious about the risk of RHT. The VS60 ≥ 10 cm3 is recommended for treatment planning.

Dose constraints in the rectum and bladder following carbon-ion radiotherapy for uterus carcinoma: a retrospective pooled analysis

Background

Carbon-ion radiotherapy (C-ion RT) provides better dose distribution in cancer treatment compared to photons. Additionally, carbon-ion beams provide a higher biological effectiveness, and thus a higher tumor control probability. However, information regarding the dose constraints for organs at risk in C-ion RT is limited. This study aimed to determine the predictive factors for late morbidities in the rectum and bladder after carbon-ion C-ion RT for uterus carcinomas.

Methods

Between June 1995 and January 2010, 134 patients with uterus carcinomas were treated with C-ion RT with curative intent; prescription doses of 52.8–74.4 Gy (relative biological effectiveness) were delivered in 20–24 fractions. Of these patients, 132 who were followed up for > 6 months were analyzed. We separated the data in two subgroups, a 24 fractions group and a 20 fractions group. Late morbidities, proctitis, and cystitis were assessed according to the Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer criteria. The correlations of clinical and dosimetric parameters, V10–V60, D_5cc, D_2cc, and Dmax, with the incidence of ≥grade 1 morbidities were retrospectively analyzed.

Results

In the 24 fractions group, the 3-year actuarial occurrence rates of ≥grade 1 rectal and bladder morbidities were 64 and 9%, respectively. In addition, in the 20 fractions group, the 3-year actuarial occurrence rates of ≥grade 1 rectal and bladder morbidities were 32 and 19%, respectively. Regarding the dose–volume histogram data on the rectum, the D_5cc and D_2cc were significantly higher in patients with ≥grade 1 proctitis than in those without morbidity. In addition, the D_5cc for the bladder was significantly higher in patients with ≥grade 1 cystitis than in those without morbidity. Results of univariate analyses showed that D_2cc of the rectum was correlated with the development of ≥grade 1 late proctitis. Moreover, D_5cc of the bladder was correlated with the development of ≥grade 1 late cystitis.

Conclusions

The present study identified the dose–volume relationships in C-ion RT regarding the occurrence of late morbidities in the rectum and bladder. Assessment of the factors discussed herein would be beneficial in preventing late morbidities after C-ion RT for pelvic malignancies.

Trial registration

Retrospectively registered (NIRS: 16–040).

Electronic supplementary material

The online version of this article (10.1186/s13014-018-1061-7) contains supplementary material, which is available to authorized users.

Pre-clinical experience of an adaptive plan library strategy in radiotherapy of rectal cancer: An inter-observer study

Background and purpose

The clinical target volume (CTV) in radiotherapy of rectal cancer is subject to large deformations. With a plan library strategy, the treatment may be adapted to these deformations. The purpose of this study was to determine feasibility and consistency in plan selection for a plan library strategy in radiotherapy of rectal cancer.

Material and methods

Thirty rectal cancer patients were included in this retrospective study with in total 150 CBCT scans. A library of CTVs was constructed with in-house built software using population statistics on daily rectal deformations. The library consisted of five plans based on: the original CTV, two larger, and two smaller CTVs. An inter-observer study (study-I) was performed to test the consistency in plan choices between four observers (all RTTs). After five months the observers were asked to re-evaluate (study-II) the same set of scans based on refined guidelines.

Results

In study-I the observers reached accordance with the majority choice in 69% of cases. This improved to 87% in study-II. The consensus meeting revealed that inconsistency in choices mainly arose from inadequate instructions, which were later clarified and formulated more accurately.

Conclusion

Plan selection based on daily CBCT scans for rectal cancer patients is feasible, and can be performed consistently by well-trained RTTs.

Reducing the number of CTs performed to monitor personalized dosimetry during peptide receptor radionuclide therapy (PRRT)

Background

Peptide receptor radionuclide therapy (PRRT) with [¹⁷⁷Lu]-DOTA-TATE is an effective treatment of neuroendocrine tumors (NETs). After each cycle of treatment, patient dosimetry evaluates the radiation dose to the risk organs, kidneys, and bone marrow, the most radiosensitive tissues. Absorbed doses are calculated from the radioactivity in the blood and from single photon emission computed tomography (SPECT) images corrected by computed tomography (CT) acquired after each course of treatment. The aim of this work is to assess whether the dosimetry along all treatment cycles can be calculated using a single CT. We hypothesize that the absorbed doses to the risk organs calculated with a single CT will be accurate enough to correctly manage the patients, i.e., whether or not to continue PRRT.

Twenty-four patients diagnosed with metastatic NETs undergoing PRRT with [¹⁷⁷Lu]-DOTA-TATE were retrospectively included in this study. We compared radiation doses to the kidneys and bone marrow using two protocols. In the “classical” one, dosimetry is calculated based on a SPECT and a CT after each treatment cycle. In the new protocol, dosimetry is calculated based on a SPECT study after each cycle but with the first acquired CT for all cycles.

Results

The decision whether or not to stop PRRT because of unsafe absorbed dose to the risk organs would have been the same had the classical or the new protocol been used. The agreement between the cumulative doses to the kidneys and bone marrow obtained from the two protocols was excellent with Pearson’s correlation coefficients r = 0.95 and r = 0.99 (P < 0.0001) and mean relative differences of 5.30 ± 6.20% and 0.48 ± 4.88%, respectively.

Conclusions

Dosimetry calculations for a given patient can be done using a single CT registered to serial SPECTs. This new protocol reduces the need for a hybrid camera in the follow-up of patients receiving [¹⁷⁷Lu]-DOTA-TATE.

Pathological complete response of locally advanced colon cancer after preoperative radiotherapy: a case report and narrative review of the literature

Background

The oncological effectiveness of preoperative radiotherapy for locally advanced colon cancer is unclear. We report a case of pathological complete response in a patient with locally advanced ascending colon cancer after preoperative radiotherapy following failure of chemotherapy.

Case presentation

A 65-year-old Japanese woman presented with malaise and hematochezia. A computed tomography (CT) revealed a tumor in the ascending colon which seemed to infiltrate the adjacent structures. She was diagnosed with locally advanced ascending colon cancer stages T4b, N2a, M0, and IIIC. We selected modified FOLFOX6 with panitumumab as neoadjuvant chemotherapy. However, we discontinued the chemotherapy after the 8th cycle because of disease progression and severe adverse effects. The patient then underwent radiotherapy of 60 Gy in 30 fractions, resulting in significant tumor size reduction. One month after the radiotherapy, we performed a right hemicolectomy with multivisceral resection without complications. Histopathologically, we found no residual cancer cells in the resected specimen. The patient remains alive and has not required additional therapies for 24 months, as there are no signs of recurrence.

Conclusions

The present case suggests that preoperative radiotherapy might be an effective treatment options for locally advanced colon cancer.

A first-in-human study investigating biodistribution, safety and recommended dose of a new radiolabeled MAb targeting FZD10 in metastatic synovial sarcoma patients

Background

Synovial Sarcomas (SS) are rare tumors occurring predominantly in adolescent and young adults with a dismal prognosis in advanced phases. We report a first-in-human phase I of monoclonal antibody (OTSA-101) targeting FZD10, overexpressed in most SS but not present in normal tissues, labelled with radioisotopes and used as a molecular vehicle to specifically deliver radiation to FZD10 expressing SS lesions.

Methods

Patients with progressive advanced SS were included. In the first step of this trial, OTSA-101 in vivo bio-distribution and lesions uptake were evaluated by repeated whole body planar and SPECT-CT scintigraphies from H1 till H144 after IV injection of 187 MBq of ¹¹¹In-OTSA-101. A 2D dosimetry study also evaluated the liver absorbed dose when using ⁹⁰Y-OTSA-101. In the second step, those patients with significant tumor uptake were randomized between 370 MBq (Arm A) and 1110 MBq (Arm B) of ⁹⁰Y-OTSA-101 for radionuclide therapy.

Results

From January 2012 to June 2015, 20 pts. (median age 43 years [21–67]) with advanced SS were enrolled. Even though ¹¹¹In-OTSA-101 liver uptake appeared to be intense, estimated absorbed liver dose was less than 20 Gy for each patient. Tracer intensity was greater than mediastinum in 10 patients consistent with sufficient tumor uptake to proceed to treatment with ⁹⁰Y-OTSA-101: 8 were randomized (Arm A: 3 patients and Arm B: 5 patients) and 2 were not randomized due to worsening PS. The most common Grade ≥ 3 AEs were reversible hematological disorders, which were more frequent in Arm B. No objective response was observed. Best response was stable disease in 3/8 patients lasting up to 21 weeks for 1 patient.

Conclusions

Radioimmunotherapy targeting FZD10 is feasible in SS patients as all patients presented at least one lesion with ¹¹¹In-OTSA-101 uptake. Tumor uptake was heterogeneous but sufficient to select 50% of pts. for ⁹⁰Y-OTSA-101 treatment. The recommended activity for further clinical investigations is 1110 MBq of ⁹⁰Y-OTSA-101. However, because of hematological toxicity, less energetic particle emitter radioisopotes such as Lutetium 177 may be a better option to wider the therapeutic index.

Trial registration

The study was registered on the NCT01469975 website with a registration code NCT01469975 on November the third, 2011.

Temporally feathered intensity-modulated radiation therapy: A planning technique to reduce normal tissue toxicity

PURPOSE

Intensity-modulated radiation therapy (IMRT) has allowed optimization of three-dimensional spatial radiation dose distributions permitting target coverage while reducing normal tissue toxicity. However, radiation-induced normal tissue toxicity is a major contributor to patients' quality of life and often a dose-limiting factor in the definitive treatment of cancer with radiation therapy. We propose the next logical step in the evolution of IMRT using canonical radiobiological principles, optimizing the temporal dimension through which radiation therapy is delivered to further reduce radiation-induced toxicity by increased time for normal tissue recovery. We term this novel treatment planning strategy "temporally feathered radiation therapy" (TFRT).

METHODS

Temporally feathered radiotherapy plans were generated as a composite of five simulated treatment plans each with altered constraints on particular hypothetical organs at risk (OARs) to be delivered sequentially. For each of these TFRT plans, OARs chosen for feathering receive higher doses while the remaining OARs receive lower doses than the standard fractional dose delivered in a conventional fractionated IMRT plan. Each TFRT plan is delivered a specific weekday, which in effect leads to a higher dose once weekly followed by four lower fractional doses to each temporally feathered OAR. We compared normal tissue toxicity between TFRT and conventional fractionated IMRT plans by using a dynamical mathematical model to describe radiation-induced tissue damage and repair over time.

RESULTS

Model-based simulations of TFRT demonstrated potential for reduced normal tissue toxicity compared to conventionally planned IMRT. The sequencing of high and low fractional doses delivered to OARs by TFRT plans suggested increased normal tissue recovery, and hence less overall radiation-induced toxicity, despite higher total doses delivered to OARs compared to conventional fractionated IMRT plans. The magnitude of toxicity reduction by TFRT planning was found to depend on the corresponding standard fractional dose of IMRT and organ-specific recovery rate of sublethal radiation-induced damage.

CONCLUSIONS

TFRT is a novel technique for treatment planning and optimization of therapeutic radiotherapy that considers the nonlinear aspects of normal tissue repair to optimize toxicity profiles. Model-based simulations of TFRT to carefully conceptualized clinical cases have demonstrated potential for radiation-induced toxicity reduction in a previously described dynamical model of normal tissue complication probability (NTCP).

Esophagitis associated with multimodality management of pediatric Ewing sarcoma of thorax

BACKGROUND

Ewing sarcoma of the thoracic spine and chest wall is frequently treated with concurrent chemotherapy and radiation therapy (RT). Treatment-related acute esophagitis can lead to hospitalization and treatment delays. The aim of this study was to analyze the incidence, risk factors, and management of esophagitis in pediatric patients with Ewing sarcoma of the thoracic region.

METHODS

We conducted a single-institution retrospective review of patients treated over a 10-year period. Medical records were reviewed for patient and treatment characteristics associated with Common Terminology Criteria for Adverse Events grade 2 or higher esophagitis. RT plans were also reviewed and various esophageal dose metrics were analyzed.

RESULTS

Twelve of 37 patients (32%) developed acute esophagitis. Neutropenia was associated with an increased risk of esophagitis (60% vs. 14%; P < 0.01). RT significantly contributed to its incidence when maximum esophageal dose was >47 Gy (69% vs. 5%; P < 0.0001) and esophageal D5cm³ was >15 Gy (67% vs. 9%; P < 0.001). All 12 patients with esophagitis were managed with oral opioid analgesics. Nine patients with persistent symptoms received subsequent fluconazole for empiric fungal treatment and each had a decreased need for opioid analgesics within 2-5 days.

CONCLUSION

Approximately one-third of patients with Ewing sarcoma of the thoracic region will develop acute esophagitis. An esophageal D5cm³ dose < 15 Gy and maximal esophageal dose < 47 Gy may keep the rate of acute esophagitis under 5%. However, the association with neutropenia and consistent response to antifungal therapy suggest chemotherapy-associated toxicity and an infectious component as part of the process.

Modeling Patient-Specific Dose-Function Response for Enhanced Characterization of Personalized Functional Damage

PURPOSE

Functional-guided radiation therapy (RT) plans have the potential to limit damage to normal tissue and reduce toxicity. Although functional imaging modalities have continued to improve, a limited understanding of the functional response to radiation and its application to personalized therapy has hindered clinical implementation. The purpose of this study was to retrospectively model the longitudinal, patient-specific dose-function response in non-small cell lung cancer patients treated with RT to better characterize the expected functional damage in future, unknown patients.

METHODS AND MATERIALS

Perfusion single-photon emission computed tomography/computed tomography scans were obtained at baseline (n = 81), midtreatment (n = 74), 3 months post-treatment (n = 51), and 1 year post-treatment (n = 26) and retrospectively analyzed. Patients were treated with conventionally fractionated RT or stereotactic body RT. Normalized perfusion single-photon emission computed tomography voxel intensity was used as a surrogate for local lung function. A patient-specific logistic model was applied to each individual patient's dose-function response to characterize functional reduction at each imaging time point. Patient-specific model parameters were averaged to create a population-level logistic dose-response model.

RESULTS

A significant longitudinal decrease in lung function was observed after RT by analyzing the voxelwise change in normalized perfusion intensity. Generated dose-function response models represent the expected voxelwise reduction in function, and the associated uncertainty, for an unknown patient receiving conventionally fractionated RT or stereotactic body RT. Differential treatment responses based on the functional status of the voxel at baseline suggest that initially higher functioning voxels are damaged at a higher rate than lower functioning voxels.

CONCLUSIONS

This study modeled the patient-specific dose-function response in patients with non-small cell lung cancer during and after radiation treatment. The generated population-level dose-function response models were derived from individual patient assessment and have the potential to inform functional-guided treatment plans regarding the expected functional lung damage. This type of patient-specific modeling approach can be applied broadly to other functional response analyses to better capture intrapatient dependencies and characterize personalized functional damage.

Theranostics of prostate cancer: from molecular imaging to precision molecular radiotherapy targeting the prostate specific membrane antigen

Alterations at the molecular level are a hallmark of cancer. Prostate cancer is associated with the overexpression of prostate-specific membrane antigen (PSMA) in a majority of cases, predominantly in advanced tumors, increasing with the grade or Gleason's score. PSMA can be selectively targeted using radiolabeled PSMA ligands. These small molecules binding the PSMA can be radiolabeled with γ-emitters like ^99mTc and ¹¹¹In or positron emitters like ⁶⁸Ga and ¹⁸F for diagnosis as well as with their theranostic pairs such as ¹⁷⁷Lu (β-emitter) or ²²⁵Ac (α-emitter) for therapy. This review summarizes the theranostic role of PSMA ligands for molecular imaging and targeted molecular radiotherapy, moving towards precision oncology.

Study of dosimetric indices and dose constraints to critical organs for head and neck tumours treated with inverse planned simultaneous integrated boost intensity-modulated radiotherapy

Aim

This study aimed to investigate tolerance dose to organs at risk (OARs) as well as degree of conformity and homogeneity for head and neck cancer patients by using simultaneous integrated boost intensity-modulated radiotherapy technique (SIB IMRT).

Materials and methods

This study analysed 15 head and neck cancer patients receiving treatment using inverse planned SIB IMRT technique. Using a beam energy of 6 MV, two dose levels of 70 and 55·4 Gy were used to treat the tumour. Doses of 2 Gy in 35 fractions and 1·68 Gy in 33 fractions were simultaneously delivered for effective planning target volume (PTV1) and boost planning target volume (PTV2), respectively.

Results

Dose distribution in PTV and critical organs lies within tolerance dose guidelines protecting spinal cord, brain stem, optic chiasm, optic nerve, thus reducing the risk of damage to normal tissues. Minor deviation from tolerance limit was observed for parotid glands. This technique provided highly conformal and homogenous dose distribution as well as better sparing of OARs, hence verifying quality assurance results to be satisfactory.

Findings

SIB IMRT technique offers best solution for preserving organ function by keeping dose below tolerance level. Treatment of head and neck carcinoma using SIB IMRT is feasible, more efficient, and dose escalation is achieved in a single plan.

Precision Oncology and Genomically Guided Radiation Therapy: A Report From the American Society for Radiation Oncology/American Association of Physicists in Medicine/National Cancer Institute Precision Medicine Conference

PURPOSE

To summarize important talking points from a 2016 symposium focusing on real-world challenges to advancing precision medicine in radiation oncology, and to help radiation oncologists navigate the practical challenges of precision, radiation oncology.

METHODS AND MATERIALS

The American Society for Radiation Oncology, American Association of Physicists in Medicine, and National Cancer Institute cosponsored a meeting on precision medicine in radiation oncology. In June 2016 numerous scientists, clinicians, and physicists convened at the National Institutes of Health to discuss challenges and future directions toward personalized radiation therapy. Various breakout sessions were held to discuss particular components and approaches to the implementation of personalized radiation oncology. This article summarizes the genomically guided radiation therapy breakout session.

RESULTS

A summary of existing genomic data enabling personalized radiation therapy, ongoing clinical trials, current challenges, and future directions was collected. The group attempted to provide both a current overview of data that radiation oncologists could use to personalize therapy, along with data that are anticipated in the coming years. It seems apparent from the provided review that a considerable opportunity exists to truly bring genomically guided radiation therapy into clinical reality.

CONCLUSIONS

Genomically guided radiation therapy is a necessity that must be embraced in the coming years. Incorporating these data into treatment recommendations will provide radiation oncologists with a substantial opportunity to improve outcomes for numerous cancer patients. More research focused on this topic is needed to bring genomic signatures into routine standard of care.

Beyond the Knife: The Evolving Nonsurgical Management of Oligometastatic Colorectal Cancer

In patients with liver-limited oligometastatic disease, the goal of treatment can be curative intent. Historically, this was accomplished in patients presenting with upfront resectable disease. The availability of increasingly efficacious chemotherapy and biologic combinations with encouraging response rates led to the potential to convert unresectable disease to resectability. Beyond the backbone of surgery, we now have a portfolio of locoregional strategies to consider.From an interventional radiology perspective, the use of portal vein embolization can facilitate hypertrophy of the liver in anticipation of resection, thus converting unresectable disease to one amenable to a surgical approach with curative intent. Technological advances in liver-directed ablative therapies have afforded the possibility of eliminate radiographically evident disease with the hope for long-term disease control. Advanced radiotherapy techniques are further increasing the therapeutic options for patients with metastatic colorectal cancer. Improvements in external-beam radiotherapy over the past 2 decades include image-guided radiotherapy, intensity-modulated radiotherapy, stereotactic body radiotherapy, and proton-beam therapy. Finally, selective internal radiation therapy (SIRT) with microspheres labeled with the β-emitter ⁹⁰Y enable targeted delivery of radiation to hepatic tumors. A coordinated multidisciplinary approach is required to integrate these nonsurgical adjuncts in an evidence-based manner to optimize outcomes for patients with potentially resectable metastatic disease. In this article, we summarize recent developments in systemic therapy, radiotherapy, and interventional liver-directed therapies that have changed the treatment landscape for patients with oligometastatic colorectal cancer.

Correlation of dose with toxicity and tumour response to 90Y- and 177Lu-PRRT provides the basis for optimization through individualized treatment planning

PURPOSE

Peptide receptor radionuclide therapy (PRRT) with ⁹⁰Y-labelled and ¹⁷⁷Lu-labelled peptides is an effective strategy for the treatment of metastatic/nonresectable neuroendocrine tumours (NETs). Dosimetry provides important information useful for optimizing PRRT with individualized regimens to reduce toxicity and increase tumour responses. However, this strategy is not applied in routine clinical practice, despite the fact that several dosimetric studies have demonstrated significant dose-effect correlations for normal organ toxicity and tumour response that can better guide therapy planning. The present study reviews the key relationships and the radiobiological models available in the literature with the aim of providing evidence that optimization of PRRT is feasible through the implementation of dosimetry.

METHODS

The MEDLINE database was searched combining specific keywords. Original studies published in the English language reporting dose-effect outcomes in patients treated with PRRT were chosen.

RESULTS

Nine of 126 studies were selected from PubMed, and a further five were added manually, reporting on 590 patients. The studies were analysed and are discussed in terms of weak and strong elements of correlations.

CONCLUSION

Several studies provided evidence of clinical benefit from the implementation of dosimetry in PRRT, indicating the potential contribution of this approach to reducing severe toxicity and/or reducing undertreatment that commonly occurs. Prospective trials, possibly multicentre, with larger numbers of patients undergoing quantitative dosimetry and with standardized methodologies should be carried out to definitively provide robust predictive paradigms to establish effective tailored PRRT.

Radiation-Induced Myelitis: Initial and Follow-Up MRI and Clinical Features in Patients at a Single Tertiary Care Institution during 20 Years

Myelitis is a rare complication of radiation exposure to the spinal cord and is often a diagnosis of exclusion. A retrospective review of clinical records and serial imaging was performed to identify subjects with documented myelitis and a history of prior radiation. Eleven patients fulfilled the inclusion criteria. All patients had longitudinally extensive cord involvement with homogeneous precontrast T1 hyperintense signal in the adjacent vertebrae, corresponding to the radiation field. T2 signal abnormalities involving the central two-thirds of the cord were seen in 6/11 patients (55%). The degree of cord expansion and contrast enhancement was variable but was seen in 6 (54%) and 5 (45%) patients, respectively. On follow-up, 2 patients developed cord atrophy, while complete resolution was noted in 1. Clinical improvement was noted in 5 patients, with symptom progression in 2 patients. Our results suggest that radiation myelitis is neither universally progressive nor permanent, and some radiographic and clinical improvement may occur.

Radiation dose constraints for organs at risk in neuro-oncology; the European Particle Therapy Network consensus

PURPOSE

For unbiased comparison of different radiation modalities and techniques, consensus on delineation of radiation sensitive organs at risk (OARs) and on their dose constraints is warranted. Following the publication of a digital, online atlas for OAR delineation in neuro-oncology by the same group, we assessed the brain OAR-dose constraints in a follow-up study.

METHODS

We performed a comprehensive search to identify the current papers on OAR dose constraints for normofractionated photon and particle therapy in PubMed, Ovid Medline, Cochrane Library, Embase and Web of Science. Moreover, the included articles' reference lists were cross-checked for potential studies that met the inclusion criteria. Consensus was reached among 20 radiation oncology experts in the field of neuro-oncology.

RESULTS

For the OARs published in the neuro-oncology literature, we summarized the available literature and recommended dose constraints associated with certain levels of normal tissue complication probability (NTCP) according to the recent ICRU recommendations. For those OARs with lacking or insufficient NTCP data, a proposal for effective and efficient data collection is given.

CONCLUSION

The use of the European Particle Therapy Network-consensus OAR dose constraints summarized in this article is recommended for the model-based approach comparing photon and proton beam irradiation as well as for prospective clinical trials including novel radiation techniques and/or modalities.

Leaflet manual of external beam radiation therapy for hepatocellular carcinoma: a review of the indications, evidences, and clinical trials

The use of external beam radiation therapy (EBRT) in the treatment of hepatocellular carcinoma (HCC), which was rarely performed due to liver toxicity with a previous technique, has increased. Palliation of portal vein thrombosis, supplementation for insufficient transarterial chemoembolization, and provision of new curative opportunities using stereotactic body radiotherapy are the potential indications for use of EBRT. The mechanism of EBRT treatment, with its radiobiological and physical perspectives, differs from those of conventional medical treatment or surgery. Therefore, understanding the effects of EBRT may be unfamiliar to physicians other than radiation oncologists, especially in the field of HCC, where EBRT has recently begun to be applied. The first objective of this review was to concisely explain the indications for use of EBRT for HCC for all physicians treating HCC. Therefore, this review focuses on the therapeutic outcomes rather than the detailed biological and physical background. We also reviewed recent clinical trials that may extend the indications for use of EBRT. Finally, we reviewed the current clinical practice guidelines for the treatment of HCC and discuss the current recommendations and future perspectives.

The clinical features of radiation cataract in patients with ocular adnexal mucosa-associated lymphoid tissue lymphoma

BACKGROUND

To examine the clinical features of radiation cataract in patients with ocular adnexal mucosa-associated lymphoid tissue (MALT) lymphoma.

METHODS

Twenty-one patients with 26 eyes diagnosed with ocular adnexal MALT lymphoma (26 eyes), who were treated in Hokkaido University Hospital, were retrospectively reviewed based on medical records.

RESULTS

Out of the 21 patients, 16 patients (21 eyes) received radiation therapy (RT) with a total dose of 30 Gy. All cases eventually achieved complete remission. Eight of these patients (11 eyes: 52.3%) required cataract surgery after RT. The mean age at surgery was 56.8 (40-70) years. The mean latency between RT and the indication for surgery was 43.3 months. The percentage of females was significantly higher in patients who required surgery (P < 0.01), compared with those without surgery. The eyes of patients who received bolus technique on radiation treatment developed cataract more frequently (P < 0.05). In contrast, none of the patients without RT required cataract surgery.

CONCLUSIONS

Patients with ocular adnexal MALT lymphoma who underwent surgery for radiation cataract were seen more often in relatively young, female patients, and surgery was required about 3 years after RT. A long-term observation may be needed for patients after RT for a tumor. A female sex and the bolus technique may be risk factors for radiation cataract.

Applying Precision Oncology Principles in Radiation Oncology

Radiation therapy is a critical component in the curative management of many solid tumor types, and advances in radiation delivery techniques during the past decade have led to improved disease control and quality of life for patients. During the same period, remarkable advances have also been made in understanding the genomic landscape of tumors; however, treatment decisions in radiation oncology continue to depend primarily on clinical and histopathologic characteristics rather than on the genetic features of the tumor or the patient. With the development of novel genomic techniques and their increasing use in clinical practice, radiation oncology is uniquely positioned to leverage these advances to identify novel biomarkers that could inform radiation dose, field, and the use of concurrent systemic agents. Here, we summarize efforts to use genomic techniques to guide radiation decisions, and we highlight some of the current opportunities and challenges that exist in attempting to apply precision oncology principles in radiation oncology.

Radiotherapeutic implications of the updated ICRP thresholds for tissue reactions related to cataracts and circulatory diseases

Radiation therapy of cancer patients involves a trade-off between a sufficient tumour dose for a high probability of local control and dose to organs at risk that is low enough to lead to a clinically acceptable probability of toxicity. The International Commission on Radiological Protection (ICRP) reviewed epidemiological evidence and provided updated estimates of 'practical' threshold doses for tissue injury, as defined at the level of 1% incidence, in ICRP Publication 118. Particular attention was paid to cataracts and circulatory diseases. ICRP recommended nominal absorbed dose threshold for these outcomes as low as 0.5 Gy. Threshold doses for tissue reactions can be reached in some patients during radiation therapy. Modern treatment planning systems do not account for such low doses accurately, and doses to therapy patients from associated imaging procedures are not generally accounted for. While local control is paramount, the observations of ICRP Publication 118 suggest that radiation therapy plans and processes should be examined with particular care. The research needs are discussed in this paper.

Evaluation of particle radiotherapy for the re-irradiation of recurrent intracranial meningioma

BACKGROUND

With the advance of modern irradiation techniques, the role of radiotherapy (RT) for intracranial meningioma has increased significantly throughout the past years. Despite that tumor's generally favorable outcome with local control rates of up to 90% after ten years, progression after RT does occur. In those cases, re-irradiation is often difficult due to the limited radiation tolerance of the surrounding tissue. The aim of this analysis is to determine the value of particle therapy with its better dose conformity and higher biological efficacy for re-irradiating recurrent intracranial meningioma. It was performed within the framework of the "clinical research group heavy ion therapy" and funded by the German Research Council (DFG, KFO 214).

METHODS

Forty-two patients treated with particle RT (protons (n = 8) or carbon ions (n = 34)) for recurrent intracranial meningioma were included in this analysis. Location of the primary lesion varied, including skull base (n = 31), convexity (n = 5) and falx (n = 6). 74% of the patients were categorized high-risk according to histology with a WHO grading of II (n = 25) or III (n = 6), in the remaining cases histology was either WHO grade I (n = 10) or unknown (n = 1). Median follow-up was 49,7 months.

RESULTS

In all patients, re-irradiation could be performed safely without interruptions due to side effects. No grade IV or V toxicities according to CTCAE v4.0 were observed. Particle RT offered good overall local control rates with 71% progression-free survival (PFS) after 12 months, 56,5% after 24 months and a median PFS of 34,3 months (95% CI 11,7-56,9). Histology had a significant impact on PFS yielding a median PFS of 25,7 months (95% CI 5,8-45,5) for high-risk histology (WHO grades II and III) while median PFS was not reached for low-risk tumors (WHO grade I) (p = 0,03). Median time to local progression was 15,3 months (Q1-Q3 8,08-34,6). Overall survival (OS) after re-irradiation was 89,6% after 12 months and 71,4% after 24 months with a median OS of 61,0 months (95% CI 34,2-87,7). Again, WHO grading had an effect, as median OS for low-risk patients was not reached whereas for high-risk patients it was 45,5 months (95% CI 35,6-55,3).

CONCLUSION

Re-irradiation using particle therapy is an effective method for the treatment of recurrent meningiomas. Interdisciplinary decision making is necessary to guarantee best treatment for every patient.

Esophageal Metal Stents with Concurrent Chemoradiation Therapy for Locally Advanced Esophageal Cancer: Safe or Not?

BACKGROUND

The purpose of this study was to review the risks and benefits of concurrent chemoradiation therapy (CCRT) with esophageal self-expandable metal stents (SEMS) for the treatment of locally advanced esophageal cancer.

MATERIALS AND METHODS

Between January 2014 and December 2016, the data from 46 locally advanced esophageal cancer patients who received CCRT at our institution were retrospectively reviewed. Eight patients who received CCRT concomitant with SEMS placement (SEMS plus CCRT group) and thirty-eight patients who received CCRT without SEMS placement (CCRT group) were identified. The risk of developing esophageal fistula and the overall survival of the two groups were analyzed.

RESULTS

The rate of esophageal fistula formation during or after CCRT was 87.5% in the SEMS plus CCRT group and 2.6% in the CCRT group. The median doses of radiotherapy in the SEMS plus CCRT group and the CCRT group were 47.5 Gy and 50 Gy, respectively. SEMS combined with CCRT was associated with a greater risk of esophageal fistula formation than CCRT alone (hazard ratio [HR], 72.30; 95% confidence interval [CI], 8.62-606.12; p < .001). The median overall survival times in the SEMS plus CCRT and CCRT groups were 6 months and 16 months, respectively. Overall survival was significantly worse in the SEMS plus CCRT group than in the CCRT group (HR, 5.72; 95% CI, 2.15-15.21; p < .001).

CONCLUSION

CCRT concomitant with SEMS for locally advanced esophageal cancer results in earlier life-threatening morbidity and a higher mortality rate than treatment with CCRT alone. Further prospective and randomized studies are warranted to confirm these observations.

IMPLICATIONS FOR PRACTICE

Patients treated with SEMS placement followed by CCRT had higher risk of esophageal fistula formation and inferior overall survival rate compared with patients treated with CCRT alone. SEMS placement should be performed cautiously in patients who are scheduled to receive CCRT with curative intent.

Dosimetric predictors for acute esophagitis during radiation therapy for lung cancer: Results of a large statewide observational study

PURPOSE

The purpose of this study is to identify dosimetric variables that best predict for acute esophagitis in patients treated for locally advanced non-small cell lung cancer in a prospectively accrued statewide consortium.

METHODS AND MATERIALS

Patients receiving definitive radiation therapy for stage II-III non-small cell lung cancer within the Michigan Radiation Oncology Quality Consortium were included in the analysis. Dose-volume histogram data were analyzed to determine absolute volumes (cc) receiving doses from 10 to 60 Gy (V10, V20, V30, V40, V50, and V60), as well as maximum dose to 2 cc (D2cc), mean dose (MD), and generalized equivalent uniform dose (gEUD). Logistic regression models were used to characterize the risk of toxicity as a function of dose and other covariates. The ability of each variable to predict esophagitis, individually or in a multivariate model, was quantified by receiver operating characteristic analysis.

RESULTS

There were 533 patients who met study criteria and were included; 437 (81.9%) developed any grade of esophagitis. Significant variables on univariate analysis for grade ≥2 esophagitis were concurrent chemotherapy, V20, V30, V40, V50, V60, MD, D2cc, and gEUD. For grade ≥3 esophagitis, the predictive variables were: V30, V40, V50, V60, MD, D2cc, and gEUD. In multivariable modeling, gEUD was the most significant predictor of both grade ≥2 and grade ≥3 esophagitis. When gEUD was excluded from the model, D2cc was selected as the most predictive variable for grade ≥3 esophagitis. For an estimated risk of grade ≥3 esophagitis of 5%, the threshold values for gEUD and D2cc were 59.3 Gy and 68 Gy, respectively.

CONCLUSIONS

In this study, we report the novel finding that gEUD and D2cc, rather than MD, were the most predictive dose metrics for severe esophagitis. To limit the estimated risk of grade ≥3 esophagitis to <5%, thresholds of 59.3 Gy and 68 Gy were identified for gEUD and D2cc, respectively.

Early intervention using high-precision radiotherapy preserved visual function for five consecutive patients with optic nerve sheath meningioma

BACKGROUND

There has been a paradigm shift in the treatment for optic nerve sheath meningioma (ONSM) from surgery to fractionated stereotactic radiotherapy (FSRT) in other countries. However, FSRT has seldom been performed in Japan. The purpose of this retrospective study is to reconfirm the effectiveness of early intervention with precision radiotherapy for ONSM reported in our previous study.

METHODS

Five consecutive patients with ONSM were retrospectively analyzed. All patients underwent intensity-modulated radiotherapy (IMRT) or FSRT. They received the early interventions between 1.5 and 7 months after deterioration of the disease. The median dose was 52.8 Gy (range 46.0-59.4 Gy) and the median number of fractions was 25 (range 22-33).

RESULTS

All patients experienced reestablishment of vision at the median follow-up time of 36 months (range 18-54 months). Four of them noted early improvement of visual deficits during the treatment course (range 2-4 weeks) and the remaining patient improved 3 weeks after completion of IMRT. The median tumor reduction was 53% (range 39-75%). One patient with diabetes mellitus developed retinal bleeding as a result of radiation retinopathy 16 months after IMRT, although the doses were acceptable. The remaining 4 patients have no late toxicity at the follow-up time of 31-54 months.

CONCLUSIONS

A paradigm shift is necessary from surgery to early intervention using precision radiotherapy for the treatment of ONSM in Japan.

Dosimetric effects of bolus and lens shielding in treating ocular lymphomas with low-energy electrons

Radiation therapy is an effective treatment for primary orbital lymphomas. Lens shielding with electrons can reduce the risk of high-grade cataracts in patients undergoing treatment for superficial tumors. This work evaluates the dosimetric effects of a suspended eye shield, placement of bolus, and varying electron energies. Film (GafChromic EBT3) dosimetry and relative output factors were measured for 6, 8, and 10 MeV electron energies. A customized 5-cm diameter circle electron orbital cutout was constructed for a 6 × 6-cm applicator with a suspended lens shield (8-mm diameter Cerrobend cylinder, 2.2-cm length). Point doses were measured using a scanning electron diode in a solid water phantom at depths representative of the anterior and posterior lens. Depth dose profiles were compared for 0-mm, 3-mm, and 5-mm bolus thicknesses. At 5 mm (the approximate distance of the anterior lens from the surface of the cornea), the percent depth dose under the suspended lens shield was reduced to 15%, 15%, and 14% for electron energies 6, 8, and 10 MeV, respectively. Applying bolus reduced the benefit of lens shielding by increasing the estimated doses under the block to 27% for 3-mm and 44% for 5-mm bolus for a 6 MeV incident electron beam. This effect is minimized with 8 MeV electron beams where the corresponding values were 15.5% and 18% for 3-mm and 5-mm bolus. Introduction of a 7-mm hole in 5-mm bolus to stabilize eye motion during treatment altered lens doses by about 1%. Careful selection of electron energy and consideration of bolus effects are needed to account for electron scatter under a lens shield.

Liver reirradiation for patients with hepatocellular carcinoma and liver metastasis

PURPOSE

This study aimed to assess the safety and efficacy of administering liver reirradiation to patients with primary liver tumors or liver metastasis.

METHODS AND MATERIALS

A total of 49 patients (with 64 individual tumors) who received liver reirradiation at our institution between June 2008 and December 2016 were identified for retrospective review. Patients were treated to the same, different, or a combination of previously treated liver tumors for recurrent primary (53%) or metastatic (47%) disease using photons or protons. Clinical and treatment-related factors were compiled and patients were monitored for toxicity and evidence of classic or nonclassic radiation-induced liver disease. Survival was estimated with the Kaplan-Meier method and cumulative incidence of local failure (LF) was used to estimate LF using the Response Evaluation Criteria in Solid Tumors version 1.1.

RESULTS

The median age at the time of reirradiation was 72 years and the median interval between radiation courses was 9 months. At a median follow-up of 10.5 months, 36 patients (73%) had died, 9 patients (18%) were alive, and 4 patients (8%) were lost to follow-up. The median survival for the cohort was 14 months. The overall 1-year estimate of LF was 46.4%. The 1-year estimates of LF for liver metastases and hepatocellular carcinoma were 61.0% and 32.5%, respectively. The average prescription dose was similar between the reirradiation and initial courses (equivalent dose in 2 Gy fractions EQD2: 65.0 vs 64.3 Gy_{α/β = 10}, respectively) but the average dose to the untreated liver was lower at the time of reirradiation (EQD2: 10.5 vs 13.9 Gy_{α/β = 3}, respectively, P = .01). Among patients with hepatocellular carcinoma, the average normal liver dose was significantly larger for patients who exhibited a worsening of Child-Pugh score after reirradiation compared with those who did not (1210 cGy vs 759 cGy, P = .04). With regard to toxicity, 85.7% of patients experienced grade 1 to 2 toxicity, 4.1% developed grade 3, and only 2 patients (4.1%) met the criteria for radiation-induced liver disease after reirradiation.

CONCLUSIONS

Liver reirradiation may be an effective and safe option for select patients; however, further prospective study is necessary to establish treatment guidelines and recommended dosing.

Radiotherapy of Liver Malignancies. From Whole Liver Irradiation to Stereotactic Hypofractionated Radiotherapy

Aims and background

Until recently radiotherapy of hepatic malignancies has played a limited role due to the well-known limited radiotolerance of the liver. The aim of this paper is to review the available data on the risk of radiation-induced liver disease (RILD) and to define the modern role of radiotherapy in the management of patients with metastatic or primary liver malignancies.

Methods

The advent of three-dimensional conformal treatment planning with dose-volume histogram analysis has made the study of partial liver irradiation possible. Limited portions of the liver may withstand high doses of radiation with minimal risk of RILD. Patients with solitary unresectable liver tumors may be treated with high-dose radiotherapy with curative intent. Recently, the feasibility of stereotactically guided treatment techniques with a single fraction or few treatment sessions has been explored in numerous institutions.

Results

The radiation tolerance of the whole liver found by several investigations is in the order of approximately 30 Gy, which seriously restricts its clinical application. The role of whole liver irradiation therefore appears of limited benefit in the palliation of patients with multiple liver metastases. The use of three-dimensional conformal techniques has made partial liver irradiation possible to doses in the 70–80 Gy range with conventional fractionation. At least two published series have reported improved local control and survival rates with dose escalation with three-dimensional conformal radiotherapy in patients with unresectable liver metastases. Similar outcomes have been recently reported with single dose (or hypofractionated) stereotactic radiotherapy both in metastatic and primary hepatic malignancies with minimal morbidity. Accurate target delineation and treatment reproducibility are the key to the success of this novel treatment approach, and specific treatment planning techniques and patient setup procedures must be developed to implement it.

Conclusions

Stereotactic high-dose radiotherapy is technically feasible for the treatment of inoperable liver malignancies, with the potential of high local control and low morbidity. Definitive evidence on the clinical advantages of this technique over other more established treatments can only be gathered from well-designed clinical studies.

Feasibility of Intensity-Modulated Radiation Therapy in the Treatment of Advanced Cervical Chordoma

Aims and Background

Postoperative radiation is often given in cases of cervical chordoma because of the high incidence of local recurrence. The tumor mass usually surrounds the spinal cord and infiltrates vertebral bone. A combined technique using protons or electrons to boost the initial photon fields is generally applied. We evaluated the use of dynamic intensity-modulated radiation therapy as an alternative technique for treating advanced cervical chordoma.

Methods and Study Design

A female patient with incomplete resection of a vertebral chordoma surrounding C2-C3 was irradiated with a total dose of 58 Gy (ICRU point) in 2 Gy daily fractions for 29 days between December 2001 and January 2002. Beam arrangement consisted of seven 6 MV non-opposed coplanar fields. Pretreatment quality assurance included checking of the absolute dose at reference points and 2D dose map analysis. Treatment was delivered with a 120-leaf collimator in sliding window mode. To verify the daily setup, portal images at 0° and 90° were compared with the simulation images before treatment delivery (manual matching) and after treatment delivery (automatic anatomy matching).

Results and Conclusions

The mean dose to the planning target volume (PTV) was 57.6 ± 2.1 Gy covering 95% of the PTV per 95% isodose. The minimum dose to the PTV (D99) was 53.6 Gy in the overlapping area between the PTV and the spinal cord planning organ at risk volume (PRV). The maximum dose to the spinal cord was 42.2 Gy and to the spinal cord PRV (8 mm margin) 53.7 Gy. The mean dose to the parotid glands was 37.4 Gy (homolateral gland) and 19.5 Gy (contralateral gland). Average deviation in setup was -1.1 ± 2.5 mm (anterior-posterior), 2.4 ±1.3 mm (latero-lateral), 0.7 ± 0.9 mm (craniocaudal) and -0.43 ± 1° (rotation).

Conclusions

In the treatment of chordomas surrounding the spinal cord, intensity-modulated radiotherapy can provide high dose homogeneity and PTV coverage. Frequent digital portal image-based setup control is able to reduce random positioning errors for head and neck cancer patients immobilized with conventional thermoplastic masks.

Innovations in Three-Dimensional Treatment Planning and Quality Assurance

Radiation therapy treatment planning and treatment delivery are in the process of changing dramatically over the next several years. This change has been driven in large part by continued advances in computer hardware and software and in medical imaging. Three-dimensional radiation treatment planning systems are rapidly being implemented in clinics around the world. These developments in turn have prompted manufacturers to employ advanced microcircuitry and computer technology to produce treatment delivery systems capable of precise shaping of dose distributions via computer-controlled multileaf collimators which cause the beam intensity to be varied across the beam. Image-based 3D planning and beam intensity modulated delivery systems show significant potential for improving the quality of radiotherapy and improving the efficiency with which radiation therapy can be planned and delivered. However, significant research and development work on these systems and their clinical use remains to be performed. The techniques used for the treatment planning and the methods used for quality assurance procedures and testing must all be revised and/or redesigned to allow efficient clinical use of these technological advances. Although much of the current 3D radiation therapy process requires interactive tasks (and some still very laborious) the path is clear toward solving the technological obstacles so that a nearly automated planning, delivery, and verification system will become a reality over the next decade. Such systems will allow radiation oncologists to significantly increase dose to many tumor sites while concomitantly lowering doses to critical organs-at-risk. Most of the tasks will be automated, thus lowering the overall costs currently needed to provide high-quality external beam radiation therapy.

Prognostic factors of radiation dermatitis following passive-scattering proton therapy for breast cancer

BACKGROUND

To identify prognostic factors for grade 3 radiation dermatitis following passive-scattering proton therapy for breast cancer.

METHODS

This retrospective study included data on 23 (11 post-mastectomy and 12 post-lumpectomy) breast cancer patients who underwent proton therapy with the passive scattering technique in our institute from 2012 to 2016. Each patient received 50-50.4 cobalt Gy equivalent (CGE) at 1.8 or 2 CGE per daily fraction. Logistic regression analysis was performed to identify prognostic factors for grade 3 skin toxicity. Receiver operating characteristic (ROC) curve analysis and the area under the curve (AUC) were used to evaluate the performance of the models.

RESULTS

43% of the studied patients developed grade 3 radiation dermatitis. The dose-volume histogram (DVH) parameters of V52.5CGE and D10cm³ to skin5mm were correlated with grade 3 radiation dermatitis in both univariate and multivariate logistic regression analyses. Univariate logistic regression analysis suggested that D10cm³ to skin5mm (AUC = 0.69) and V52.5CGE to skin5mm (AUC = 0.70) were prognostic for grade 3 skin toxicity. The models using the combination of D10cm³ to skin5mm or V52.5CGE to skin5mm with breast volume marginally increased the AUC to 0.72 and 0.73, respectively. Models using the combination of D10cm³ to skin5mm or V52.5CGE to skin5mm with history of smoking increased the AUC to 0.75 and 0.83, respectively.

CONCLUSION

In the current study, we identified prognostic factors for grade 3 radiation dermatitis in patients treated with passive-scattering proton therapy for breast cancer. This study provides promising tool for identifying high risk patients for whom treatment plan adjustment could be done to reduce the risk of radiation-induced grade 3 skin toxicity.

Kidney-Sparing Radiotherapy by Multiple-Field Three-Dimensional Technique in the Postoperative Management of Patients with Gastric Cancer: Comparison with Standard Two-Field Conformal Technique

AIMS AND BACKGROUND

The opposed two-field technique is the standard approach for delivering adjuvant radiotherapy to patients with resected gastric cancer. Since a considerable radiation dose may reach both kidneys with this beam arrangement, with a potential risk of late effects, we investigated whether the CT-based multiple-field (M-F) approach was superior in terms of sparing critical organs at risk.

METHODS

From March 2001 to March 2004, 19 patients with radically resected gastric cancer entered the study. They were treated with adjuvant chemoradiotherapy according to the INT 0116 protocol. For each patient dose-volume histograms were calculated and the volume values of both kidneys and liver receiving 25 Gy (V25), 30 Gy (V30) and 40 Gy (V40) individually estimated with the M-F and two-field techniques were compared in detail.

RESULTS

Right kidney median V25, V30 and V40 values for the two-field and M-F techniques were 1.50%, 0%, 0% and 0%, 0% and 0%, respectively (P < 0.005, P < 0.01, P < 0.05). Left kidney median V25, V30 and V40 values for the M-F and two-field technique were 16%, 9.80%, 0.90% and 33.20%, 30.20%, 21.40% (P < 0.001, P < 0.0005, P < 0.0005). Liver median V25, V30 and V40 values for the M-F and two-field techniques were 51.30%, 22.30%, 8.90% and 13.30%, 11.60%, 8.10%, respectively (P < 0.0001, P < 0.0005 and P = 0.18).

CONCLUSIONS

Our comparison revealed that with the multiple-field technique the right kidney may be largely spared from irradiation; with respect to the two-field technique, the left kidney may receive a significantly reduced dose; however, the liver receives an increased dose that warrants careful long-term monitoring of hepatic function.

Salivary flow rate after conventional and intensity-modulated radiation therapy

BACKGROUND

Conventional 3-dimensional conformal radiation therapy (3DCRT) for head and neck cancer (HNC) can cause hyposalivation, leading to caries and tooth extraction-related osteoradionecrosis. Intensity-modulated radiation therapy (IMRT) delivers more focused radiation than does 3DCRT. To reduce hyposalivation, the Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) guidelines limit salivary gland radiation dose. In this study, the authors compared the salivary flow rate in patients receiving 3DCRT and those receiving IMRT and evaluated the effect of their treatment satisfying the QUANTEC guidelines on hyposalivation.

METHODS

The authors evaluated findings in 96 patients with HNC who received radiation therapy (RT); 20 received unilateral 3DCRT, 17 received bilateral 3DCRT, and 59 received IMRT. The authors measured stimulated whole saliva before radiation and 3 and 12 months after radiation. The authors defined hyposalivation as stimulated whole saliva less than 3.5 grams per 5 minutes.

RESULTS

At 12 months, 50% and 54% of patients receiving unilateral 3DCRT and IMRT, respectively, exhibited nonstatistically significant hyposalivation compared with 71% of patients receiving bilateral 3DCRT (P = .2). A lower proportion of patients receiving IMRT (27%) and unilateral 3DCRT (5%) had decreased salivary flow (< 25% of baseline) than did those receiving bilateral 3DCRT (59%; P < .004); fewer patients whose treatment satisfied the QUANTEC guidelines exhibited hyposalivation than patients whose treatment did not fullfill QUANTEC guidelines (39% versus 71%; P < .002).

CONCLUSIONS

Twelve months after RT for HNC, treatment satisfying the QUANTEC guidelines resulted in decreased hyposalivation. Unilateral 3DCRT and IMRT may result in less hyposalivation than does bilateral 3DCRT.

PRACTICAL IMPLICATIONS

Patients with HNC treated with modern RT techniques have a lower risk of developing hyposalivation, particularly if the QUANTEC guidelines are met, which also may result in decreased dental caries, tooth extractions, and postextraction osteoradionecrosis. Management of HNC requires a multidisciplinary team, including dentists and radiation oncologists.

Dosimetric and Radiobiological Evaluation of Patient Setup Accuracy in Head-and-neck Radiotherapy Using Daily Computed Tomography-on-rails-based Corrections

Introduction:

This study evaluates treatment plans aiming at determining the expected impact of daily patient setup corrections on the delivered dose distribution and plan parameters in head-and-neck radiotherapy.

Materials and Methods:

In this study, 10 head-and-neck cancer patients are evaluated. For the evaluation of daily changes of the patient internal anatomy, image-guided radiation therapy based on computed tomography (CT)-on-rails was used. The daily-acquired CT-on-rails images were deformedly registered to the CT scan that was used during treatment planning. Two approaches were used during data analysis (“cascade” and “one-to-all”). The dosimetric and radiobiological differences of the dose distributions with and without patient setup correction were calculated. The evaluation is performed using dose–volume histograms; the biologically effective uniform dose () and the complication-free tumor control probability (P₊) were also calculated. The dose–response curves of each target and organ at risk (OAR), as well as the corresponding P₊ curves, were calculated.

Results:

The average difference for the “one-to-all” case is 0.6 ± 1.8 Gy and for the “cascade” case is 0.5 ± 1.8 Gy. The value of P₊ was lowest for the cascade case (in 80% of the patients).

Discussion:

Overall, the lowest P_I is observed in the one-to-all cases. Dosimetrically, CT-on-rails data are not worse or better than the planned data.

Conclusions:

The differences between the evaluated “one-to-all” and “cascade” dose distributions were small. Although the differences of those doses against the “planned” dose distributions were small for the majority of the patients, they were large for given patients at risk and OAR.

Dosimetric Comparison of Treatment Plans Using Physical Wedge and Enhanced Dynamic Wedge for the Planning of Breast Radiotherapy

The aim of this study is to compare the physical wedge (PW) with enhanced dynamic wedge (EDW) to determine the difference in the dose distribution affecting the treated breast and the contralateral breast, lungs, heart, esophagus, spine, and surrounding skin in the radiotherapy of breast cancer. Computed tomography (CT) data sets of 30 breast cancer patients were selected from the database for the study. The treatment plans which were executed with PW were re-planned with EDW without changing the beam parameters. Keeping the wedge angles same, the analytic anisotropic algorithm (AAA) with heterogeneity correction was used for dose calculation in all plans. The prescription was 50 Gy in 25 fractions. The dose- volume histogram (DVH) of the planning target volume (PTV) and critical structures of both PW and EDW plans were analyzed. The analysis showed that the maximum dose within the target volume is higher in EDW plan compared to PW plan. However the PTV conformity index (CI) remained the same in both plans. For all the critical structures, the EDW technique offered less dose compared to PW technique. The effect of volume of the contralateral breast on the dose to contralateral breast and the effect of volume of PTV breast for patients with carcinoma left breast on the dose to heart were studied and analyzed for the two wedges. No correlation between volumes and dose parameters was found for the two techniques. The number of monitor units to deliver a particular dose with EDW field is less than that of PW field due to change in wedge factor. As EDW produces less scattered dose to structures outside the treatment field, the risk of a second malignancy can be reduced with this technique.

Concomitant 177Lu-DOTATATE and Capecitabine Therapy in Patients With Advanced Neuroendocrine Tumors: A Long-term-Outcome, Toxicity, Survival, and Quality-of-Life Study

PURPOSE

The purpose of this study was to evaluate the outcome, toxicity, survival, and quality of life in patients with advanced neuroendocrine tumors.

METHODS

One hundred sixty-seven patients were enrolled in the study. All patients underwent baseline Ga-DOTANOC PET/CT scans. Lu-DOTATATE therapy was administered quarterly along with oral capecitabine therapy in group 1 patients (n = 88), whereas group 2 patients (n = 79) were treated only with Lu-DOTATATE. Hematologic, kidney function, liver function tests and chromogranin A levels were recorded before and after therapy at 2-week, 4-week, and 3-month intervals. Biochemical and morphological responses were assessed with the trend in chromogranin A levels and Response Evaluation Criteria in Solid Tumors 1.1 criteria, respectively.

RESULTS

There was no significant difference in the hemoglobin levels after Lu-DOTATATE therapy (P = 0.4892). In most patients, there was a decrease in the platelet levels; however, all the patients had platelet counts greater than 100,000/μL with no platelet toxicity. There was no toxicity related to leukocytes. Two patients showed renal insufficiencies. No hepatotoxicity was observed in any of the patients. According to Response Evaluation Criteria in Solid Tumors 1.1 criteria, in group 1 patients, the response was partial response in 34% of the patients, stable disease in 50.2%, and progressive disease in 6.8% versus partial response in 6.3%, stable disease in 60.9%, and progressive disease in 26.5% among group 2 patients. The median overall survival (OS) and progression-free survival (PFS) was not reached in group 1 patients. The median OS and PFS in group 2 patients were 48 months. Ki-67 tumor proliferation index was significantly associated with increased risk of disease progression.

CONCLUSIONS

Addition of capecitabine therapy with Lu-DOTATATE therapy lengthens the OS and PFS. Patients with aggressive disease may benefit from this synergetic therapeutic approach.

Dosimetrical and radiobiological approach to manage the dosimetric shift in the transition of dose calculation algorithm in radiation oncology: how to improve high quality treatment and avoid unexpected outcomes?

BACKGROUND

For a given prescribed dose of radiotherapy, with the successive generations of dose calculation algorithms, more monitor units (MUs) are generally needed. This is due to the implementation of successive improvements in dose calculation: better heterogeneity correction and more accurate estimation of secondary electron transport contribution. More recently, there is the possibility to report the dose-to-medium, physically more accurate compared to the dose-to-water as the reference one. This last point is a recent concern and the main focus of this study.

METHODS

In this paper, we propose steps for a general analysis procedure to estimate the dosimetric alterations, and the potential clinical changes, between a reference algorithm and a new one. This includes dosimetric parameters, gamma index, radiobiology indices based on equivalent uniform dose concept and statistics with bootstrap simulation. Finally, we provide a general recommendation on the clinical use of new algorithms regarding the dose prescription or dose limits to the organs at risks.

RESULTS

The dosimetrical and radiobiological data showed a significant effect, which might exceed 5-10%, of the calculation method on the dose the distribution and clinical outcomes for lung cancer patients. Wilcoxon signed rank paired comparisons indicated that the delivered dose in MUs was significantly increased (> 2%) using more advanced dose calculation methods as compared to the reference one.

CONCLUSION

This paper illustrates and explains the use of dosimetrical, radiobiologcal and statistical tests for dosimetric comparisons in radiotherapy. The change of dose calculation algorithm may induce a dosimetric shift, which has to be evaluated by the physicists and the oncologists. This includes the impact on tumor control and on the risk of toxicity based on normal tissue dose constraints. In fact, the alteration in dose distribution makes it hard to keep exactly the same tumor control probability along with the same normal tissue complication probability.

Assessment of Organ Dosimetry for Planning Repeat Treatments of High-Dose 131I-MIBG Therapy: 123I-MIBG Versus Posttherapy 131I-MIBG Imaging

PURPOSE

To evaluate detailed organ-based radiation-absorbed dose for planning double high-dose treatment with I-MIBG.

METHODS

In a prospective study, 33 patients with high-risk refractory or recurrent neuroblastoma were treated with high-dose I-MIBG. Organ dosimetry was estimated from the first I-MIBG posttherapy imaging and from subsequent I-MIBG imaging prior to the planned second administration. Three serial whole-body scans were performed per patient 2 to 6 days after I-MIBG therapy (666 MBq/kg or 18 mCi/kg) and approximately 0.5, 24, and 48 hours after the diagnostic I-MIBG dose (370 MBq/kg or 10 mCi/1.73 m). Organ radiation doses were calculated using OLINDA. I-MIBG scan dosimetry estimations were used to predict doses for the second I-MIBG therapy and compared with I-MIBG posttherapy estimates.

RESULTS

Mean ± SD whole-body doses from I-MIBG and I-MIBG scans were 0.162 ± 112 and 0.141 ± 0.068 mGy/MBq, respectively. I-MIBG and I-MIBG organ doses were variable-generally higher for I-MIBG-projected doses than those projected using posttherapy I-MIBG scans. Mean ± SD doses to liver, heart wall, and lungs were 0.487 ± 0.28, 0.225 ± 0.20, and 0.40 ± 0.26, respectively, for I-MIBG and 0.885 ± 0.56, 0.618 ± 0.37, and 0.458 ± 0.56, respectively, for I-MIBG. Mean ratio of I-MIBG to I-MIBG estimated radiation dose was 1.81 ± 1.95 for the liver, 2.75 ± 1.84 for the heart, and 1.13 ± 0.93 for the lungs. No unexpected toxicities were noted based on I-MIBG-projected doses and cumulative dose limits of 30, 20, and 15 Gy to liver, kidneys, and lungs, respectively.

CONCLUSIONS

For repeat I-MIBG treatment planning, both I-MIBG and I-MIBG imaging yielded variable organ doses. However, I-MIBG-based dosimetry yielded a more conservative estimate of maximum allowable activity and would be suitable for planning and limiting organ toxicity with repeat high-dose therapies.

Kidney dosimetry during 177Lu-DOTATATE therapy in patients with neuroendocrine tumors: aspects on calculation and tolerance

BACKGROUND

Fractionated therapy with ¹⁷⁷Lu-DOTATATE has been reported to be an effective treatment for patients with metastasized neuroendocrine tumors. To optimize the treatment, absorbed doses to risk organs are calculated for the individual patient. For each organ, absorbed dose due to activity in the organ itself (self-dose) and that originating from other organs (cross-dose) are calculated from serial measurements to obtain the activity distribution following treatment. The main aim of the present work were to calculate the cross-dose contribution to the total absorbed kidney dose.

METHODS

Five hundred patients with neuroendocrine tumors undergoing therapy with ¹⁷⁷Lu-DOTATATE were included. Scintigraphic planar whole body images and single photon emission computed tomography/computed tomography (SPECT/CT) over the abdomen were acquired at 1, 4 and 7 days after treatment. Kidney self-dose was calculated based on radioactivity distribution obtained from SPECT/CT. Cross-dose to kidneys was estimated using organ-based analysis of planar whole body images and cross-fire dose factors from Olinda/EXM 1.1.

RESULTS

Cross-dose to kidneys in the majority of patients were less than 2% and almost all cross-doses were less than 10%. Cross-dose exceeded 10% only in rare cases of patients with high tumor burden and low absorbed doses to kidneys.

CONCLUSIONS

The absorbed dose from ¹⁷⁷Lu-octreotate to solid organs due to cross-fire is generally low and can usually be neglected.

Clinical impact of boost irradiation to pelvic lymph node in uterine cervical cancer treated with definitive chemoradiotherapy

The aim of this study was to analyze tumor control and clinical outcomes of patients with uterine cervical cancer treated by chemoradiotherapy according to pelvic lymph node (PLN) positivity and boost irradiation to PLN and to determine toxicities associated with boost irradiation.We retrospectively reviewed patients with uterine cervical cancer treated with chemoradiotherapy between March 2000 and April 2015. Clinical characteristics, failure pattern, and survival outcomes of patients with or without PLN metastasis and those with or without boost irradiation were analyzed.A total of 80 cases were PLN-negative and 46 were PLN-positive. A total of 11 patients underwent PLN boost irradiation. The 2-year and 5-year overall survival (OS) rates showed significant difference between the PLN-positive and PLN-negative groups (P = .010). The 2-year and 5-year progression-free survival (PFS) rates showed significant difference between the 2 groups (P = .032). The 2-year and 5-year OS rates of the no-boost irradiation group were 82.9% and 58.3%, respectively, whereas all patients in the boost irradiation group were alive at the time of analysis (P = .065). There was no recurrence in the boost irradiation group. The difference in PFS was significant between the boost and the no-boost irradiation groups (P = .023). The 2-year and 5-year pelvic-recurrence free survival (PRFS) did not show significant difference but the tendency of increased risk of pelvic recurrence in no-boost group (boost vs no-boost; 81.9% and 70.2% vs 100% and 100% in 2-year and 5-year PRFS, respectively, P = .156). Boost irradiation to PLN could improve locoregional control especially in large pelvic LN (≥1.5 cm). Our results showed that only 1 acute and late toxicity of higher than grade 3 occurred.PLN metastasis was significant prognostic factor in cervix cancer treated by chemoradiotherapy. In the boost irradiation group, there was no recurrence or death with significantly better PFS. Boost irradiation to PLN is expected to improve locoregional control, but further follow-up and assessment are needed.

Hybrid Tri-Co-60 MRI radiotherapy for locally advanced rectal cancer: An in silico evaluation

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Tri-Co-60 MRI radiotherapy (RT) is feasible in locally advanced rectal cancer.

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Larger volumes of normal tissue receive low-moderate doses in Tri-Co-60 MRI RT.

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Further studies on functional imaging applications and LinacMRI approach are needed.

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Tri-Co-60 MRI might represent a safe irradiation technique for pelvic tumors.

Introduction

Aim of this paper is to investigate the plan quality of a tri-Co-60 MRI-Hybrid system for intensity-modulated radiation therapy (IMRT) in patients affected by locally advanced rectal cancer (LARC) undergoing neo-adjuvant radiotherapy.

Materials and methods

Ten consecutive LARC patients were selected. Tri-Co-60 step and shoot IMRT plans were generated simulating the presence of the magnetic field (B_on) or not (B_off) with the dedicated treatment planning system (TPS).

The total planned dose was 45 Gy in 25 fractions to the mesorectum and the pelvic nodes (planning target volume 2, PTV2) and 55 Gy to the tumor and correspondent mesorectum (PTV1) through simultaneous integrated boost (SIB). Tri-Co-60 IMRT plans were compared with Volumetric Modulated Arc Therapy (VMAT) and IMRT plans for Linear Accelerator (Linac).

Results

B_on and B_off tri-Co-60 IMRT plans showed no relevant differences. Mean values of PTV1 and PTV2 receiving at least 95% of the D_p (V_95%) were higher than 95% in all treatment plans. All plans met the V_105% constraint for the PTV1. Mean values of V_105% for the PTV2 were 14.8, 5.0, and 7.3% respectively for tri-Co-60, VMAT and IMRT. Mean Wu’s HI values were similar in all plans (7.4–7.8%). All plans met the V_45Gy constraint for small bowel, but mean V_45Gy value was higher with tri-Co-60.

Bladder irradiation was comparable and always lower than the chosen D max 65 Gy constraint.

Mean values of V_5Gy and V_20Gy to the body and median skin doses were higher with tri-Co-60 plans.

Discussion

Treatment plans with Tri-Co-60 step and shoot IMRT met the dose-volume objectives in patients with LARC. Nevertheless, a larger volume of normal tissue received low-moderate doses when compared with Linac based VMAT and IMRT.

Late cutaneous effects of a local potent steroid during adjuvant radiotherapy for breast cancer

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Development of late skin reactions are less common with steroid treatment during ERT.

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Combination of a local corticosteroid and radiotherapy did not result in atrophy.

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Adjuvant corticosteroid treatment did not increase in late skin toxicity.

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Seven of the twenty-one patients who underwent mastectomy developed telangiectasia.

Purpose

The aim of this study was to evaluate whether treatment with a local potent corticosteroid during adjuvant external radiotherapy (ERT) of breast cancer is associated with late skin toxicity.

Material and methods

Sixty patients (32 treated with potent corticoid cream versus 28 controls treated with moisturizer) who had been included in a randomized study on prophylactic local corticosteroid treatment under adjuvant ERT in 2009 and 2010 were subjected to a follow-up study in 2016.

Assessments of skin texture were registered according to the Late Radiation Morbidity Scoring Scheme (RTOG). Dryness, skin colour and skin thickness were objectively measured using non-invasive instruments. The patients were assessed for differences between their treated and untreated breasts.

Results

Skin atrophy was not noticed in any of the 60 patients. Objective instrumental measurements did not reveal any significant differences in skin dryness, colour, pigmentation or skin thickness over the average follow-up time of six years. Clinical assessment based on the RTOG scoring system revealed that the odds ratio of having late skin problems in patients treated with moisturizer compared to patients treated with corticosteroid was 3.2 (95% CI: 1.0–10.1).

Patients reported minor cosmetic dermatological sequelae. Seven patients developed telangiectasia, which caused cosmetic inconvenience.

Conclusion

In this study, prophylactic corticosteroid treatment to ameliorate radiation dermatitis during adjuvant ERT of breast cancer was not associated with an increase in late skin toxicity nor did it result in skin atrophy. This study is limited by its small sample size, and the risk for false positive findings.

Clinical outcome after particle therapy for meningiomas of the skull base: toxicity and local control in patients treated with active rasterscanning

BACKGROUND

Meningiomas of the skull base account for 25-30% of all meningiomas. Due to the complex structure of the cranial base and its close proximity to critical structures, surgery is often associated with substantial morbidity. Treatment options include observation, aggressive surgical intervention, stereotactic or conventional radiotherapy. In this analysis we evaluate the outcome of 110 patients with meningiomas of the skull base treated with particle therapy. It was performed within the framework of the "clinical research group heavy ion therapy" and supported by the German Research Council (DFG, KFO 214).

METHODS

Between May 2010 and November 2014, 110 Patients with skull base meningioma were treated with particle radiotherapy at the Heidelberg Ion Therapy Center (HIT). Primary localizations included the sphenoid wing (n = 42), petroclival region (n = 23), cavernous sinus (n = 4), sella (n = 10) and olfactory nerve (n = 4). Sixty meningiomas were benign (WHO °I); whereas 8 were high-risk (WHO °II (n = 7) and °III (n = 1)). In 42 cases histology was not examined, since no surgery was performed. Proton (n = 104) or carbon ion (n = 6) radiotherapy was applied at Heidelberg Ion Therapy Center (HIT) using raster-scanning technique for active beam delivery. Fifty one patients (46.4%) received radiotherapy due to tumor progression, 17 (15.5%) after surgical resection and 42 (38.2%) as primary treatment.

RESULTS

Median follow-up in this analysis was 46,8 months (95% CI 39,9-53,7; Q1-Q3 34,3-61,7). Particle radiotherapy could be performed safely without toxicity-related interruptions. No grade IV or V toxicities according to CTCAE v4.0 were observed. Particle RT offered excellent overall local control rates with 100% progression-free survival (PFS) after 36 months and 96.6% after 60 months. Median PFS was not reached due to the small number of events. Histology significantly impacted PFS with superior PFS after 5 years for low-risk tumors (96.6% vs. 75.0%, p = 0,02). Overall survival was 96.2% after 60 months and 92.0% after 72 months from therapy. Of six documented deaths, five were definitely not and the sixth probably not meningioma-related.

CONCLUSION

Particle radiotherapy is an excellent treatment option for patients with meningiomas of the skull base and can lead to long-term tumor control with minimal side effects. Other prospective studies with longer follow-up will be necessary to further confirm the role of particle radiotherapy in skull base meningioma.