Computational approaches in the estimation of radiobiological damage for human-malignant cells irradiated with clinical proton and carbon beams

PURPOSE

The use of Monte Carlo (MC) simulations capable of reproducing radiobiological effects of ionising radiation on human cell lines is of great importance, especially for cases involving protons and heavier ion beams. In the latter, huge uncertainties can arise mainly related to the effects of the secondary particles produced in the beam-tissue interaction. This paper reports on a detailed MC study performed using Geant4-based approach on three cancer cell lines, the HTB-177, CRL-5876 and MCF-7, that were previously irradiated with therapeutic proton and carbon ion beams.

METHODS

A Geant4-based approach used jointly with analytical calculations has been developed to provide a more realistic estimation of the radiobiological damage produced by proton and carbon beams in tissues, reproducing available data obtained from in vitro cell irradiations. The MC "Hadrontherapy" Geant4 application and the Local Effect Model: LEM I, LEM II and LEM III coupled with the different numerical approaches: RapidRusso (RR) and RapidScholz (RS) were used in the study.

RESULTS

Experimental survival curves are compared with those evaluated using the highlighted Geant4 MC-based approach via chi-square statistical analysis, for the combinations of radiobiological models and numerical approaches, as outlined above.

CONCLUSION

This study has presented a comparison of the survival data from MC simulations to experimental survival data for three cancer cell lines. An overall best level of agreement was obtained for the HTB-177 cells.

Radiotherapy for salivary gland cancer: REFCOR recommendations by the formal consensus method

OBJECTIVE

To determine the indications for radiotherapy in salivary gland cancer and to specify the modalities and target radiation volumes.

MATERIAL AND METHODS

The French Network of Rare Head and Neck Tumors (REFCOR) formed a steering group which drafted a narrative review of the literature published on Medline and proposed recommendations. The level of adherence to the recommendations was then assessed by a rating group, according to the formal consensus method.

RESULTS

Postoperatively, radiotherapy to the primary tumor site±to the lymph nodes is indicated if one or more of the following adverse histoprognostic factors are present (risk>10% of locoregional recurrence): T3-T4 category, lymph node invasion, extraglandular invasion, close or positive surgical margins, high tumor grade, perineural invasion, vascular emboli, and/or bone invasion. Intensity-modulated radiation therapy (IMRT) is the gold standard. For unresectable cancers or inoperable patients, carbon ion hadrontherapy may be considered.

CONCLUSION

Radiotherapy in salivary gland cancer is indicated in postoperative situations in case of adverse histoprognostic factors and for inoperable tumors.

Neutron brachytherapy in the modern era: Indications and evidence

Hadrontherapy is a form of radiation therapy (RT) that relies on heavy particles, such as proton, heavy ions, or neutrons, to enhance anti-tumoral efficacy based on their specific dosimetric and radio-biological properties. Neutrons are characterized by specific radiobiological properties that might deserve greater consideration, including the high linear energy transfer and the low oxygen enhancement ratio. Neutron brachytherapy, relying on interstitial or intracavitary neutron sources, has been developed since the 1950s using Californium-252 (252Cf) as a mixed emitter of fission fast neutrons and γ-photos. However, the place of NBT in the era of modern radiation therapy is yet to be precisely defined. In this systematic review, we aim to provide an up-to-date analysis of current experience and clinical evidence of NBT in the XXI ^th century, by answering the following clinical questions: How is NBT currently delivered? What are the current efficacy data and tolerance profiles of NBT?

Endometrial Cancer: When Upfront Surgery Is Not an Option

Background and Summary: The management of endometrial cancer, in an ever-older population with considerable comorbidity, remains a challenge for gynecological and radiation oncologists. Key Message: The present paper reviews literature data on treatment options for endometrial cancer patients unfit for surgery.

Radioresistant tumours: From identification to targeting

From surviving fraction to tumour curability, definitions of tumour radioresistance may vary depending on the view angle. Yet, mechanisms of radioresistance have been identified and involve tumour-specific oncogenic signalling pathways, tumour metabolism and proliferation, tumour microenvironment/hypoxia, genomics. Correlations between tumour biology (histology) and imaging allow theragnostic approaches that use non-invasive biological imaging using tracer functionalization of tumour pathway biomarkers, imaging of hypoxia, etc. Modelling dose prescription function based on their tumour radio-resistant factor enhancement ratio, related to metabolism, proliferation, hypoxia is an area of investigation. Yet, the delivery of dose painting by numbers/voxel-based radiotherapy with low lineal energy transfer particles may be limited by the degree of modulation complexity needed to achieve the doses needed to counteract radioresistance. Higher lineal energy transfer particles or combinations of different particles, or combinations with drugs and devices such as done with radioenhancing nanoparticles may be promising.

Adenoid Cystic Carcinoma of Bartholin's Gland: What Is the Best Approach?

Background and summary: Among all vulvar cancers, primary adenoid cystic carcinoma (ACC) of Bartholin's gland is a very rare tumor characterized by a slow growth, a high local aggressiveness, and a remarkable recurrence rate. Due to its rarity, treatment remains a challenge for oncologists and gynecological surgeons. Key message: The present paper reports clinical, radiological, and histological features of ACC of Bartholin's gland and reviews the literature data on the treatment options with a particular focus on the potential role of particle radiation therapy.

[Diagnosis, prognosis and treatment of sinonasal carcinomas (excluding melanomas, sarcomas and lymphomas)]

Sinonasal carcinomas account for 3% of ENT cancers. They are subdivided into squamous cell carcinomas (50%), adenocarcinomas [20%, mostly of intestinal type (ITAC)], and more rarely, adenoid cystic carcinomas, olfactory neuroblastomas (=esthesioneuroblastomas), neuroendocrine carcinomas or undifferentiated sinonasal carcinomas (SNUC). The 5-year survival rates are, in descending order, 72% for neuroblastomas, 63% for adenocarcinomas, 50-60% for large-cell neuroendocrine carcinomas, 53% for squamous cell carcinomas, 25-50% for adenoid cystic, 35% for small-cell neuroendocrine carcinomas and 35% for SNUC and newly discovered histologies. Surgery is the main treatment; endoscopic approaches reduce the morbidity with equivalent tumour control. Intensity-modulated radiation therapy (IMRT) is almost systematic. Nodal involvement is rare in ethmoidal adenocarcinomas and adenoid cystic carcinomas; it is intermediate and may justify prophylactic radiotherapy for N0 necks in SNUC, neuroblastoma, squamous cell carcinomas and sinonasal neuroendocrine carcinomas. IMRT or proton therapy is the mainstay of treatment of unresectable disease. Radiotherapy optimization by carbon ion therapy for adenoid cystic carcinomas, or by chemotherapy for all carcinomas with IMRT or proton therapy, is investigated within clinical trials in France. Neoadjuvant chemotherapy is reserved for rapidly progressive disease or histologies with a high metastatic potential such as neuroendocrine carcinomas or SNUC. Given their histologic and molecular specificities and different relapse patterns, an expertise of the REFCOR network, with REFCORpath review, is likely to correct diagnoses, rectify treatments, with an impact on survival.

Comparison of biophysical models with experimental data for three cell lines in response to irradiation with monoenergetic ions

The relative biological effectiveness (RBE) in particle therapy is currently estimated using biophysical models. We compared experimental measurements to the α curves as function of linear energy transfer computed by the Local Effect Model (LEM I-IV), the Microdosimetric Kinetic Model (MKM) and the NanOx model for HSG, V79 and CHO-K1 cells in response to monoenergetic irradiations. Although the LEM IV and the MKM predictions accurately reproduced the trend observed in the data, NanOx yielded a better agreement than the other models for more irradiation configurations. Its χ 2 estimator was indeed the lowest for three over seven considered cases.

The Role of Particle Therapy in the Risk of Radio-induced Second Tumors: A Review of the Literature

One of the most important late side-effects of radiation therapy is the development of radiation-induced secondary malignancies. In the last years, this topic has significantly influenced treatment decision-making as the number of long-term cancer survivors has significantly increased with advances in treatment modalities. All efforts are being made to prevent the incidence of tumors induced by radiation. In this review article we summarize the current knowledge about treatment-related secondary cancers with a particular attention to hadrontherapy.

Brain MR findings in patients treated with particle therapy for skull base tumors

Nowadays, hadrontherapy is increasingly used for the treatment of various tumors, in particular of those resistant to conventional radiotherapy. Proton and carbon ions are characterized by physical and biological features that allow a high radiation dose to tumors, minimizing irradiation to adjacent normal tissues. For this reason, radioresistant tumors and tumors located near highly radiosensitive critical organs, such as skull base tumors, represent the best target for this kind of therapy. However, also hadrontherapy can be associated with radiation adverse effects, generally referred as acute, early-delayed and late-delayed. Among late-delayed effects, the most severe form of injury is radiation necrosis. There are various underlying mechanisms involved in the development of radiation necrosis, as well as different clinical presentations requiring specific treatments. In most cases, radiation necrosis presents as a single focal lesion, but it can be multifocal and involve a single or multiple lobes simulating brain metastasis, or it can also involve both cerebral hemispheres. In every case, radiation necrosis results always related to the extension of radiation delivery field. Multiple MRI techniques, including diffusion, perfusion imaging, and spectroscopy, are important tools for the radiologist to formulate the correct diagnosis. The aim of this paper is to illustrate the possible different radiologic patterns of radiation necrosis that can be observed in different MRI techniques in patients treated with hadrontherapy for tumors involving the skull base. The images of exemplary cases of radiation necrosis are also presented.

Monte Carlo GEANT4-based application for in vivo RBE study using small animals at LNS-INFN preclinical hadrontherapy facility

Preclinical studies represent an important step towards a deep understanding of the biological response to ionizing radiations. The effectiveness of proton therapy is higher than photons and, for clinical purposes, a fixed value of 1.1 is used for the relative biological effectiveness (RBE) of protons considered 1.1. Recent in vitro studies have reported that the RBE along the spread-out Bragg peak (SOBP) is not constant and, in particular, the RBE value increases on the distal part of SOBP. The present work has been carried-out in the perspective of a preclinical hadrontherapy facility at LNS-INFN and was focused on the experimental preparation of an in vivo study concerning the RBE variation along the SOBP. The main purpose of this work was to determine, using GEANT4-based Monte Carlo simulations, the best configuration for small animal treatments. The developed GEANT4 application simulates the proton-therapy beam line of LNS-INFN (CATANA facility) and allows to import the DICOM-CT images as targets. The RBE will be evaluated using a deterministic radiation damage like myelopathy as end-point. In fact, the dose at which the 50% of animals will show the myelopathy is supposed to be LET-dependent. In this work, we studied different treatment configurations in order to choose the best two that maximize the LET difference reducing as much as possible the dose released to healthy tissue. The results will be useful to plan hadrontherapy treatments for preclinical in vivo studies and, in particular, for the future in vivo RBE studies.

Case-report: Metastases in a low-stage middle-graded HCC in cleared HCV infection, non-cirrhotic liver: Surgical therapy

INTRODUCTION

Hepatocellular carcinoma (HCC) is rare in non-cirrhotic liver. Achievement of sustained virological response (SVR) reduces even more the risk.

PRESENTATION OF CASE

Liver resection for small HCC was performed in cleared HCV infection non-cirrhotic 62-year-old man. Methacronous oligometastatic recurrences in intolerant to Nexavar® side-effects patient, were treated by multiple innovative microinvasive approaches: bilateral laparoscopic adrenalectomy, thoracic wall resection, laparoscopic sacrum cryoablation combined with hadron-therapy.

DISCUSSION

Therapies allowed the patient to lead 6 years satisfying QoL with only a small residual presacral disease stable at 8 months.

CONCLUSION

Microinvasive surgery may be a valid resource of therapy in indolent HCC limited distant recurrences.

The Italian Society of Oncological Radiotherapy (AIRO) survey

Hadrontherapy has been in constant progress in the past decades. Due to the increasing interest in this field and the spreading of the technique in Italy and worldwide, the Italian Society of Radiation Oncology surveyed (by an online survey) its members regarding their perception of hadrontherapy. The survey outline addressed different items all related to hadrontherapy, such as: demographics (3 items), personal knowledge (5 items), actual use in clinical practice (5 items), and future perspectives and development (5 items). The survey was filled in by 224 radiation oncologists (RO). Among them, 74.6 % were RO with more than 5 years of clinical practice, and only 10.4 % RO in training. Median age was 46 years (range 27-77). 32.24 % admitted average knowledge about heavy particles radiobiology rationale and 32.42 % about the ongoing particle therapy clinical trials. Radioresistant tumors are perceived as-principal indications for carbon ions in 39.3 % of responders, and pediatric malignancies for protons in 37 %. Re-irradiation is highly recommended for 52.2 %. Strikingly, 38.8 % of participating ROs reported that, in the daily clinical practice, approximately less than 1 out of 10 patients asks to be referred for hadrontherapy. On the other side, 35.7 % claimed need for at least 3 up to 5 particle therapy centers in Italy. Overall, the results of the present survey highlight the interest of the Italian RO community for particle therapy among the other radiotherapy technique. Analysis of our results might picture the clinical attitude of the RO community towards hadrontherapy in Italy, and help in promoting targeted initiatives to spread clinical results and knowledge about technical innovations in this field.

[Nasopharyngeal adenoid cystic carcinoma, a rare but highly challenging disease with unmet therapeutic needs: A case-report and review of the literature]

Nasopharyngeal adenoid cystic carcinoma is a rare tumour. Compared with others nasopharyngeal tumours, it is characterised by slow evolution but it is locally aggressive and has a high tendency to recurrences. Due to the rarity of cases, no consensus exists about treatment approaches. We report the case of 45-year-old-man with a locally advanced adenoid cystic carcinoma. The patient received concurrent chemoradiation and had a good objective response. After one year, he developed a paucisymptomatic lung metastasis. The follow-up showed local recurrence after 3 years. One cycle of chemotherapy was given but poorly supported. Carbon ion radiotherapy was proposed. The aim of this work is to review the literature concerning this rare malignancy and discusses treatment approaches in initial situations and during recurrences.

[What is the level of evidence of new techniques in prostate cancer radiotherapy?]

Prostate cancer radiotherapy has evolved from the old 2D technique to conformal, and then to intensity-modulated radiation therapy (IMRT) and stereotactic radiotherapy. At the same time, image-guidance (IGRT) is routinely used. New techniques such as protontherapy or carbontherapy are being developed with the objective of increased efficacy, decreased treatment duration, toxicity or cost. This review summarizes the evidence-based medicine of new technologies in the treatment of prostate cancer.

Beam monitor detectors for medical applications

Beam monitoring is fundamental for any particle accelerator. In particular, it is a crucial issue in medical applications of particle physics due to the required high precision and reliability. Radioisotope production and cancer radiotherapy require specific beam monitor detectors. In this paper, three recently designed instruments are reviewed. One of them is a newly designed beam monitor detector based on doped silica and optical fibres. It represents a promising solution. This apparatus can be used with various types of beams and for both hadrontherapy and radioisotope production. For this reason, a more detailed description of this multipurpose detector is provided.

Gadolinium-based nanoparticles to improve the hadrontherapy performances

Nanomedicine is proposed as a novel strategy to improve the performance of radiotherapy. High-Z nanoparticles are known to enhance the effects of ionizing radiation. Recently, multimodal nanoparticles such as gadolinium-based nanoagents were proposed to amplify the effects of x-rays and g-rays and to improve MRI diagnosis. For tumors sited in sensitive tissues, childhood cases and radioresistant cancers, hadrontherapy is considered superior to x-rays and g-rays. Hadrontherapy, based on fast ion radiation, has the advantage of avoiding damage to the tissues behind the tumor; however, the damage caused in front of the tumor is its major limitation. Here, we demonstrate that multimodal gadolinium-based nanoparticles amplify cell death with fast ions used as radiation. Molecular scale experiments give insights into the mechanisms underlying the amplification of radiation effects. This proof-of-concept opens up novel perspectives for multimodal nanomedicine in hadrontherapy, ultimately reducing negative radiation effects in healthy tissues in front of the tumor.

FROM THE CLINICAL EDITOR

Gadolinium-chelating polysiloxane nanoparticles were previously reported to amplify the anti-tumor effects of x-rays and g-rays and to serve as MRI contrast agents. Fast ion radiation-based hadrontherapy avoids damage to the tissues behind the tumor, with a major limitation of tissue damage in front of the tumor. This study demonstrates a potential role for the above nanoagents in optimizing hadrontherapy with preventive effects in healthy tissue and amplified cell death in the tumor.