The Role of Carbon Ion Therapy in the Changing Oncology Landscape-A Narrative Review of the Literature and the Decade of Carbon Ion Experience at the Italian National Center for Oncological Hadrontherapy.

BACKGROUND: Currently, 13 Asian and European facilities deliver carbon ion radiotherapy (CIRT) for preclinical and clinical activity, and, to date, 55 clinical studies including CIRT for adult and paediatric solid neoplasms have been registered. The National Center for Oncological Hadrontherapy (CNAO) is the only Italian facility able to accelerate both protons and carbon ions for oncological treatment and research. METHODS: To summarise and critically evaluate state-of-the-art knowledge on the application of carbon ion radiotherapy in oncological settings, the authors conducted a literature search till December 2022 in the following electronic databases: PubMed, Web of Science, MEDLINE, Google Scholar, and Cochrane. The results of 68 studies are reported using a narrative approach, highlighting CNAO's clinical activity over the last 10 years of CIRT. RESULTS: The ballistic and radiobiological hallmarks of CIRT make it an effective option in several rare, radioresistant, and difficult-to-treat tumours. CNAO has made a significant contribution to the advancement of knowledge on CIRT delivery in selected tumour types. CONCLUSIONS: After an initial ramp-up period, CNAO has progressively honed its clinical, technical, and dosimetric skills. Growing engagement with national and international networks and research groups for complex cancers has led to increasingly targeted patient selection for CIRT and lowered barriers to facility access.

The Normal, the Radiosensitive, and the Ataxic in the Era of Precision Radiotherapy: A Narrative Review.

(1) Background: radiotherapy is a cornerstone of cancer treatment. When delivering a tumoricidal dose, the risk of severe late toxicities is usually kept below 5% using dose-volume constraints. However, individual radiation sensitivity (iRS) is responsible (with other technical factors) for unexpected toxicities after exposure to a dose that induces no toxicity in the general population. Diagnosing iRS before radiotherapy could avoid unnecessary toxicities in patients with a grossly normal phenotype. Thus, we reviewed iRS diagnostic data and their impact on decision-making processes and the RT workflow; (2) Methods: following a description of radiation toxicities, we conducted a critical review of the current state of the knowledge on individual determinants of cellular/tissue radiation; (3) Results: tremendous advances in technology now allow minimally-invasive genomic, epigenetic and functional testing and a better understanding of iRS. Ongoing large translational studies implement various tests and enriched NTCP models designed to improve the prediction of toxicities. iRS testing could better support informed radiotherapy decisions for individuals with a normal phenotype who experience unusual toxicities. Ethics of medical decisions with an accurate prediction of personalized radiotherapy's risk/benefits and its health economics impact are at stake; (4) Conclusions: iRS testing represents a critical unmet need to design personalized radiotherapy protocols relying on extended NTCP models integrating iRS.

A Dosiomics Analysis Based on Linear Energy Transfer and Biological Dose Maps to Predict Local Recurrence in Sacral Chordomas after Carbon-Ion Radiotherapy.

Carbon Ion Radiotherapy (CIRT) is one of the most promising therapeutic options to reduce Local Recurrence (LR) in Sacral Chordomas (SC). The aim of this work is to compare the performances of survival models fed with dosiomics features and conventional DVH metrics extracted from relative biological effectiveness (RBE)-weighted dose (DRBE) and dose-averaged Linear Energy Transfer (LETd) maps, towards the identification of possible prognostic factors for LR in SC patients treated with CIRT. This retrospective study included 50 patients affected by SC with a focus on patients that presented a relapse in a high-dose region. Survival models were built to predict both LR and High-Dose Local Recurrencies (HD-LR). The models were evaluated through Harrell Concordance Index (C-index) and patients were stratified into high/low-risk groups. Local Recurrence-free Kaplan-Meier curves were estimated and evaluated through log-rank tests. The model with highest performance (median(interquartile-range) C-index of 0.86 (0.22)) was built on features extracted from LETd maps, with DRBE models showing promising but weaker results (C-index of 0.83 (0.21), 0.80 (0.21)). Although the study should be extended to a wider patient population, LETd maps show potential as a prognostic factor for SC HD-LR in CIRT, and dosiomics appears to be the most promising approach against more conventional methods (e.g., DVH-based).

How LEM-based RBE and dose-averaged LET affected clinical outcomes of sacral chordoma patients treated with carbon ion radiotherapy.

PURPOSE/OBJECTIVE: To understand the role of relative biological effectiveness (RBE) and dose-averaged linear energy transfer (LETd) distributions in the treatment of sacral chordoma (SC) patients with carbon ion radiotherapy (CIRT). MATERIAL/METHODS: Clinical plans of 50 SC patients consecutively treated before August 2018 with a local effect model-based optimization were recalculated with the modified microdosimetric kinetic RBE model (mMKM). Twenty-six patients were classified as progressive disease and the relapse volume was contoured on the corresponding follow-up diagnostic sequence. The remaining 24 patients populated the control group. Target prescription dose (DRBE|50%), near-to-minimum- (DRBE|95%) and near-to-maximum- (DRBE|2%) doses were compared between the two cohorts in both RBE systems. LETd distribution was evaluated for in-field relapsed cases with respect to the control group. RESULTS: Target DMKM|50% and DMKM|95% were respectively 10% and 18% lower than what we aimed at. Dosimetric evaluators showed no significant difference, in neither of the RBE frameworks, between relapsed and control sets. Half of the relapse volumes were located in a well-covered high dose region. On average, over these cases, median target LETd was significantly lower than the control cohort mean value (27 vs 30 keV/µm). Most notably, the volume receiving dose from high-LET particles (>50 keV/µm) lay substantially below recently reported data in the literature. CONCLUSION: A combined multi model RBE- and LET-based optimization could play a key role in the enhancement of the therapeutic ratio of CIRT for large radioresistant tumors such as sacral chordomas.

Recommendation for the contouring of limbic system in patients receiving radiation treatment: A pictorial review for the everyday practice and education.

AIMS: The limbic circuit (LC) is devoted to linking emotion to behavior and cognition. The injury this system results in post-RT cognitive dysfunction. The aim of this study is to create the first radiation oncologist's practical MR-based contouring guide for the delineation of the LC for the everyday clinical practice and education. METHODS: An anonymized diagnostic 3.0 T T1-weighted BRAVO MRI sequence from a healthy patient with typical brain anatomy was used to delineate LC. For each structure key anatomical contours were completed by radiation oncologists, along with a neuro-radiologist to generate the final version of the LC atlas. RESULTS: a step-by-step MR-based atlas of LC was created. Key structures of the LC, such as, cingulate gyrus, fornix, septal region, mammillary bodies, thalamus and the hippocampal-amygdala formation were contoured. CONCLUSIONS: This article provides the recommendations for the first contouring atlas of LC in the setting of patients receiving RT and education.

Particle Beam Therapy Tolerance and Outcome on Patients with Autoimmune Diseases: A Single Institution Matched Case-Control Study.

It is unclear whether autoimmune diseases (ADs) may predispose patients to higher radiation-induced toxicity, and no data are available regarding particle therapy. Our objective was to determine if cancer patients with ADs have a higher incidence of complications after protons (PT) or carbon ion (CIRT) therapy. METHODS: In our retrospective monocentric study, 38 patients with ADs over 1829 patients were treated with particle therapy between 2011 and 2020. Thirteen patients had collagen vascular disease (CVD), five an inflammatory bowel disease (IBD) and twenty patients an organ-specific AD. Each patient was matched with two control patients without ADs on the basis of type/site of cancer, type of particle treatment, age, sex, hypertension and/or diabetes and previous surgery. RESULTS: No G4-5 complications were reported. In the AD group, the frequency of acute grade 3 (G3) toxicity was higher than in the control group (15.8% vs. 2.6%, p = 0.016). Compared to their matched controls, CVD-IBD patients had a higher frequency of G3 acute complications (27.7 vs. 2.6%, p = 0.002). There was no difference between AD patients (7.9%) and controls (2.6%) experiencing late G3 toxicity (p = 0.33). The 2 years disease-free survival was lower in AD patients than in controls (74% vs. 91%, p = 0.01), although the differences in terms of survival were not significant. CONCLUSIONS: G3 acute toxicity was more frequently reported in AD patients after PT or CIRT. Since no severe G4-G5 events were reported and in consideration of the benefit of particle therapy for selected cancers, we conclude that particle therapy should be not discouraged for patients with ADs. Further prospective studies are warranted to gain insight into toxicity in cancer patients with ADs enrolled for particle therapy.

One-week vaginal brachytherapy schedule as exclusive adjuvant post-operative treatment in intermediate- and high-intermediate-risk endometrial cancer patients.

PURPOSE: The aim of the study was to report survival outcomes and toxicities incidence by using one-week vaginal brachytherapy (VBT) schedule in intermediate- and high-intermediate-risk endometrial cancer patients. MATERIAL AND METHODS: One hundred and eight patients were treated with exclusive high-dose-rate (HDR) brachytherapy short schedule (7 Gy/fraction/every other day/1 week). Acute and late rectal, urinary, and vaginal toxicities were recorded according to radiation therapy oncology group (RTOG) scores and late effects normal tissue task force - subjective, objective, management, analytic (LENT-SOMA) scores, respectively. Overall survival (OS), cause specific survival (CSS), and disease-free survival (DFS) were evaluated. RESULTS: Median follow-up was 44 months (range, 6-117 months). The 5-year OS, CSS, and DFS rates were 92.7%, 96.4%, and 89.5%, respectively. Seven of 108 (6.5%) patients relapsed after a median time of 31 months (range, 5-56 months). Death occurred in 6 patients. Four patients died for intercurrent causes without an evidence of disease. Acute bladder toxicity G1-G2 was reported in 11 of 108 (10%) patients, vaginal toxicity G1-G2 in 6 of 108 (5.5%), and gastrointestinal toxicity was observed in 3 of 108 (3%) patients. Late bladder and gastrointestinal G1 toxicities were reported in 4 of 108 (4%) and 1 of 108 (1%) patients, respectively. Late vaginal toxicity (G1-G2) was recorded in 3 of 108 (3%) cases. No grade 3-4 bladder, vaginal, and gastrointestinal toxicities were noted. CONCLUSIONS: Exclusive short course adjuvant VBT is an effective treatment in patients with early-stage endometrial cancer and provides good outcomes in terms of disease local control and DFS, with low rates of toxicity profile.

Are we ready for a paradigm shift from high-dose conventional to moderate hypofractionated radiotherapy in intermediate-high risk prostate cancer? A systematic review of randomized controlled trials with trial sequential analysis.

AIM: to evaluate efficacy and late toxicity of moderate hypofractionated (HFRT) over high-dose (>76 Gy) conventional radiotherapy (CRT) in a non-inferiority perspective. METHODS: Randomized controlled trials (RCTs) were included. HFRT regimens were deemed non-inferior to high-dose CRT if the computed CI for the overall RR did not exceed the non-inferiority margin of 7%. RESULTS: When the prespecified margin, corresponding to a critical RR of 0.930 for CCS, OS and BFS, was used all efficacy outcomes satisfied the criteria for the non-inferiority analysis indicating the non-inferiority of HFRT regimens over high-dose CRT in the medium term period. Differently, the evidence concerning the late toxicity was inconclusive. CONCLUSIONS: Noninferiority analysis indicates that moderate HFRT regimes are non-inferior over high-dose CRT in the medium-term. Inconclusive is the evidence for the late toxicity. Longer follow-up will provide a more clear answer concerning the non-inferiority of HFRT regimens in the long-term period.