Linac-based stereotactic salvage reirradiation for intraprostatic prostate cancer recurrence: toxicity and outcomes.

BACKGROUND: The rates of local failure after curative radiotherapy for prostate cancer (PC) remain high despite more accurate locoregional treatments available, with one third of patients experiencing biochemical failure and clinical relapse occurring in 30-47% of cases. Today, androgen deprivation therapy (ADT) is the treatment of choice in this setting, but with not negligible toxicity and low effects on local disease. Therefore, the treatment of intraprostatic PC recurrence represents a challenge for radiation oncologists. Prostate reirradiation (Re-I) might be a therapeutic possibility. We present our series of patients treated with salvage stereotactic Re­I for intraprostatic recurrence of PC after radical radiotherapy, with the aim of evaluating feasibility and safety of linac-based prostate Re­I. MATERIALS AND METHODS: We retrospectively evaluated toxicities and outcomes of patients who underwent salvage reirradiation using volumetric modulated arc therapy (VMAT) for intraprostatic PC recurrence. Inclusion criteria were age ≥ 18 years, histologically proven diagnosis of PC, salvage Re­I for intraprostatic recurrence after primary radiotherapy for PC with curative intent, concurrent/adjuvant ADT with stereotactic body radiation therapy (SBRT) allowed, performance status ECOG 0-2, restaging choline/PSMA-PET/TC and prostate MRI after biochemical recurrence, and signed informed consent. RESULTS: From January 2019 to April 2022, 20 patients were recruited. Median follow-up was 26.7 months (range 7-50). After SBRT, no patients were lost at follow-up and all are still alive. One- and 2­year progression free survival (PFS) was 100% and 81.5%, respectively, while 2­year biochemical progression-free survival (bFFS) was 88.9%. Four patients (20%) experienced locoregional lymph node progression and were treated with a further course of SBRT. Prostate reirradiation allowed the ADT start to be postponed for 12-39 months. Re­I was well tolerated by all patients and none discontinued the treatment. No cases of ≥ G3 genitourinary (GU) or gastrointestinal (GI) toxicity were reported. Seven (35%) and 2 (10%) patients experienced acute G1 and G2 GU toxicity, respectively. Late GU toxicity was recorded in 10 (50%) patients, including 8 (40%) G1 and 2 (10%) G2. ADT-related side effects were found in 7 patients (hot flashes and asthenia). CONCLUSION: Linac-based SBRT is a safe technique for performing Re­I for intraprostatic recurrence after primary curative radiotherapy for PC. Future prospective, randomized studies are desirable to better understand the effectiveness of reirradiation and the still open questions in this field.

Tomotherapy-based moderate hypofractionation for localized prostate cancer: a mono-institutional analysis.

Background: To date, few studies have been published on image-guided helical tomotherapy (HT) in a moderate hypofractionation of localized PCa. We report outcome and toxicity of localized PCa patients treated with HT-based moderate hypofractionated radiotherapy. Materials and methods: 76 patients were retrospectively analyzed. A total dose of 60 Gy (20 × 3 Gy) or 67.5 Gy (25 × 2.7 Gy) was prescribed. The χ2 test was used to analyze associations between toxicity and dosimetric and clinical parameters. The Cox proportional hazard regression model was used for multivariate analysis. Kaplan-Meier method was used for survival analysis. Results: median follow-up was 42.26 months [interquartile (IQR), 23-76). At 4-year, overall survival (OS) and metastasis-free survival (MFS) were 91% and 89%, respectively. At multivariate analysis, smoking habitude was associated with MFS [hazard ratio (HR) 7.32, 95% CI: 1.57-34.16, p = 0.011]. Acute and late grade ≥ 2 gastro-intestinal (GI) toxicity was observed in 6.5% and 2.6% of patients, respectively. Acute and late grade ≥ 2 genito-urinary (GU) toxicity were 31.5% and 3.9%. Four-year late GI and GU grade ≥ 2 toxicity were 3% and 7%, respectively. Acute GI toxicity was associated with statins medication (p = 0.04) and androgen deprivation therapy (p = 0.013). Acute GU toxicity was associated with the use of anticoagulants (p = 0.029) and antiaggregants (p = 0.013). Conclusions: HT-based moderate hypofractionation shows very low rates of toxicity. Smoking habitude is associated with the risk of developing metastases after radical treatment for localized PCa.

Redetermination of PD-L1 expression after chemio-radiation in locally advanced PDL1 negative NSCLC patients: retrospective multicentric analysis.

Background: Chemoradiation therapy (CRT) is the treatment of choice for locally advanced non-small cell lung cancer (LA-NSCLC). Several clinical trials that combine programmed cell death 1 (PD1) axis inhibitors with radiotherapy are in development for patients with LA-NSCLC. However, the effect of CRT on tumor cells programmed cell death ligand-1 (PD-L1) expression is unknown. Methods: In this multicentric retrospective study, we analyzed paired NSCLC specimens that had been obtained pre- and post-CRT. PD-L1 expression on tumor cells was studied by immunohistochemistry. The purpose of this study was to evaluate the feasibility, risk of complications, and clinical relevance of performing re-biopsy after CRT in patients with PD-L1 negative LA-NSCLC. Results: Overall, 31 patients from 6 centers with PD-L1 negative LA-NSCLC were analyzed. The percentage of tumor cells with PD-L1 expression significantly increased between pre- and post-CRT specimens in 14 patients (45%). Nine patients had unchanged PD-L1 expression after CRT, in five patients the rebiopsy material was insufficient for PD-L1 analysis and in two patients no tumor cells at rebiopsy were found. The post-rebiopsy complication rate was very low (6%). All patients with positive PD-L1 re-biopsy received Durvalumab maintenance after CRT, except one patient who had a long hospitalization for tuberculosis reactivation. Median PFS of patients with unchanged or increased PD-L1 expression was 10 and 16.9 months, respectively. Conclusion: CRT administration can induce PD-L1 expression in a considerable fraction of PD-L1 negative patients at baseline, allowing them receiving the maintenance Durvalumab in Europe. Hence, after a definitive CRT, PD-L1 redetermination should be considered in patients with LA-NSCLC PD-L1 negative, to have a better selection of maintenance Durvalumab candidates.

Sterotactic Ablative Radiotherapy in a Multicentric Series of Oligometastatic SCLC: The SAMOS Cohort.

AIMS: SCLC is the most aggressive lung cancer histology with a 5-year OS <10%. At the diagnosis, almost two-thirds of the SCLC an Extended Disease presentation. Two randomized studies (CASPIAN and ImPower133) demonstrated an OS improvement, when immunotherapy was prescribed as maintenance therapy after standard chemotherapy. To date, SABR has had a limited indication in managing metastatic SCLC, although recent reports proposed it as a valid treatment option in selected patients. We propose a retrospective multicentric analysis of patients treated with SABR for oligometastatic SCLC. METHOD: Data of patients affected by oligometastatic-SCLC treated with SABR between 2017 and 2022 in 11 Italian centers were collected. Clinical and therapeutic variables together with OS and time to next treatment were analyzed. Univariate analysis with Kaplan-Meier curve were calculated, and log-rank test were applied. Cox proportional hazard model was used for multivariate analysis. RESULTS: Data from 93 patients and 132 metastatic lesions were analyzed. The median age was 64 years (36-86) and all but 1 had Performance Status 0 or 1. Fifty-two patients presented ED at diagnosis. The first line treatment was radiochemotherapy in 42%, CHT alone in 24% and CHT-IO in 28%, others treatment accounts for 4% and only 2% of patients underwent best supportive care. Of the 132 lesions treated with SBRT 55 were in brain, 27 in lung, 11 in liver, 10 in lymph nodes, 8 in bones and 20 in adrenal gland. Median OS was 14 months, 1 year-OS and 2 years OS were 53% and 27%, respectively. The median TtNT was 14 months for the entire population. Of all the analyzed variables only, the anatomical site of the metastases and their number showed statistical significance in the univariate analysist, confirmed in the subsequent multivariate. CONCLUSION: SABR seems to play a role in delaying further systemic lines in oligometastatic disease and to extend the use of ongoing treatment in oligoprogressive state. Prospective studies are needed to confirm these findings.

Moderately Hypofractionated Helical Tomotherapy for Prostate Cancer: Ten-year Experience of a Mono-institutional Series of 415 Patients.

BACKGROUND/AIM: Radiotherapy represents an important therapeutic option in the management of prostate cancer (PCa). As helical tomotherapy may improve toxicity outcomes, we aimed to evaluate and report the toxicity and clinical outcomes of localized PCa patients treated with moderately hypofractionated helical tomotherapy. PATIENTS AND METHODS: We retrospectively analyzed 415 patients affected by localized PCa and treated with moderately hypofractionated helical tomotherapy in our department from January 2008 to December 2020. All patients were stratified according to the D'Amico risk classification: low-risk 21%, favorable intermediate-risk 16%, unfavorable intermediate-risk 30.4%, and high-risk 32.6%. The dose prescription for high-risk patients was 72.8 Gy to the prostate (planning tumor volume-PTV1), 61.6 Gy to the seminal vesicles (PTV2), and 50.4 Gy to the pelvic lymph nodes (PTV3) in 28 fractions; for low- and intermediate-risk patients 70 Gy for PTV1, 56 Gy for PTV2, and 50.4 Gy for PTV3 in 28 fractions. Image-guided radiation therapy was performed daily in all patients by mega-voltage computed tomography. Forty-one percent of patients received androgen deprivation therapy (ADT). Acute and late toxicity was assessed according to the National Cancer Institute's Common Terminology Criteria for Adverse Events v.5.0 (CTCAE). RESULTS: Median follow-up was 82.7 months (range=12-157 months) and the median age of patients at diagnosis was 72.5 years (range=49-84 years). The 3, 5, and 7 yr overall survival (OS) rates were 95%, 90%, and 84%, respectively, while 3, 5, and 7 yr disease-free survival (DFS) were 96%, 90%, and 87%, respectively. Acute toxicity was as follows: genitourinary (GU) G1 and G2 in 35.9% and 24%; gastrointestinal (GI) in 13.7% and 8%, with G3 or more acute toxicities less than 1%. The late GI toxicity G2 and G3 were 5.3% and 1%, respectively, and the late GU toxicity G2 and G3 were 4.8% and 2.1%, respectively, and only three patients had a G4 toxicity. CONCLUSION: Hypofractionated helical tomotherapy for PCa treatment appeared to be safe and reliable, with favorable acute and late toxicity rates and encouraging results in terms of disease control.

Prognostic Genomic Tissue-Based Biomarkers in the Treatment of Localized Prostate Cancer.

In localized prostate cancer clinicopathologic variables have been used to develop prognostic nomograms quantifying the probability of locally advanced disease, of pelvic lymph node and distant metastasis at diagnosis or the probability of recurrence after radical treatment of the primary tumor. These tools although essential in daily clinical practice for the management of such a heterogeneous disease, which can be cured with a wide spectrum of treatment strategies (i.e., active surveillance, RP and radiation therapy), do not allow the precise distinction of an indolent instead of an aggressive disease. In recent years, several prognostic biomarkers have been tested, combined with the currently available clinicopathologic prognostic tools, in order to improve the decision-making process. In the following article, we reviewed the literature of the last 10 years and gave an overview report on commercially available tissue-based biomarkers and more specifically on mRNA-based gene expression classifiers. To date, these genomic tests have been widely investigated, demonstrating rigorous quality criteria including reproducibility, linearity, analytical accuracy, precision, and a positive impact in the clinical decision-making process. Albeit data published in literature, the systematic use of these tests in prostate cancer is currently not recommended due to insufficient evidence.

The Use of Cardiac Stereotactic Radiation Therapy (SBRT) to Manage Ventricular Tachycardia: A Case Report, Review of the Literature and Technical Notes.

BACKGROUND: among cardiac arrhythmias, ventricular tachycardia (VT) is one that can lead to cardiac death, although significant progress has been made in its treatment, including the use of implantable cardioverter-defibrillators (ICD) and radiofrequency catheter ablation. Nevertheless, long-term recurrence rates remain in about half of patients and drastically impact the patient's quality of life. Moreover, recurrent ICD shocks are painful and are associated with higher mortality and worsening of heart failure. Recently, more and more experiences are demonstrating potential efficacy in the use of stereotactic body radiotherapy (SBRT) (also called cardiac radio-ablation) to treat this condition. In this paper, we report our experience in the use of cardiac radio-ablation for the treatment of refractory ventricular tachycardia with a focus on the technique used, along with a review of the literature and technical notes. CASE PRESENTATION: an 81-year-old male patient with a long history of non-ischemic dilated cardiomyopathy and mechanical mitral prosthesis underwent a biventricular cardioverter defibrillator implant after atrial ventricular node ablation. At the end of 2021, the number of tachycardias increased significantly to about 10 episodes per day. After failure of medical treatment and conventional RT catheter ablation, the patient was treated with SBRT for a total dose of 25 Gy in a single session at the site of the ectopic focus. No acute toxicity was recorded. After SBRT (follow-up 7 months) no other VT episodes were recorded. CONCLUSION: SBRT appears to be safe and leads to a rapid reduction in arrhythmic storms as treatment for VT without acute toxicity, representing one of the most promising methods for treating VT storms.

Stereotactic Body Radiation Therapy (SBRT) for Oligorecurrent/Oligoprogressive Mediastinal and Hilar Lymph Node Metastasis: A Systematic Review.

INTRODUCTION: Mediastinal or hilar lymph node metastases are a challenging condition in patients affected by solid tumors. Stereotactic body radiation therapy (SBRT) could play a crucial role in the therapeutic management and in the so-called "no-fly zone", delivering high doses of radiation in relatively few treatment fractions with excellent sparing of healthy surrounding tissues and low toxicity. The aim of this systematic review is to evaluate the feasibility and tolerability of SBRT in the treatment of mediastinal and hilar lesions with particular regard to the radiotherapy doses, dose constraints for organs at risk, and clinical outcomes. MATERIALS AND METHODS: Two blinded investigators performed a critical review of the Medline, Web of Knowledge, Google Scholar, Scopus, and Cochrane databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA), starting from a specific question: What is the clinical impact of SBRT for the treatment of oligorecurrent/oligoprogressive mediastinal and hilar metastasis? All retrospective and prospective clinical trials published in English up to February 2022 were analyzed. RESULTS: A total of 552 articles were identified and 12 of them were selected with a total number of 478 patients treated with SBRT for mediastinal or hilar node recurrence. All the studies are retrospective, published between 2015 and 2021 with a median follow-up ranging from 12 to 42.2 months. Studies following SBRT for lung lesions or retreatments after thorax radiotherapy for stage III lung cancer were also included. The studies showed extensive heterogeneity in terms of patient and treatment characteristics. Non-small cell lung cancer was the most frequently reported histology. Different dose schemes were used, with a higher prevalence of 4-8 Gy in 5 or 6 fractions, but dose escalation was also used up to 52 Gy in 4 fractions with dose constraints mainly derived from RTOG 0813 trial. The radiotherapy technique most frequently used was volumetric modulated arc therapy (VMAT) with a median PTV volume ranging from 7 to 25.7 cc. The clinical outcome seems to be very encouraging with 1-year local control (LC), overall survival (OS) and progression-free survival (PFS) rates ranging from 84 to 94%, 53 to 88% and 23 to 53.9%, respectively. Half of the studies did not report toxicity greater than G3 and only five cases of fatal toxicity were reported. CONCLUSIONS: From the present review, it is not possible to draw definitive conclusions because of the heterogeneity of the studies analyzed. However, SBRT appears to be a safe and effective option in the treatment of mediastinal and hilar lymph node recurrence, with a good toxicity profile. Its use in clinical practice is still limited, and there is extensive heterogeneity in patient selection and fractionation schedules. Good performance status, small PTV volume, absence of previous thoracic irradiation, and administration of a high biologically effective dose (BED) seem to be factors that correlate with greater local control and better survival rates. In the presence of symptoms related to the thoracic lymph nodes, SBRT determines a rapid control that lasts over time. We look forward to the prospective studies that are underway for definitive conclusions.

A systematic review and meta-analysis on non-metastatic castration resistant prostate cancer: The radiation oncologist's perspective.

Prostate cancer is the second most common cause of cancer-related mortality in men. In patients undergoing a failure after radical treatment, one of the therapeutic option is androgen deprivation: despite initial response rates, a progression to a state of castration resistance is observed in most of the patients. In the present article, we conducted a systematic review and meta-analysis of all clinical trials assessing treatment for nmCRPC with next-generation androgen receptor inhibitors. We performed a review and meta-analysis of phase III randomized controlled trials comparing new agents (apalutamide, enzalutamide, darolutamide) with placebo as control arm, in the setting of nmCRPC. Patients treated with next-generation ARIs had a 26% reduction in the risk of death compared with placebo; compared with other ARIs, darolutamide had the lowest rate of grade 3 and 4 AEs and the lowest therapy discontinuation rate due to any grade AEs. This meta-analysis shows that treatment with new ARIs is safe and significantly reduces the risk of death and of metastasis onset in nmCRPC patients. Under way studies on new biomarkers such as genomic classifiers will probably allow the stratification in more specific subsets of disease. New imaging modalities such as PSMA-PET have shown greater sensibility and specificity than conventional imaging in metastases detection. All patients were randomized in a 2:1 fashion, with a total of 2,694 who underwent next-generation ARIs (806 apalutamide, 955 darolutamide, 933 enzalutamide) and 1,423 in the placebo arm.

The Role of Interstitial Brachytherapy for Breast Cancer Treatment: An Overview of Indications, Applications, and Technical Notes.

Breast cancer represents the second leading cause of cancer-related death in the female population, despite continuing advances in treatment options that have significantly accelerated in recent years. Conservative treatments have radically changed the concept of healing, also focusing on the psychological aspect of oncological treatments. In this scenario, radiotherapy plays a key role. Brachytherapy is an extremely versatile radiation technique that can be used in various settings for breast cancer treatment. Although it is invasive, technically complex, and requires a long learning curve, the dosimetric advantages and sparing of organs at risk are unequivocal. Literature data support muticatheter interstitial brachytherapy as the only method with strong scientific evidence to perform partial breast irradiation and reirradiation after previous conservative surgery and external beam radiotherapy, with longer follow-up than new, emerging radiation techniques, whose effectiveness is proven by over 20 years of experience. The aim of our work is to provide a comprehensive view of the use of interstitial brachytherapy to perform breast lumpectomy boost, breast-conserving accelerated partial breast irradiation, and salvage reirradiation for ipsilateral breast recurrence, with particular focus on the implant description, limits, and advantages of the technique.

Preliminary report on harmonization of features extraction process using the ComBat tool in the multi-center "Blue Sky Radiomics" study on stage III unresectable NSCLC.

BACKGROUND AND PURPOSE: In the retrospective-prospective multi-center "Blue Sky Radiomics" study (NCT04364776), we plan to test a pre-defined radiomic signature in a series of stage III unresectable NSCLC patients undergoing chemoradiotherapy and maintenance immunotherapy. As a necessary preliminary step, we explore the influence of different image-acquisition parameters on radiomic features' reproducibility and apply methods for harmonization. MATERIAL AND METHODS: We identified the primary lung tumor on two computed tomography (CT) series for each patient, acquired before and after chemoradiation with i.v. contrast medium and with different scanners. Tumor segmentation was performed by two oncological imaging specialists (thoracic radiologist and radio-oncologist) using the Oncentra Masterplan® software. We extracted 42 radiomic features from the specific ROIs (LIFEx). To assess the impact of different acquisition parameters on features extraction, we used the Combat tool with nonparametric adjustment and the longitudinal version (LongComBat). RESULTS: We defined 14 CT acquisition protocols for the harmonization process. Before harmonization, 76% of the features were significantly influenced by these protocols. After, all extracted features resulted in being independent of the acquisition parameters. In contrast, 5% of the LongComBat harmonized features still depended on acquisition protocols. CONCLUSIONS: We reduced the impact of different CT acquisition protocols on radiomic features extraction in a group of patients enrolled in a radiomic study on stage III NSCLC. The harmonization process appears essential for the quality of radiomic data and for their reproducibility. ClinicalTrials.gov Identifier: NCT04364776, First Posted:April 28, 2020, Actual Study Start Date: April 15, 2020, https://clinicaltrials.gov/ct2/show/NCT04364776 .

Personalization in Modern Radiation Oncology: Methods, Results and Pitfalls. Personalized Interventions and Breast Cancer.

Breast cancer, the most frequent malignancy in women worldwide, is a heterogeneous group of diseases, characterized by distinct molecular aberrations. In precision medicine, radiation oncology for breast cancer aims at tailoring treatment according to tumor biology and each patient's clinical features and genetics. Although systemic therapies are personalized according to molecular sub-type [i.e. endocrine therapy for receptor-positive disease and anti-human epidermal growth factor receptor 2 (HER2) therapy for HER2-positive disease] and multi-gene assays, personalized radiation therapy has yet to be adopted in the clinical setting. Currently, attempts are being made to identify prognostic and/or predictive factors, biomarkers, signatures that could lead to personalized treatment in order to select appropriate patients who might, or might not, benefit from radiation therapy or whose radiation therapy might be escalated or de-escalated in dosages and volumes. This overview focuses on what has been achieved to date in personalized post-operative radiation therapy and individual patient radiosensitivity assessments by means of tumor sub-types and genetics.

High-dose-rate brachytherapy with surface applicator in penile cancer.

PURPOSE: An alternative to surgery for penile cancer is radiation therapy which is administered with external beam techniques and/or brachytherapy (BT) either interstitial or using a surface applicator. Here we report our experience in penile cancer patients treated with high-dose-rate (HDR)-BT with the surface technique, analyzing dosimetric parameters and clinical outcomes. METHODS AND MATERIALS: Between June 2016 and December 2019, 7 patients with squamous cell carcinoma of the penis received HDR-BT by means of customized applicators that were constructed using a 3D printer or thermoplastic mask. The total dose was 57 Gy in 19 fractions. RESULTS: Median clinical target volume percentage receiving 95%, 125%, and 150% of the prescribed dose were 93.1% (range 92.2-98.5), 12% (range 7.4-32.2), and 0.24% (range 0-10.8), respectively. Median urethral volumes receiving 90% and 115% of the prescribed dose were 40.2% (range 21.0-83.8) and 0% (range 0-1), respectively. All patients achieved complete remission. No patient developed G3 or G4 acute or late toxicities. No patient experienced urethral stenosis. CONCLUSIONS: Surface HDR-BT in penile cancer is feasible and is associated with a high tolerance profile and good outcomes.

Stereotactic body radiotherapy (SBRT) in combination with drugs in metastatic kidney cancer: A systematic review.

OBJECTIVE: To conduct a systematic review and meta-analysis of the role of SBRTdrug combination in patients affected by mRCC and associated oncologic outcomes and toxicity profiles. EVIDENCE ACQUISITION: We performed a critical review of the Pubmed, Medline, and Embase databases from January 1, 2000 through April 30, 2020 according to the Preferred Reporting Items and Meta-Analyses statement. To assess the overall quality of the literature reviewed, we used a modified Delphi tool. EVIDENCE SYNTHESIS: A total of 6 studies were included, corresponding to a cohort of 216 patients. Tyrosine Kinases Inhibitors were the most widely used drugs in combination with SBRT, being administered in 93% patients. No study reported an increase of radiation-induced toxicity. CONCLUSIONS: SBRT resulted to be safe, without increase in terms of drugs-related adverse events in this setting. Moreover, this approach showed promising clinical outcomes in terms of LC and OS.

Management of prostate cancer radiotherapy during the COVID-19 pandemic: A necessary paradigm change.

PURPOSE: To adapt the management of prostate malignancy in response to the COVID-19 pandemic. METHODS: In according to the recommendations of the European Association of Urology, we have developed practical additional document on the treatment of prostate cancer. RESULTS: Low-Risk Group Watchful Waiting should be offered to patients >75 years old, with a limited life expectancy and unfit for local treatment. In Active Surveillance (AS) patients re-biopsy, PSA evaluation and visits should be deferred for up to 6 months, preferring non-invasive multiparametric-MRI. The active treatment should be delayed for 6-12 months. Intermediate-Risk Group AS should be offered in favorable-risk patients. Short-course neoadjuvant androgen deprivation therapy (ADT) combined with ultra-hypo-fractionation radiotherapy should be used in unfavorable-risk patients. High-Risk Group Neoadjuvant ADT combined with moderate hypofractionation should be preferred. Whole-pelvis irradiation should be offered to patients with positive lymph nodes in locally advanced setting. ADT should be initiated if PSA doubling time is < 12 months in radio-recurrent patients, as well as in low priority/low volume of metastatic hormone sensitive prostate cancer. If radiotherapy cannot be delayed, hypo-fractionated regimens should be preferred. In high priority class metastatic disease, treatment with androgen receptor-targeted agents should be offered. When palliative radiotherapy for painful bone metastasis is required, single fraction of 8 Gy should be offered. CONCLUSIONS: In Covid-19 Era, the challenge should concern a correct management of the oncologic patient, reducing the risk of spreading the virus without worsening tumor prognosis.

Stereotactic Radiotherapy for Brain Metastases: Imaging Tools and Dosimetric Predictive Factors for Radionecrosis.

Radionecrosis (RN) is the most important side effect after stereotactic radiotherapy (SRT) for brain metastases, with a reported incidence ranging from 3% to 24%. To date, there are no unanimously accepted criteria for iconographic diagnosis of RN, as well as no definitive dose-constraints correlated with the onset of this late effect. We reviewed the current literature and gave an overview report on imaging options for the diagnosis of RN and on dosimetric parameters correlated with the onset of RN. We performed a PubMed literature search according to the preferred reporting items and meta-analysis (PRISMA) guidelines, and identified articles published within the last ten years, up to 31 December 2019. When analyzing data on diagnostic tools, perfusion magnetic resonance imaging (MRI) seems to be very useful allowing evaluation of the blood flow in the lesion using the relative cerebral blood volume (rCBV) and blood vessel integrity using relative peak weight (rPH). It is necessary to combine morphological with functional imaging in order to match information about lesion morphology, metabolism and blood-flow. Eventually, serial imaging follow-up is needed. Regarding dosimetric parameters, in radiosurgery (SRS) V12 < 8 cm3 and V10 < 10.5 cm3 of normal brain are the most reliable prognostic factors, whereas in hypo-fractionated stereotactic radiotherapy (HSRT) V18 and V21 are considered the main predictive independent risk factors of RN.