Fractional spinal anaesthesia in high-risk elderly patients for orthopaedic surgery - Case series

Elderly patients coming for orthopaedic surgeries usually have many comorbidities. This makes them potentially vulnerable to haemodynamic instability with a conventional bolus dose of spinal anaesthetic. Fractionating the spinal dose was reported to have haemodynamic stability with a longer duration. Here, we present five cases of high-risk elderly patients with multiple comorbidities who presented for orthopaedic surgeries and were successfully managed with fractional spinal anaesthesia.

Immunogenicity, efficacy, and safety of SARS-CoV-2 vaccine dose fractionation: a systematic review and meta-analysis

BACKGROUND

Dose fractionation of a coronavirus disease 2019 (COVID-19) vaccine could effectively accelerate global vaccine coverage, while supporting evidence of efficacy, immunogenicity, and safety are unavailable, especially with emerging variants.

METHODS

We systematically reviewed clinical trials that reported dose-finding results and estimated the dose-response relationship of neutralizing antibodies (nAbs) of COVID-19 vaccines using a generalized additive model. We predicted the vaccine efficacy against both ancestral and variants, using previously reported correlates of protection and cross-reactivity. We also reviewed and compared seroconversion to nAbs, T cell responses, and safety profiles between fractional and standard dose groups.

RESULTS

We found that dose fractionation of mRNA and protein subunit vaccines could induce SARS-CoV-2-specific nAbs and T cells that confer a reasonable level of protection (i.e., vaccine efficacy > 50%) against ancestral strains and variants up to Omicron. Safety profiles of fractional doses were non-inferior to the standard dose.

CONCLUSIONS

Dose fractionation of mRNA and protein subunit vaccines may be safe and effective, which would also vary depending on the characteristics of emerging variants and updated vaccine formulations.

Hypofractionation in Hepatocellular Carcinoma - The Effect of Fractionation Size

The use of stereotactic body radiotherapy (SBRT) in hepatocellular carcinoma (HCC) has increased over the years. Several prospective studies have demonstrated its safety and efficacy, and randomised trials are underway. The advancement in technology has enabled the transition from three-dimensional conformal radiotherapy to highly focused SBRT. Liver damage is the primary limiting toxicity with radiation, with the incidence of grade 3 varying from 0 to 30%. The reported radiotherapy fractionation schedule for HCC, and in practice use, ranges from one to 10 fractions, based on clinician preference and technology available, tumour location and tumour size. This review summarises the safety and efficacy of various SBRT fractionation schedules for HCC.

Prognostic Value of the Neutrophil-Lymphocyte Ratio in Triple Negative Breast Cancer Patients

OBJECTIVE

To assess the prognostic value of the neutrophil-lymphocyte ratio (NLR) in a cohort of triple-negative breast cancer patients (TNBC) treated in a regional cancer center.

METHODS

The electronic medical records of 214 consecutive patients treated with surgery, chemotherapy, and radiotherapy between 2006 and 2016 were reviewed. The prognostic significance of the NLR for disease-free survival (DFS) and overall survival (OS) was examined in relation to clinical and treatment-related factors. Overall survival and DFS were assessed using the Kaplan-Meier method; Cox semi-parametric regression modelling was used for multivariate analysis.

RESULTS

Ninety patients were eligible; median follow-up was 45.6 months (range, 6-105 months). The 3-year OS rate was 77.9% and the 5-year OS rate 61.7%. Patients with an NLR of ≤1.7 had significantly better DFS (P=0.029) than patients with an NLR>1.7; OS approached statistical significance (P=0.055). When treatment-related factors - significant on univariate analysis - were entered into the multivariate model, only nodal status N2/N3 remained as significant for DFS (P=0.0078) and advanced T-stage (T3, T4) significant for OS (P=0.014).

CONCLUSION

While NLR is associated with survival in TNBC patients on univariate analysis, the prognostic value of NLR is likely due to its association with other clinicopathological factors.

Ultrahypofractionated Radiotherapy for Localised Prostate Cancer: How Far Can We Go?

Following adoption of moderately hypofractionated radiotherapy as a standard for localised prostate cancer, ultrahypofractioned radiotherapy delivered in five to seven fractions is rapidly being embraced by clinical practice and international guidelines. However, the question remains: how low can we go? Can radiotherapy for prostate cancer be delivered in fewer than five fractions? The current review summarises the evidence that radiotherapy for localised prostate cancer can be safely and effectively delivered in fewer than five fractions using high dose rate brachytherapy or stereotactic body radiotherapy. We also discuss important lessons learned from the single-fraction high dose rate brachytherapy experience.

Short-course compared to long-course palliative radiotherapy for oesophageal cancer: a single centre observational cohort study

Background

Common symptoms of oesophageal cancer are dysphagia, pain, and bleeding. These symptoms can be relieved with palliative radiotherapy. The aim of this study was to analyse the outcome of two different palliative radiotherapy schedules.

Methods

We conducted a retrospective cohort study on palliative radiotherapy for oesophageal cancer given at Karolinska University Hospital. Patients included were treated with either short-course (20 Gy in 4 Gy fractions daily, 5 consecutive workdays) or long-course (30–39 Gy in 3 Gy fractions, 10–13 consecutive workdays) palliative external beam radiotherapy between January 2009 and December 2013. The primary endpoint was dysphagia relief and secondary endpoints were adverse events, re-interventions, and overall survival. Cox regression analyses were used to estimate the effect of treatment schedule on survival.

Results

A total of 128 patients received external beam radiotherapy under the study period, of these 75 (58.6%) received short-course radiotherapy and 53 (41.4%) long-course radiotherapy. Sixteen (30.8%) patients experienced dysphagia relief after short-course radiotherapy and 9 (22.0%) patients after long-course radiotherapy (p = 0.341). Acute toxicity was less frequent after short-course radiotherapy than after long-course radiotherapy, particularly oesophagitis (35.4% vs. 56.0%, p = 0.027) and nausea/emesis (18.5% vs. 36.0% p = 0.034). Re-interventions tended to be more common after short-course radiotherapy (32.0%) than after long-course radiotherapy (18.9%) (p = 0.098). There was no difference in overall survival between the two groups.

Conclusions

Short- and long-course palliative radiotherapy for oesophageal cancer were equally effective to relieve dysphagia and no difference was seen in overall survival. Acute toxicity was, however, more frequent and more severe after long-course radiotherapy. Our results suggest that short-course radiotherapy is better tolerated with equal palliative effects as long-course radiotherapy.

Oncolytic adenovirus with hyaluronidase activity that evades neutralizing antibodies: VCN-11

Tumor targeting and intratumoral virus spreading are key features for successful oncolytic virotherapy. VCN-11 is a novel oncolytic adenovirus, genetically modified to express hyaluronidase (PH20) and display an albumin-binding domain (ABD) on the hexon. ABD allows the virus to self-coat with albumin when entering the bloodstream and evade neutralizing antibodies (NAbs). Here, we validate VCN-11 mechanism of action and characterize its toxicity. VCN-11 replication, hyaluronidase activity and binding to human albumin to evade NAbs was evaluated. Toxicity and efficacy of VCN-11 were assessed in mice and hamsters. Tumor targeting, and antitumor activity was analyzed in the presence of NAbs in several tumor models. VCN-11 induced 450 times more cytotoxicity in tumor cells than in normal cells. VCN-11 hyaluronidase production was confirmed by measuring PH20 activity in vitro and in virus-infected tumor areas in vivo. VCN-11 evaded NAbs from different sources and tumor targeting was demonstrated in the presence of high levels of NAbs in vivo, whereas the control virus without ABD was neutralized. VCN-11 showed a low toxicity profile in athymic nude mice and Syrian hamsters, allowing treatments with high doses and fractionated administrations without major toxicities (up to 1.2x10¹¹vp/mouse and 7.5x10¹¹vp/hamster). Fractionated intravenous administrations improved circulation kinetics and tumor targeting. VCN-11 antitumor efficacy was demonstrated in the presence of NAbs against Ad5 and itself. Oncolytic adenovirus VCN-11 disrupts tumor matrix and displays antitumor effects even in the presence of NAbs. These features make VCN-11 a safe promising candidate to test re-administration in clinical trials.

Long-term outcome of Stereotactic Body Radiation Therapy for patient with unresectable liver metastases from colorectal cancer

PURPOSE

To investigate clinical outcome and predicting factors of local failures in patients with colorectal cancer treated for unresectable liver metastases with stereotactic body radiation therapy (SBRT).

METHODS AND MATERIALS

We restrospectively reviewed the medical records of 67 patients treated with the Cyberknife SBRT system for 99 hepatic metastases between January 2007 and December 2015 in our center. In total, 37.5 to 54.0Gy in 3 to 5 fractions were prescribed to the 80% isodose line. Local control (LC), intrahepatic progression incidence, Progression-Free Survival (PFS), Overall Survival (OS) and toxicity were evaluated.

RESULTS

The median follow-up was 47 months (IQR, 28-59 months). The median OS was 53 months, the 2-year OS and PFS rates were 81.4% and 54.0%. The 1- and 2-year LC rates were 86.6% and 72.4%. In the multivariate analysis, the degree of differentiation was the only prognostic factor for LC (HR 0.31, 95% CI, 0.10-0.98, P=0.046). Margin expansion>5mm was not associated with a better LC (HR 0.72, 95% CI, 0.38-1.37, P=0.317). Performans Status≥2 (HR 3.27, 95% CI, 1.07-9.98, P=0.038), chemotherapy for metastases before SBRT (HR 0.36, 95% CI, 0.18-0.75, P=0.006) and regional lymph node at diagnosis (HR 2.19, 95% CI, 1.09-4.43, P=0.029) were independent prognostic factors for OS. We report 2 cases of grade≥3 toxicity (3.0%) - one grade 3 acute nausea and one grade 3 late gastric ulcer.

CONCLUSION

Stereotactic body radiation therapy is an effective and well-tolerated treatment that allow high LC for liver metastases from colorectal cancer during the first two years. A prescription dose of 45Gy in 3 fractions to the 80% isodose line with a risk adapted schedule to respect Organ At Risk constraints allows a low rate of toxicity.

A single institutional experience with central lung stereotactic body radiation therapy demonstrating encouraging results with increased inter-fraction time

Background

Stereotactic body radiation therapy (SBRT) is an effective treatment modality for non-small cell lung cancer (NSCLC); however, there are concerns regarding potential toxicity for centrally located tumors.

Methods

This retrospective study considered patients with SBRT for central lung NSCLC (defined as a tumor within 2 cm of any mediastinal critical structure). The institutional protocol was that patients with central tumors received SBRT less frequently than daily—generally once or twice weekly.

Results

A total of 115 patients with 148 lesions were treated with SBRT to a median 45 [5–60] Gy in 4 [1–5] fractions over a median 5.3 [0–18] days. Many patients treated with this method presented with advanced disease: 58 treatments involved nodal targets, and 42 had stage 3 disease. 52% of patients had chronic obstructive pulmonary disease (COPD), and only 49% had a biopsy, often due to concerns regarding other medical comorbidities. Rates of prior chemotherapy, thoracic surgery, and thoracic radiotherapy were 32%, 21%, and 49%, respectively. Via the Kaplan-Meier method, 2-year overall survival was 65%, and 2-year local control was 77%. Two-year local-progression free survival was 53%, and 2-year progression-survival was 48%. Treatments for stage 3 disease had an impressive 82% 2-year local control that was comparable to early stage treatments. Patients with stage 3 disease had a 2-year overall survival of 59%, which trended towards decreased overall survival compared to early stage patients. There were 13 grade 1 (9%) and 14 grade 2 (9%) toxicities. There were no reported grade ≥3 acute or late toxicities and only 3 cases of pneumonitis.

Conclusions

Our series demonstrates encouraging local control with low rates of toxicity for central lung SBRT, including many stage 3 patients. This may be the result of the relatively large inter-fraction interval. This interval may allow for greater tumor effects (such as reoxygenation) and improved tolerance from normal tissues.

Hypofractionated radiotherapy in the real-world setting: An international ESTRO-GIRO survey

BACKGROUND AND PURPOSE

Multiple large trials have established the non-inferiority of hypofractionated radiotherapy compared to conventional fractionation. This study will determine real-world hypofractionation adoption across different geographic regions for breast, prostate, cervical cancer, and bone metastases, and identify barriers and facilitators to its use.

MATERIALS AND METHODS

An anonymous, electronic survey was distributed from January 2018 through January 2019 to radiation oncologists through the ESTRO-GIRO initiative. Predictors of hypofractionation were identified in univariable and multivariable regression analyses.

RESULTS

2316 radiation oncologists responded. Hypofractionation was preferred in node-negative breast cancer following lumpectomy (82·2% vs. 46·7% for node-positive; p < 0.001), and in low- and intermediate-risk prostate cancer (57·5% and 54·5%, respectively, versus 41·2% for high-risk (p < 0.001)). Hypofractionation was used in 32·3% of cervix cases in Africa, but <10% in other regions (p < 0.001). For palliative indications, hypofractionation was preferred by the majority of respondents. Lack of long-term data and concerns about local control and toxicity were the most commonly cited barriers. In adjusted analyses, hypofractionation was least common for curative indications amongst low- and lower-middle-income countries, Asia-Pacific, female respondents, small catchment areas, and in centres without access to intensity modulated radiotherapy.

CONCLUSION

Significant variation was observed in hypofractionation across curative indications and between regions, with greater concordance in palliation. Using inadequate fractionation schedules may impede the delivery of affordable and accessible radiotherapy. Greater regionally-targeted and disease-specific education on evidence-based fractionation schedules is needed to improve utilization, along with best-case examples addressing practice barriers and supporting policy reform.

Establishment of a New Three-Dimensional Dose Evaluation Method Considering Variable Relative Biological Effectiveness and Dose Fractionation in Proton Therapy Combined with High-Dose-Rate Brachytherapy

Purpose:

The purpose of this study is to evaluate the influence of variable relative biological effectiveness (RBE) of proton beam and dose fractionation has on dose distribution and to establish a new three-dimensional dose evaluation method for proton therapy combined with high-dose-rate (HDR) brachytherapy.

Materials and Methods:

To evaluate the influence of variable RBE and dose fractionation on dose distribution in proton beam therapy, the depth-dose distribution of proton therapy was compared with clinical dose, RBE-weighted dose, and equivalent dose in 2 Gy fractions using a linear-quadratic-linear model (EQD2_LQL). The clinical dose was calculated by multiplying the physical dose by RBE of 1.1. The RBE-weighted dose is a biological dose that takes into account RBE variation calculated by microdosimetric kinetic model implemented in Monte Carlo code. The EQD2_LQL is a biological dose that makes the RBE-weighted dose equivalent to 2 Gy using a linear-quadratic-linear (LQL) model. Finally, we evaluated the three-dimensional dose by taking into account RBE variation and LQL model for proton therapy combined with HDR brachytherapy.

Results:

The RBE-weighted dose increased at the distal of the spread-out Bragg peak (SOBP). With the difference in the dose fractionation taken into account, the EQD2_LQL at the distal of the SOBP increased more than the RBE-weighted dose. In proton therapy combined with HDR brachytherapy, a divergence of 103% or more was observed between the conventional dose estimation method and the dose estimation method we propose.

Conclusions:

Our dose evaluation method can evaluate the EQD2_LQL considering RBE changes in the dose distribution.

Retrospective analysis of safety and efficacy of anti-PD-1 therapy and radiation therapy in advanced melanoma: A bi-institutional study

BACKGROUND AND PURPOSE

Antibodies against programmed cell death protein 1 (PD-1) are standard treatments for advanced melanoma. Palliative radiation therapy (RT) is commonly administered for this disease. Safety and optimal timing for this combination for melanoma has not been established.

MATERIALS AND METHODS

In this retrospective cohort study, records for melanoma patients who received anti-PD-1 therapy at Duke University or Emory University (1/1/2013-12/30/2015) were reviewed. Patients were categorized by receipt of RT and RT timing relative to anti-PD-1.

RESULTS

151 patients received anti-PD-1 therapy. Median follow-up was 12.9 months. Patients receiving RT (n = 85) had worse baseline prognostic factors than patients without RT (n = 66). One-year overall survival (OS) was lower for RT patients than patients without RT (66%, 95% CI: 55-77% vs 83%, 95% CI: 73-92%). One-year OS was 61% for patients receiving RT before anti-PD-1 (95% CI: 46-76%), 78% for RT during anti-PD-1 (95% CI: 60-95%), and 58% for RT after anti-PD-1 (95% CI: 26-89%). On Cox regression, OS for patients without RT did not differ significantly from patients receiving RT during anti-PD-1 (HR 1.07, 95% CI: 0.41-2.84) or RT before anti-PD-1 (HR 0.56, 95% CI: 0.21-1.45). RT and anti-PD-1 therapy administered within 6 weeks of each other was well tolerated.

CONCLUSION

RT can be safely administered with anti-PD-1 therapy. Despite worse baseline prognostic characteristics for patients receiving RT, OS was similar for patients receiving concurrent RT with anti-PD-1 therapy compared to patients receiving anti-PD-1 therapy alone.

Long-term treatment outcomes of patients with primary optic nerve sheath meningioma treated with stereotactic radiotherapy

We analysed the long-term outcomes of patients with primary optic nerve sheath meningioma (ONSM) treated with stereotactic radiotherapy (SRT). 26 patients with primary ONSM were treated with SRT between 2004 and 2013 at a single institution. SRT was delivered with image guidance to a median dose of 50.4 Gy in 28 fractions. 4 patients had prior surgical debulking. At a median radiological follow-up of 68 months, the MRI based tumour control was 100%. Visual acuity improved in 10 (38.4%), remained stable in 10 (38.4%) and was reduced in 6 (23.1%) patients following treatment. Stable or improved vision post-treatment was seen in 92.3% of patients with good pre-treatment vision (best corrected visual acuity 6/18 or better), compared to only 61.5% of patients with poor pre-treatment vision (best corrected visual acuity 6/24 or worse). Overall, the treatment was well tolerated with no Grade 2 or greater acute toxicity. Minimal other ophthalmic complications were seen with only one patient developing late onset Grade 3 radiation retinopathy.

Advanced radiotherapy for metastatic disease-a major stride or a futile effort?

Radiation Oncologists are involved in patient care from cancer diagnosis to the end of life, and 30-40% of radiation courses are delivered with palliative intent. Recent data has supported the use of advanced technology in select metastatic settings with respect to improvements in symptom response, local control, and even survival. Practicing physicians must thus be aware of the appropriate uses of advanced radiation techniques, especially with the development of life-prolonging targeted therapy and immunotherapies for individuals with advanced disease. As patients live longer with metastatic burden clinicians may increasingly encounter complex clinical scenarios that strike a 'middle ground' between purely palliative or curative intent. That is, the situation in which aggressive palliation is warranted to provide durable local control and potentially improve progression free and overall survival. This article is intended to provide a framework that clinicians can utilize when considering treatment options in complex palliative settings. The review begins with an introduction to advanced radiation techniques, their relevance with respect to histology, and the importance of dosing and fractionation. It further explores the data supporting the use of advanced techniques in the setting of brain metastases, lung metastases, non-spine bone metastases, spinal bone metastases, spinal cord compression, and liver metastases. Each of the sections also discusses specific site-related factors to consider that may sway a practitioner toward or against the use of such techniques. Where applicable, outcomes of re-irradiation are also discussed.

Stereotactic Body Radiotherapy for Centrally Located Primary Non-Small-Cell Lung Cancer: A Meta-Analysis

BACKGROUND

The purpose of the study was to evaluate the efficacy and safety of stereotactic body radiotherapy (SBRT) for centrally located, primary non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

Systematic search of 4 databases (PubMed, MEDLINE, EMBASE, and Cochrane Library) was performed for literature published until May 9, 2018. Primary (overall survival [OS] and local control [LC] rates) and secondary (Grade ≥3 toxicity) endpoints were reported.

RESULTS

Thirteen studies encompassing 599 patients with central NSCLCs were included. Median values of T1 tumor proportion, tumor size, and median survival were 55.3% (range, 0%-75%), 3.3 (range, 2.1-4.1) cm, and 26 (range, 14-68.9) months, respectively. Pooled rates of 1-, 2-, and 3-year OS rates were 84.3% (95% confidence interval [CI], 75.7-90.3), 64.0% (95% CI, 52.9-72.2), and 50.5% (95% CI, 39.4-61.5), respectively. Pooled rates of 1-, 2-, and 3-year LC rates were 89.4% (95% CI, 80.8-94.4), 82.2% (95% CI, 71.7-89.4), and 72.2% (95% CI, 55.0-84.7), respectively. Pooled rate of Grade ≥3 complication was 12.0% (95% CI, 7.3-19.0). Meta-regression analyses showed significant positive relationships between biologically equivalent dose using an α/β of 10 Gy in the linear quadratic model (BED_10Gy) and 1- and 2-year LC rates (P < .001 and P < .001), and 1- and 2-year OS rates (P = .0178 and P = .032), and Grade ≥3 complication rate (P = .0029). In subgroup comparisons between BED_10Gy <100 Gy versus ≥100 Gy, 1- and 2-year LC rates were significantly different but not for OS and Grade ≥3 complication rates.

CONCLUSION

Our results suggests that SBRT is potent for tumor control in central NSCLC, although complications should be further minimized through optimization of dose-fractionation scheme and accurate planning. Using BED_10Gy ≥100 Gy yielded higher LC rates, and dose escalation was related to OS, LC, and complications.

An overview on personalisation of radiotherapy prescriptions in locally advanced non-small cell lung cancer: Are we there yet?

Standard of care radiotherapy in LA-NSCLC is 60-66 Gy in 30-33 fractions. However outcomes for these patients are poor with 5-year survival in the range of 10-20%. Randomised controlled trials have shown that dose escalation in a linear fashion does not improve outcomes for all patients, thus there is a need to tailor the prescription to the individual patient. This review assesses the strategies published to personalise the radiation therapy dose prescription in LA-NSCLC. A systematic and scoping search of the literature was performed to identify studies that met the inclusion criteria. 19 relevant studies were identified ranging from prospective clinical trials to mathematically modelled concept studies. Heterogeneity existed between all clinical studies. Nine heterogeneous publications proposed methodology to adapt the dose prescription to the individual patient. A number of encouraging strategies have been identified but fall short of the evidence level required to influence clinical practice.

Clinical outcomes and prognostic factors in cisplatin versus cetuximab chemoradiation for locally advanced p16 positive oropharyngeal carcinoma

OBJECTIVES

Randomized trials evaluating cisplatin versus cetuximab chemoradiation (CRT) for p16+ oropharyngeal cancer (OPC) have yet to report preliminary data. Meanwhile, as a preemptive step toward morbidity reduction, the off-trial use of cetuximab in p16+ patients is increasing, even in those who could potentially tolerate cisplatin. The purpose of this study was to compare the efficacy of cisplatin versus cetuximab CRT in the treatment of p16+ OPC and to identify prognostic factors and predictors of tumor response.

MATERIALS AND METHODS

Cases of p16+ OPC treated with cisplatin or cetuximab CRT at our institution from 2010 to 2014 were identified. Recursive partitioning analysis (RPA) classification was used to determine low-risk (LR-RPA) and intermediate-risk (IR-RPA) groups. Log-rank/Kaplan-Meier and Cox Regression methods were used to compare groups.

RESULTS

We identified 205 patients who received cisplatin (n = 137) or cetuximab (n = 68) CRT in the definitive (n = 178) or postoperative (n = 27) setting. Median follow-up was 3 years. Cisplatin improved 3-year locoregional control (LRC) [92.7 vs 65.4%], distant metastasis-free survival (DMFS) [88.3 vs 71.2%], recurrence-free survival (RFS) [86.6 vs 50.6%], and overall survival (OS) [92.6 vs 72.2%] compared to cetuximab [all p < .001]. Concurrent cisplatin improved 3-year OS for LR-RPA (97.1 vs 80.3%, p < .001) and IR-RPA (97.1 vs 80.3%, p < .001) groupings.

CONCLUSION

When treating p16+ OPC with CRT, the threshold for substitution of cisplatin with cetuximab should be maintained appropriately high in order to prolong survival times and optimize locoregional and distant tumor control. When cetuximab is used in cisplatin-ineligible patients, altered fractionation RT should be considered in an effort to improve LRC.

Propensity score matching analysis of a phase II study on simultaneous modulated accelerated radiation therapy using helical tomotherapy for nasopharyngeal carcinomas

Background

Using propensity score matching method (PSM) to evaluate the feasibility and clinical outcomes of simultaneous modulated accelerated radiation therapy (SMART) using helical tomotherapy (HT) in patients with nasopharyngeal carcinoma (NPC).

Methods

Between August 2007 and January 2016, 381 newly diagnosed NPC patients using HT were enrolled in pre-PSM cohort, including 161 cases in a prospective phase II study (P67.5 study, with a prescription dose of 67.5Gy in 30 fractions to the primary tumour and positive lymph nodes) and 220 cases in a retrospective study (P70 study, with a prescription dose of 70Gy in 33 fractions to the primary tumour and positive lymph nodes). Acute and late toxicities were assessed according to the established RTOG/EORTC criteria and Common Terminology Criteria for Adverse Events (CTCAE) V 3.0. Survival rate were assessed with Kaplan-Meier method, log-rank test and Cox regression.

Results

After matching, 148 sub-pairs of 296 patients were generated in post-PSM cohort. The incidence of grade 3–4 leukopenia, thrombocytopenia and anemia in the P67.5 group was significantly higher than in the P70 study, but no significant different was found in other acute toxicities or late toxicities between the two groups. The median follow-up was 33 months in the P67.5 and P70 group, ranging 12–54 months and 6–58 months, respectively. No significant differences in 3-year local-regional recurrence free survival (LRRFS), distant metastasis-free survival (DMFS), disease free survival (DFS) and overall survival (OS) were observed between the 2 groups. Univariate analysis showed that age, T stage, clinical stage were the main factors effecting survival. Cox proportional hazards model showed that 67.5Gy/30F pattern seemed superior in 3-year OS (HR = 0.476, 95% CI: 0.236-0.957).

Conclusions

Through increasing fraction dose and shortening treatment time, the P67.5 study achieved excellent short-term outcomes and potential clinical benefits, with acceptable acute and late toxicities.

Trial registration

The trial was registered at Chinese Clinical Trial Registry on 5 July 2014 with a registration code of ChiCTRONC-14,004,895.

BioXmark for high-precision radiotherapy in an orthotopic pancreatic tumor mouse model : Experiences with a liquid fiducial marker

BACKGROUND AND PURPOSE

High-precision radiotherapy (RT) requires precise positioning, particularly with high single doses. Fiducial markers in combination with onboard imaging are excellent tools to support this. The purpose of this study is to establish a pancreatic cancer mouse model for high-precision image-guided RT (IGRT) using the liquid fiducial marker BioXmark (Nanovi, Kongens Lyngby, Denmark).

METHODS

In an animal-based cancer model, different volumes of BioXmark (10-50 µl), application forms, and imaging modalities-cone-beam computer tomography (CBCT) incorporated in either the Small Animal Radiation Research Platform (SARRP) or the small-animal micro-CT Scanner (SkyScan; Bruker, Brussels, Belgium)-as well as subsequent RT with the SARRP system were analyzed to derive recommendations for BioXmark.

RESULTS

Even small volumes (10 µl) of BioXmark could be detected by CBCT (SARRP and Skyscan). Larger volumes (50 µl) led to hardening artefacts. The position of BioXmark was monitored at least weekly by CBCT and was stable over 4 months. BioXmark was shown to be well tolerated; no changes in physical condition or toxic side effects were observed in comparison to control mice. BioXmark enabled an exact fusion with the original treatment plan with less hardening artefacts, and minimized the application of contrast agent for fractionated RT.

CONCLUSION

An orthotopic pancreatic tumor mouse model was established for high-precision IGRT using a fiducial marker. BioXmark was successfully tested and provides the perfect basis for improved imaging in high-precision RT. BioXmark enables a unique application method and optimal targeted precision in fractionated RT. Therefore, preclinical trials evaluating novel fractionation regimens and/or combination treatment with high-end RT can be performed.

High-dose-rate brachytherapy as salvage modality for locally recurrent prostate cancer after definitive radiotherapy : A systematic review

PURPOSE

To review the current status of interstitial high-dose-rate brachytherapy as a salvage modality (sHDR BRT) for locally recurrent prostate cancer after definitive radiotherapy (RT).

MATERIALS AND METHODS

A literature search was performed in PubMed using "high-dose-rate, brachytherapy, prostate cancer, salvage" as search terms. In all, 51 search results published between 2000 and 2016 were identified. Data tables were generated and summary descriptions created. The main outcome parameters used were biochemical control (BC) and toxicity scores.

RESULTS

Eleven publications reported clinical outcome and toxicity with follow-up ranging from 4-191 months. A variety of dose and fractionation schedules were described, including 19.0 Gy in 2 fractions up to 42.0 Gy in 6 fractions. The 5‑year BC ranged from 18-77%. Late grade 3 genitourinary and gastrointestinal toxicity was 0-32% and 0-5.1%, respectively.

CONCLUSIONS

sHDR BRT appears as safe and effective salvage modality for the reirradiation of locally recurrent prostate cancer after definitive RT.

Robust image alignment for cryogenic transmission electron microscopy

Cryo-electron microscopy recently experienced great improvements in structure resolution due to direct electron detectors with improved contrast and fast read-out leading to single electron counting. High frames rates enabled dose fractionation, where a long exposure is broken into a movie, permitting specimen drift to be registered and corrected. The typical approach for image registration, with high shot noise and low contrast, is multi-reference (MR) cross-correlation. Here we present the software package Zorro, which provides robust drift correction for dose fractionation by use of an intensity-normalized cross-correlation and logistic noise model to weight each cross-correlation in the MR model and filter each cross-correlation optimally. Frames are reliably registered by Zorro with low dose and defocus. Methods to evaluate performance are presented, by use of independently-evaluated even- and odd-frame stacks by trajectory comparison and Fourier ring correlation. Alignment of tiled sub-frames is also introduced, and demonstrated on an example dataset. Zorro source code is available at github.com/CINA/zorro.

Hypofractionation Is an Acceptable Alternative to Conventional Fractionation in the Treatment of Postlumpectomy Ductal Carcinoma In Situ With Radiotherapy

PURPOSE

The standard dose of postlumpectomy radiotherapy (RT) for ductal carcinoma in situ (DCIS) is 50 Gy in 25 fractions using conventional fractionation (CF). However, in invasive carcinoma, hypofractionation (HF) with 40 to 42.6 Gy in 15 to 16 fractions has largely become a standard of care. The purpose of this study was to review the management of postlumpectomy DCIS in terms of RT dose-fractionation and its impact on local recurrence (LR), in one of the largest Canadian academic centers.

METHODS AND MATERIALS

Between 2003 and 2008, a total of 348 women with DCIS were treated with postlumpectomy RT. Patient characteristics, histopathology, dose-fractionation, use of endocrine therapy, local, regional, contralateral breast recurrences, and cause of death were collected. Local recurrence-free survival was determined. Univariate and multivariate analyses were performed to identify risk factors for LR.

RESULTS

The median age of the cohort was 59 years. Two hundred two (58%) patients received CF and 146 (42%) HF. Initially, the yearly proportion of HF was 34%, but increased up to 68% since 2007. Estrogen receptor was positive in 195 patients, and 43% of those received endocrine therapy. With a median follow-up of 64.8 months, 36 LRs were detected. The 5-year local recurrence-free survival rate was 94% for the HF group versus 91% for the CF group (P = .80). On multivariate analysis, only the use of endocrine therapy showed a trend towards decreasing LR (hazard ratio, 0.44; 95% confidence interval, 0.18-1.08; P = .07).

CONCLUSIONS

The utilization of HF for DCIS postlumpectomy has increased over time and is a valid option as it results in similar rates of local control.

Radiosurgical decompression for benign perioptic tumors causing compressive cranial neuropathies: a feasible alternative to microsurgery?

Several studies have reported the efficacy and safety of hypofractionated stereotactic radiosurgery (hSRS) in the treatment of benign perioptic tumors. This study went further and evaluated the feasibility of hSRS in the treatment of those causing compressive cranial neuropathies (CCNs) among perioptic tumors with special consideration of functional improvement. Twenty-six patients with CCNs (CN II = 19; CN III/IV/VI = 9; CN V = 3) caused by perioptic tumors underwent hSRS between 2011 and 2015. hSRS was delivered in five fractions with a median marginal dose of 27.8 Gy (≈14 Gy in a single fraction, assuming an α/β of three) to a tumor volume of 8.2 ± 8.3 cm³. All tumors except one shrank after treatment, with a mean volume decrease of 35 % (range 4-84 %) during the mean follow-up period of 20 months. In 19 patients (38 eyes) with compressive optic neuropathy, vision improved in 55.3 % of eyes (n = 21), was unchanged in 36.8 % (n = 14), and worsened in 7.9 % (n = 3) (2.6 % after excluding two eyes deteriorated due to transient tumor swelling). A higher conformity index (p = 0.034) and volume of the optic apparatus receiving >23.0 Gy (p = 0.019) were associated with greater tumor shrinkage. A greater decrease in tumor volume (p = 0.035) was associated with a better improvement in vision. Ophthalmoplegia and facial hypesthesia improved in six of nine (66.7 %) and three of three (100 %) patients, respectively. There was no newly developed neurological deficit. Decompressive SRS for benign perioptic tumors causing CCN is feasible using hypofractionation, representing a useful alternative to microsurgical resection.

Preoperative chemoradiation for locally advanced rectal cancer: comparison of three radiation dose and fractionation schedules

Purpose:

The standard radiation dose for patients with locally rectal cancer treated with preoperative chemoradiotherapy is 45–50 Gy in 25–28 fractions. We aimed to assess whether a difference exists within this dose fractionation range.

Materials and Methods:

A retrospective analysis was performed to compare three dose fractionation schedules. Patients received 50 Gy in 25 fractions (group A), 50.4 Gy in 28 fractions (group B), or 45 Gy in 25 fractions (group C) to the whole pelvis, as well as concurrent 5-fluorouracil. Radical resection was scheduled for 8 weeks after concurrent chemoradiotherapy.

Results:

Between September 2010 and August 2013, 175 patients were treated with preoperative chemoradiotherapy at our institution. Among those patients, 154 were eligible for analysis (55, 50, and 49 patients in groups A, B, and C, respectively). After the median follow-up period of 29 months (range, 5 to 48 months), no differences were found between the 3 groups regarding pathologic complete remission rate, tumor regression grade, treatment-related toxicity, 2-year locoregional recurrence-free survival, distant metastasis-free survival, disease-free survival, or overall survival. The circumferential resection margin width was a prognostic factor for 2-year locoregional recurrence-free survival, whereas ypN category was associated with distant metastasis-free survival, disease-free survival, and overall survival. High tumor regression grading score was correlated with 2-year distant metastasis-free survival and disease-free survival in univariate analysis.

Conclusion:

Three different radiation dose fractionation schedules, within the dose range recommended by the National Comprehensive Cancer Network, had no impact on pathologic tumor regression and early clinical outcome for locally advanced rectal cancer.

Hypofractionated radiotherapy for medically inoperable stage I non-small cell lung cancer

BACKGROUND

To investigate the clinical outcomes and toxicity of hypofractionated radiotherapy for medically inoperable stage I non-small cell lung cancer (NSCLC).

METHODS

Patients treated with radiotherapy at a dose of 4-6 Gy per fraction using fixed-field intensity modulated radiotherapy (IMRT) or volumetric-modulated arc therapy (VMAT) at our hospital from June 2005 to December 2013 were analyzed. The total prescription doses ranged from 50-78 Gy with 4-6 Gy per fraction. The median follow-up period was 24 months.

RESULTS

A total of 65 patients with stage I NSCLC were analyzed, including 43 primary NSCLC patients and 22 patients with recurrent or second primary NSCLC. An objective response (complete or partial response) was achieved at six months in 84.6% of patients. The three-year local control rate was 90.8%. Kaplan-Meier estimates of local failure-free, progression-free, overall, and cancer-specific survival rates at three years were 90.3%, 64.3%, 68.9%, and 88.8%, respectively. The rate of symptomatic radiation pneumonitis was 16.9%, and no grade 4-5 toxicity was observed.

CONCLUSION

Favorable local control and outcome was achieved with hypofractionated radiotherapy in patients with inoperable stage I NSCLC with acceptable toxicity. The most common schedule of 6 Gy × 12 fractions may be a promising regimen, and a prospective study is in process.

Radiation Therapy Alone in cT1-3N0 Non-small Cell Lung Cancer Patients Who Are Unfit for Surgical Resection or Stereotactic Radiation Therapy: Comparison of Risk-Adaptive Dose Schedules

PURPOSE

High dose definitive radiation therapy (RT) alone is recommended to patients with cT1-3N0 non-small cell lung cancer, who are unfit for surgery or stereotactic RT. This study was conducted to evaluate the clinical outcomes and cost-effectiveness following RT alone using two different modest hypofractionation dose schemes.

MATERIALS AND METHODS

Between 2001 and 2014, 124 patients underwent RT alone. From 2001 till 2010, 60 Gy in 20 fractions was delivered to 79 patients (group 1). Since 2011, 60 Gy in 20 fractions (group 2, 20 patients), and 60 Gy in 15 fractions (group 3, 25 patients) were selectively chosen depending on estimated risk of esophagitis.

RESULTS

At follow-up of 16.7 months, 2-year rates of local control, progression-free survival, and overall survival were 62.6%, 39.1%, and 59.1%, respectively. Overall survival was significantly better in group 3 (p=0.002). In multivariate analyses, cT3 was the most powerful adverse factor affecting clinical outcomes. Incidence and severity of radiation pneumonitis were not different among groups, while no patients developed grade 2 esophagitis in group 3 (p=0.003). Under current Korean Health Insurance Policy, RT cost per person was 22.5% less in group 3 compared with others.

CONCLUSION

The current study demonstrated that 60 Gy in 15 fractions instead of 60 Gy in 20 fractions resulted in comparable clinical outcomes with excellent safety, direct cost saving, and improved convenience to the patients with tumors located at ≥ 1.5 cm from the esophagus.

Asynchronous data acquisition and on-the-fly analysis of dose fractionated cryoEM images by UCSFImage

Newly developed direct electron detection cameras have a high image output frame rate that enables recording dose fractionated image stacks of frozen hydrated biological samples by electron cryomicroscopy (cryoEM). Such novel image acquisition schemes provide opportunities to analyze cryoEM data in ways that were previously impossible. The file size of a dose fractionated image stack is 20-60 times larger than that of a single image. Thus, efficient data acquisition and on-the-fly analysis of a large number of dose-fractionated image stacks become a serious challenge to any cryoEM data acquisition system. We have developed a computer-assisted system, named UCSFImage4, for semi-automated cryo-EM image acquisition that implements an asynchronous data acquisition scheme. This facilitates efficient acquisition, on-the-fly motion correction, and CTF analysis of dose fractionated image stacks with a total time of ∼60s/exposure. Here we report the technical details and configuration of this system.

[Radiotherapy of bone metastases: Which fractionations?]

First-line palliative radiotherapy for painful bone metastases is an effective treatment whatever its fractionation (single or multiple fractions). It is also indicated after failure or insufficient effect of a first irradiation, or the appearance of new painful site. Other indications are spinal cord compression, either as an adjuvant to surgery or as sole treatment, and after surgery for long bone metastases. The development of high precision techniques (stereotactic conditions) widens the possibility of re-irradiation when tolerance doses to normal tissues have already been delivered. Local control and possibly overall survival could be improved in oligometastatic patients.

Do Biliary Complications after Hypofractionated Radiation Therapy in Hepatocellular Carcinoma Matter?

Purpose

The purpose of this study is to evaluate the efficacy of hypofractionated radiation therapy (RT) in the treatment of unresectable hepatocellular carcinoma (HCC) after failure of transarterial chemoembolization (TACE) or in cases of refractory HCC, and to investigate biliary complications after hypofractionated RT.

Materials and Methods

We retrospectively enrolled patients with unresectable, TACE-unresponsive, or refractory HCC treated with hypofractionated RT between July 2006 and December 2012. The perihilar region was defined as the 1-cm area surrounding the right, left, and the common hepatic duct, including the gallbladder and the cystic duct. Significant elevation of total bilirubin was defined as an increase of more than 3.0 mg/dL, and more than two times that of the previous level after completion of RT.

Results

Fifty patients received hypofractionated RT and 27 (54%) had a tumor located within the perihilar region. The median follow-up period was 24.7 months (range, 4.3 to 95.5 months). None of the patients developed classic radiation disease symptoms, but four patients (8%) showed significant elevation of total bilirubin within 1 year after RT. During follow-up, 12 patients (24%) developed radiologic biliary abnormalities, but only two patients had toxicities requiring intervention. Estimated local progression-free survival, progression-free survival, and overall survival of the patients at 3-year post-hypofractionated RT were 89.7%, 11.2%, and 57.4%, respectively.

Conclusion

Biliary complications associated with a higher dose exposure of hypofractionated RT were minimal, even in the perihilar region. Hypofractionated RT provided excellent local control and may be a valuable option for treatment of unresectable cases of TACE-unresponsive or refractory HCC.

Evaluation of fractionated and repeated sonodynamic therapy by using dual frequency for murine model of breast adenocarcinoma

Background

Sonodynamic therapy (SDT) is a new approach for cancer treatment. Repair by reoxygenation induces cell damage in all treatment which uses photo- and sonosensitizers. In this study, the in vivo antitumor effect of dual-frequency sonication is investigated at low-level intensity and hematoporphyrin (Hp). It is used for the treatment of spontaneous breast adenocarcinoma of Balb/c mice with a variety of dose repetition and fractionation regimes.

Methods

Eighty tumor-bearing mice were divided into eight groups, the control group (A); the sham group (B); the injection of Hp alone group (C); 30-min dual-frequency sonication with Hp injection in one repetition at the first day group (D); two repetitions at the first and sixth days group (E); three repetitions at the first, sixth, and twelfth days group (F); four repetitions at the first, sixth, twelfth, and eighteenth days (30 min/repetition) group (G); and the fractional treatment group treated by dual-frequency sonication and Hp injection at the first, third, sixth, and ninth days (7.5 min/fraction) (H). For each group, the tumor growth delay was calculated during 30 days after treatment. These tumors were studied histopathologically.

Results

The results show that the treatment with ultrasound dose repetition in two, three, and four times (E, F, and G groups) were effective in delaying tumor growth compared with one-time sonication (D group) (p < 0.05). Also, the ultrasound dose fractionation is more effective in decreasing the tumor growth rate compared with the ultrasound dose repetition in four repeats and in one repeat from the 12th to the 30th day (p < 0.05). Histopathological studies indicated that the mitotic activity of tumor cells was reduced following treatment with four fraction and four repetition protocols.

Conclusion

The ultrasound dose fractionation and repetition technique with dual-frequency sonication can have a useful therapeutic effect in sonodynamic therapy with the possibility of use in future clinical applications.

Comparison of once daily radiotherapy to 60 Gy and twice daily radiotherapy to 45 Gy for limited stage small-cell lung cancer

Background

This study was designed to compare toxicities, disease control, and survival outcomes for limited disease small-cell lung cancer (LD-SCLC) treated with once daily (QD) versus twice daily (BID) radiotherapy.

Methods

All of the patients received four to six cycles of platinum plus etoposide. In the QD group, irradiation was given via conventional radiotherapy with a dose of 60 Gy at 2 Gy per once-daily fraction. In the BID group, the dose was 45 Gy at 1.5 Gy per twice-daily fraction.

Results

Data from a total of 143 LD-SCLC patients treated at the Shandong Cancer Hospital & Institute were retrospectively analyzed. Statistically significant differences were found in the rates of both grade 2 or higher esophagitis (P = 0.036) and pneumonitis (P = 0.043) between QD and BID groups, respectively. Grade 3 esophagitis occurred in 6% of patients receiving QD and 19% of those receiving BID therapy. The median overall survival (OS) of all patients was 30.4 months: 29.5 months for QD therapy, and 31.4 months for BID therapy. The two-year OS rate was 43.3% for QD therapy, and 48.8% for BID therapy. The two-year locoregional recurrence-free survival (LRFS) rate was 45% versus 63.4% for the QD group versus the BID group, respectively.

Conclusions

Pneumonitis was more common in the QD group, and esophagitis was more common in the BID group. Although there were no significant differences in OS and LRFS between the QD and BID groups, there was a trend toward improved local control in the BID group.

Radiobiology of tissue reactions

Tissue effects of radiation exposure are observed in virtually all normal tissues, with interactions when several organs are involved. Early reactions occur in turnover tissues, where proliferative impairment results in hypoplasia; late reactions, based on combined parenchymal, vascular, and connective tissue changes, result in loss of function within the exposed volume; consequential late effects develop through interactions between early and late effects in the same organ; and very late effects are dominated by vascular sequelae. Invariably, involvement of the immune system is observed. Importantly, latent times of late effects are inversely dependent on the biologically equieffective dose. Each tissue component and--importantly--each individual symptom/endpoint displays a specific dose-effect relationship. Equieffective doses are modulated by exposure conditions: in particular, dose-rate reduction--down to chronic levels--and dose fractionation impact on late responding tissues, while overall exposure time predominantly affects early (and consequential late) reactions. Consequences of partial organ exposure are related to tissue architecture. In 'tubular' organs (gastrointestinal tract, but also vasculature), punctual exposure affects function in downstream compartments. In 'parallel' organs, such as liver or lungs, only exposure of a significant (organ-dependent) fraction of the total volume results in clinical consequences. Forthcoming studies must address biomarkers of the individual risk for tissue reactions, and strategies to prevent/mitigate tissue effects after exposure.

International patterns of practice in radiotherapy for bone metastases: A review of the literature

PURPOSE

Radiation therapy is the standard treatment for symptomatic bone metastases. Several randomized control trials and meta-analyses have concluded a similar efficacy in pain relief when comparing single versus multiple fraction regimes. However, there continues to be reluctance to conform to published guidelines that recommend a single treatment for the palliation of painful bone metastases. The purpose of this literature review is to summarize international patterns of practice, and to determine if guidelines recommending single fraction treatment have been implemented in clinical care.

METHODS

A literature search was conducted in Ovid Medline, Embase, and Cochrane Central. Search words included, 'bone metastases', 'radiation therapy', 'radiotherapy', 'patterns of practice', and 'dose fractionation'. Both prospective and retrospective studies that investigated the prescription of radiotherapy to bone metastases using actual patient databases were included. Articles were excluded if they investigated hypothetical scenarios.

RESULTS

Six hundred and thirteen results were generated from the literature search. Twenty-six articles met the inclusion criteria. Of these, 11 were Canadian, 8 were European, 6 were American, and 1 was Australian. The use of single fraction radiotherapy (SFRT) ranged from 3% to 75%, but was generally lower in American studies. Choice of fractionation depended on a variety of factors, including patient age, prognosis, site of irradiation, and physician experience.

CONCLUSION

Despite the publication of robust randomized control trials, meta-analyses, and clinical practice guidelines recommending the use of a single treatment to palliate uncomplicated bone metastasis, SFRT is internationally underutilized.

Radiotherapy for the prophylaxis of heterotopic ossification: a systematic review and meta-analysis of published data

INTRODUCTION

Following surgery, the formation of heterotopic ossification (HTO) can limit mobility and impair quality of life. Radiotherapy has been proven to provide efficacious prophylaxis against HTO, especially in high-risk settings.

PURPOSE

The current review aims to determine the factors influencing HTO formation in patients receiving prophylactic radiotherapy.

METHODS

A systematic search of the literature was conducted on Ovid Medline, Embase and the Cochrane Central Register of Controlled Trials. Studies were included if they reported the percentage of sites developing heterotopic ossification after receiving a specified dose of prophylactic radiotherapy. Weighted linear regression analysis was conducted for continuous or categorical predictors.

RESULTS

Extracted from 61 articles, a total of 5464 treatment sites were included, spanning 85 separate study arms. Most sites were from the hip (97.7%), from United States patients (55.2%), and had radiation prescribed postoperatively (61.6%) at a dose of 700cGy (61.0%). After adjusting for radiation site, there was no statistically significant relationship between the percentage of sites developing HTO and radiation dose (p=0.1) or whether radiation was administered preoperatively or postoperatively (p=0.1). Sites with previous HTO formation were more likely to develop recurrent HTO than those without previous HTO formation (p=0.04). There was a statistically significant negative relationship between the HTO development and the cohort mean year of treatment (p=0.007).

CONCLUSION

Decreases in rates of HTO over time in this patient population may be a function of more efficacious surgical regimens and prophylactic radiotherapy.

Investigation of the bystander effect in MRC5 cells after acute and fractionated irradiation in vitro

Radiation-induced bystander effect (RIBE) has been defined as radiation responses observed in nonirradiated cells. It has been the focus of investigators worldwide due to the deleterious effects it induces in nonirradiated cells. The present study was performed to investigate whether acute or fractionated irradiation will evoke a differential bystander response in MRC5 cells. A normal human cell line (MRC5), and a human lung tumor cell line (QU-DB) were exposed to 0, 1, 2, and 4Gy of single acute or fractionated irradiation of equal fractions with a gap of 6 h. The MRC5 cells were supplemented with the media of irradiated cells and their micronucleus frequency was determined. The micronucleus frequency after single and fractionated irradiation did not vary significantly in the MRC5 cells conditioned with autologous or QU-DB cell-irradiated media, except for 4Gy where the frequency of micronucleated cells was lower in those MRC5 cells cultured in the media of QU-DB-exposed with a single dose of 4Gy. Our study demonstrates that the radiation-induced bystander effect was almost similar after single acute and fractionated exposure in MRC5 cells.

Review of international patterns of practice for the treatment of painful bone metastases with palliative radiotherapy from 1993 to 2013

BACKGROUND AND PURPOSE

Numerous randomized controlled trials and meta-analyses have affirmed that single and multiple fractions of radiotherapy provide equally efficacious outcomes in the palliation of painful, uncomplicated bone metastases (UBM). We aim to determine geographic, temporal and ancillary factors that influence the global patterns of practice in this setting.

MATERIALS AND METHODS

A literature search was conducted on Ovid MEDLINE and EMBASE. Studies were included if they disclosed prescription patterns of single fraction radiotherapy, either through hypothetical cases or actual patient data. Weighted analysis of variance was conducted for binary predictors while weighted linear regression analysis was performed for continuous parameters.

RESULTS

Nine hypothetical case studies and thirteen actual patterns of practice articles were included from 301 search results. Radiation oncologists prescribed dose fractionations ranging from 3Gy×1 to 2Gy×30, with a median of 3Gy×10, for the palliation of UBM. Actual data demonstrated a weak, non-significant, negative linear relationship between the use of single fraction radiotherapy and the year of treatment. Geographical location of treatment was a key predictor of prescription patterns.

CONCLUSION

In the last twenty years, there was an overall global reluctance to practice evidence-based medicine by employing single fractions for UBM.

Critical dose and toxicity index of organs at risk in radiotherapy: analyzing the calculated effects of modified dose fractionation in non-small cell lung cancer

To increase the efficacy of radiotherapy for non-small cell lung cancer (NSCLC), many schemes of dose fractionation were assessed by a new "toxicity index" (I), which allows one to choose the fractionation schedules that produce less toxic treatments. Thirty-two patients affected by non resectable NSCLC were treated by standard 3-dimensional conformal radiotherapy (3DCRT) with a strategy of limited treated volume. Computed tomography datasets were employed to re plan by simultaneous integrated boost intensity-modulated radiotherapy (IMRT). The dose distributions from plans were used to test various schemes of dose fractionation, in 3DCRT as well as in IMRT, by transforming the dose-volume histogram (DVH) into a biological equivalent DVH (BDVH) and by varying the overall treatment time. The BDVHs were obtained through the toxicity index, which was defined for each of the organs at risk (OAR) by a linear quadratic model keeping an equivalent radiobiological effect on the target volume. The less toxic fractionation consisted in a severe/moderate hyper fractionation for the volume including the primary tumor and lymph nodes, followed by a hypofractionation for the reduced volume of the primary tumor. The 3DCRT and IMRT resulted, respectively, in 4.7% and 4.3% of dose sparing for the spinal cord, without significant changes for the combined-lungs toxicity (p < 0.001). Schedules with reduced overall treatment time (accelerated fractionations) led to a 12.5% dose sparing for the spinal cord (7.5% in IMRT), 8.3% dose sparing for V20 in the combined lungs (5.5% in IMRT), and also significant dose sparing for all the other OARs (p < 0.001). The toxicity index allows to choose fractionation schedules with reduced toxicity for all the OARs and equivalent radiobiological effect for the tumor in 3DCRT, as well as in IMRT, treatments of NSCLC.

Definitive radiation therapy for early glottic cancer: experience of two fractionation schedules

OBJECTIVES

The authors would report the results of definitive radiation therapy (RT) for early glottic cancer by two different radiation dose schedules.

METHODS

From February of 1995 till June of 2008, 157 patients with T1-2N0 glottic cancer were treated with curative RT at Samsung Medical Center. All patients had squamous cell carcinoma, and there were 89 patients (56.7%) with T1a, 36 (22.9%) with T1b, and 32 (20.4%) with T2. Two different radiation dose schedules were used: 70 Gy in 35 fractions to 64 patients (40.8%, group A); and 67.5 Gy in 30 fractions to 93 patients (59.2%, group B). The median treatment durations were 50 days (range, 44 to 59 days) and 44 days (range, 40 to 67 days) in the groups A and B, respectively.

RESULTS

The median follow-up durations were 85 and 45 months for the groups A and B. No severe late complication of RTOG grade 3 or higher was observed, and there was no difference in acute or chronic complication between the groups. Twenty-four patients experienced treatment failure: local recurrence only in 19 patients; regional recurrence only in one; combined local and regional recurrence in four; and systemic metastasis in none. The overall 5-year disease-free survival and disease-specific survival rates were 84.7% and 94.8%. The disease-free survival rate in the group B was better (78.3% vs. 90.8%, P=0.031). This difference was significant only in T1 stage (83.4% vs. 94.6%, P=0.025), but not in T2 (62.7% vs. 60.6%, P=0.965). Univariate analysis showed that the tumor extent, cord mobility, T-stage, and the dose schedule had significant influence on the disease-free survival, and multivariate analysis showed that only the tumor extent and the dose schedule were associated with the disease-free survival.

CONCLUSION

Superior disease-free survival could be achieved by 2.25 Gy per fraction without increased toxicity over shorter RT duration, when compared with 2.0 Gy per fraction.

Quad shot: a short but effective schedule for palliative radiation for head and neck carcinoma

Background:

To evaluate a 2-day course of palliative radiation in patients diagnosed to have inoperable or metastatic head and neck carcinoma.

Aim:

To evaluate the symptom relief and quality of life in these patients after this short course of radiation.

Settings and Design:

A pilot study was conducted in a tertiary care institute in India.

Materials and Methods:

Fifteen patients with stage IV B/C disease, KPS 50-70, were inducted after informed consent. External radiation was given in 2 days, two fractions per day, 6 h apart to a total dose of 14 Gy. Washington University quality of life questionnaire (QOL) was used for assessing QOL before and after radiation. Patients who had more than 50% regression of disease received a second course of similar radiation. All patients were followed up for a mean duration of 6 months.

Statistical Analysis:

The Wilcoxon signed rank test was used to evaluate the difference between the QOL scores before and after treatment.

Results and Conclusions:

Out of these 15 patients, majority (13) were males and the mean age of the patients was 62 years. After the first course, all patients had good symptom relief, improvement in the QOL, and 13 out of 15 had more than 50% objective response. The short duration of the treatment was favored by the outstation patients and their attendants. It may be concluded that this short course of radiation is an effective tool for palliative radiation and merits a larger randomized trial.

Isoeffect calculations with the linear quadratic and its extensions: An examination of model-dependent estimates at doses relevant to hypofractionation

The linear quadratic is the standard model for calculating isoeffects in the range of conventional dose per fraction. However, the use of hypofractionation and stereotactic body radiation therapy can call for isoeffect calculations for large doses per fraction. The purpose of this work is to investigate the linear quadratic at large doses per fraction. The linear quadratic is compared to models that incorporate effects such as dose protraction, whose purpose is to extend the useful range of the linear quadratic to larger doses. The linear quadratic and extended linear quadratic models are fit to 4 data sets. The model-predicted isoeffects for these data sets are calculated. It is found that the linear quadratic and extended linear quadratic predict different isoeffect curves for certain data sets. However, for these data sets, by appropriate selection of a α/β ratio, the linear quadratic can well approximate the extended linear quadratic models. In particular, it is found that a α/β ratio of 0.5 well approximates the extended linear quadratic isoeffect curve for 2 prostate cell lines for conventional and moderate doses per fraction.