Effect of beam profile measurement on arc therapy plan quality assurance: a case study

We present an example when profile measurement and modeling of an Elekta Agility multileaf collimator (MLC) had a large effect specifically on arc therapy plan quality assurance (QA) results using ArcCheck. ArcCheck absolute dose measurements of these plans were systematically lower than planned by 3–10%. Failing QA results were seen even with unmodulated static and conformal arcs. Furthermore, the effect was found to be dependent on collimator angle, with worse results associated with near‐zero collimator angles. In contrast, step‐and‐shoot QA results were not affected. Changing the beam model to match steeper profile measurements obtained using a different measurement device resolved the problem. This case study demonstrates that conventional gamma index analysis can be sensitive to small profile modeling changes.

Elevated semaphorin5A in systemic lupus erythematosus is in association with disease activity and lupus nephritis

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by extensive immune response, including over-activation of T and B cell development of pathogenic autoantibodies, organ damage induced by the formation and deposition of immune complex and the abnormal elevation of type I interferon. Semaphorin5A (Sema5A) is involved essentially in immune cell regulation and is also implicated in the pathogenesis of autoimmune disorders. We aimed to evaluate the role of Sema5A in patients with SLE. Serum levels of Sema5A were tested by enzyme-linked immunosorbent assay (ELISA) in 152 SLE patients and 48 healthy controls. The message ribonucleic acid (mRNA) expression levels of Sema5A and ADAM metallopeptidase domain 17 (ADAM17) in the peripheral blood mononuclear cells (PBMC) from 43 patients with SLE and 19 healthy controls were detected by the real-time-quantitative polymerase chain reaction (qPCR). Serum Sema5A levels were increased significantly in SLE patients compared with healthy controls (P < 0·001). Elevated levels of Sema5A were correlated positively with 24-h proteinuria excretion (r = 0·558, P < 0·0001), SLE disease activity index (SLEDAI) (r = 0·278, P = 0·0006) and C-reactive protein (CRP) (r = 0·266, P = 0·002), but negatively with planet (PLT) (r = -0·294, P = 0·0003) and complement 3 (C3) (r = -0·287, P = 0·0004) in SLE patients. Patients with elevated Sema5A levels showed higher incidence of rash, serositis and nephritis (P < 0·05 or P < 0·001). Patients with decreased PLT, C3 or positive for proteinuria also showed elevated Sema5A (P < 0·001 or P < 0·05). The mRNA ADAM17 was increased in SLE patients and correlated positively with serum Sema5A levels. Our data demonstrated that elevated serum Sema5A in SLE patients correlated with disease activity and are involved in kidney and blood system damage; ADAM17 might be involved in the release of secreted Sema5A.

Two-stage operation to treat destructive midfoot tuberculosis: 14 cases experience

INTRODUCTION

Tuberculosis (TB) in midfoot is often secondary to tuberculosis elsewhere in the body. The experience and literatures to treat midfoot tuberculosis are rare. Up until now, no successful method is reported to treat midfoot tuberculosis.

HYPOTHESIS

Stage surgery is an effective method to treat midfoot bone TB.

MATERIAL AND METHODS

Between January 2008 to January 2011, 14 patients who were diagnosed midfoot tuberculosis and suffered stage operation were enrolled. All the patients had been diagnosed definitely relying on imaging examination and laboratory tests preoperatively. Two-stage operation was performed to all patients. At the first stage, TB tissue and infective tissue were completely removed and replaced by antibiotic bone cement. Normal foot length and arch would be restored and maintained by K-wires and external fixators. At the second stage, autologous iliac and allogeneic bone graft were used to replace bone cement and by fixed by locking plates. American Orthopaedic Foot and Ankle Society (AOFAS), SF-36 and visual analogue scale (VAS) pain score were recorded at the last follow-up.

RESULTS

The average bone union time was 3.8 (range 3-6) months. There is no case of local recurrence or skin sinus. Neither implant broken nor screw loosen was present in this study. The AOFAS score was increased from 51.7±6.8 (range 43-61) preoperatively to 82.9±3.9 (range 76-90) postoperatively (P<0.001). The SF-36 score increased from 46.1±6.1 preoperatively to 83.1±5.4 postoperatively (P<0.001). The VAS score decreased from 6.1±1.1 preoperatively to 1.4±0.9 points postoperatively (P<0.001).

DISCUSSION

Stage operation is an effective treatment to stage III, IV midfoot tuberculosis.

LEVELS OF EVIDENCE

Level IV, retrospective.

Clinical outcomes of extended versus intermittent administration of piperacillin/tazobactam for the treatment of hospital-acquired pneumonia: a randomized controlled trial

The purpose of this study was to assess the pharmacokinetic (PK) characteristics, clinical efficiency, and pharmacoeconomic parameters of piperacillin/tazobactam administered by extended infusion (EI) or intermittent infusion (II) in the treatment of hospital-acquired pneumonia (HAP) in critically ill patients with low illness severity in China. Fifty patients completed the study, with 25 patients receiving 4/0.5 g piperacillin/tazobactam over 30 min as the II group and 25 patients receiving 4/0.5 g piperacillin/tazobactam over 3 h every 6 h as the EI group. Drug assay was performed using high-performance liquid chromatography (HPLC). The percentage of the dosing interval for which the free piperacillin concentration (%fT) exceeds the minimum inhibitory concentration (MIC) was calculated. The patients' therapy cost, clinical efficiency, and adverse effects were also recorded. %fT>MIC was about 100, 98.73, and 93.04 % in the EI arm versus 81.48, 53.29, and 42.15 % in the II arm, respectively, when the microorganism responsible for HAP had an MIC of 4, 8, and 16 mg/L. The therapy cost in the EI group was lower than that of the II group ($1351.72 ± 120.39 vs. $1782.04 ± 164.51, p = 0.001). However, the clinical success rate, clinical failure rate, and drug-related adverse events did not significantly differ between groups. EI treatment with piperacillin/tazobactam was a cost-effective approach to the management of HAP, being equally clinically effective to conventional II.

Association between IL-10 genetic variations and cervical cancer susceptibility in a Chinese population

We conducted an investigation into the role of the IL-10 polymorphisms -592A/C (rs1800872), -819C/T (rs1800871), and -1082A/G (rs1800896) in cervical cancer risk in a Chinese population. A case-control study was carried out, including 165 newly diagnosed cervical cancer patients and 165 control subjects. The polymerase chain reaction-restriction fragment length polymorphism method was used to genotype the three IL-10 variant loci. Using conditional logistic regression analysis, we observed that homozygous IL-10 -819C/T TT carriers were at significantly increased risk of cervical cancer compared to homozygous CC individuals, with an adjusted odds ratio (OR) of 2.23 and a 95% confidence interval (CI) of 1.16-4.30. Moreover, the CT+TT genotype was significantly associated with cervical cancer in comparison to the wild-type variant (OR = 1.69, 95%CI = 1.04-2.76; P = 0.03). In conclusion, our study suggests that the IL-10 -819C/T genetic variation may contribute to cervical cancer risk in the Chinese population examined.

Simple Factors Associated With Radiation-Induced Lung Toxicity After Stereotactic Body Radiation Therapy of the Thorax: A Pooled Analysis of 88 Studies

PURPOSE

To study the risk factors for radiation-induced lung toxicity (RILT) after stereotactic body radiation therapy (SBRT) of the thorax.

METHODS AND MATERIALS

Published studies on lung toxicity in patients with early-stage non-small cell lung cancer (NSCLC) or metastatic lung tumors treated with SBRT were pooled and analyzed. The primary endpoint was RILT, including pneumonitis and fibrosis. Data of RILT and risk factors were extracted from each study, and rates of grade 2 to 5 (G2+) and grade 3 to 5 (G3+) RILT were computed. Patient, tumor, and dosimetric factors were analyzed for their correlation with RILT.

RESULTS

Eighty-eight studies (7752 patients) that reported RILT incidence were eligible. The pooled rates of G2+ and G3+ RILT from all 88 studies were 9.1% (95% confidence interval [CI]: 7.15-11.4) and 1.8% (95% CI: 1.3-2.5), respectively. The median of median tumor sizes was 2.3 (range, 1.4-4.1) cm. Among the factors analyzed, older patient age (P=.044) and larger tumor size (the greatest diameter) were significantly correlated with higher rates of G2+ (P=.049) and G3+ RILT (P=.001). Patients with stage IA versus stage IB NSCLC had significantly lower risks of G2+ RILT (8.3% vs 17.1%, odds ratio = 0.43, 95% CI: 0.29-0.64, P<.0001). Among studies that provided detailed dosimetric data, the pooled analysis demonstrated a significantly higher mean lung dose (MLD) (P=.027) and V20 (P=.019) in patients with G2+ RILT than in those with grade 0 to 1 RILT.

CONCLUSIONS

The overall rate of RILT is relatively low after thoracic SBRT. Older age and larger tumor size are significant adverse risk factors for RILT. Lung dosimetry, specifically lung V20 and MLD, also significantly affect RILT risk.

Distribution of common pathogens in patients with pyogenic liver abscess in China: a meta-analysis

Pyogenic liver abscess (PLA) is a potentially life-threatening disease in many parts of the world, especially in Asia. The aim of this study was to quantify the proportion of common pathogens in patients with PLA in China, using a meta-analysis method based on systematic review of published studies. Several electronic databases were searched to identify the studies reporting the pathogens of PLA. We performed a meta-analysis to calculate the pooled proportion of pathogens and subgroup analysis among the included studies using R 3.1.1 software. In total, 183 studies were included in our final analysis, Klebsiella spp (54 %), Escherichia spp (29 %), Enterobacter spp (9 %), Proteus spp (6 %) and Pseudomonas spp (5 %) comprised the major gram-negative bacteria. Gram-positive bacteria mainly included Staphylococcus spp (13 %), Streptococcus spp (8 %) and Enterococcus spp (7 %). The distribution of pathogens in PLA patients were different in different economic regions in China. The proportion of Klebsiella spp had an upward tendency in recent years compared to other pathogens. In addition, the proportion of common pathogens in PLA patients with diabetes mellitus (DM) were carried out indicating that the dominant pathogens were Klebsiella spp (66 %), Escherichia spp (21 %) and Enterobacter spp (11 %). This meta-analysis showed that the main pathogens of PLA were Klebsiella spp, Escherichia spp, Staphylococcus spp, and Enterobacter spp in China. To ensure a precise estimate of the epidemiology of the pathogens, further large-scale or even a population-based study is needed.

Role of delta-like ligand-4 in chemoresistance against docetaxel in MCF-7 cells

As Notch receptors have been shown to induce chemoresistance, we hypothesized that delta-like ligand-4 (DLL4), a central Notch signalling ligand, might also participate in chemoresistance in breast cancer. To investigate this issue, overexpression of DLL4 was induced by transfection with expression vectors for DLL4 in the human breast cancer cell line Michigan cancer foundation-7 (MCF-7). It was found that DLL4 could be adaptively upregulated by docetaxel (DOC) treatment in a dose-dependent manner, but Notch1 was unaffected. Overexpression of DLL4 could significantly attenuate the cytotoxic effects of DOC by increasing Bcl-2 expression, while decreasing Bax expression, apoptosis rate and DNA damage. The protective effects of DLL4 made cells acquire chemoresistance against DOC and resulted in cancer cell survival. DLL4 is normally regarded as a regulator of vascular development. Our results expanded the understanding of DLL4. Since DLL4 may play an important role in the process of acquiring chemoresistance, it may be a promising target in overcoming chemoresistance in breast cancer.

Simple Factors Associated With Radiation-Induced Lung Toxicity After Stereotactic Body Radiation Therapy of the Thorax: A Pooled Analysis of 88 Studies

PURPOSE

To study the risk factors for radiation-induced lung toxicity (RILT) after stereotactic body radiation therapy (SBRT) of the thorax.

METHODS AND MATERIALS

Published studies on lung toxicity in patients with early-stage non-small cell lung cancer (NSCLC) or metastatic lung tumors treated with SBRT were pooled and analyzed. The primary endpoint was RILT, including pneumonitis and fibrosis. Data of RILT and risk factors were extracted from each study, and rates of grade 2 to 5 (G2+) and grade 3 to 5 (G3+) RILT were computed. Patient, tumor, and dosimetric factors were analyzed for their correlation with RILT.

RESULTS

Eighty-eight studies (7752 patients) that reported RILT incidence were eligible. The pooled rates of G2+ and G3+ RILT from all 88 studies were 9.1% (95% confidence interval [CI]: 7.15-11.4) and 1.8% (95% CI: 1.3-2.5), respectively. The median of median tumor sizes was 2.3 (range, 1.4-4.1) cm. Among the factors analyzed, older patient age (P=.044) and larger tumor size (the greatest diameter) were significantly correlated with higher rates of G2+ (P=.049) and G3+ RILT (P=.001). Patients with stage IA versus stage IB NSCLC had significantly lower risks of G2+ RILT (8.3% vs 17.1%, odds ratio = 0.43, 95% CI: 0.29-0.64, P<.0001). Among studies that provided detailed dosimetric data, the pooled analysis demonstrated a significantly higher mean lung dose (MLD) (P=.027) and V20 (P=.019) in patients with G2+ RILT than in those with grade 0 to 1 RILT.

CONCLUSIONS

The overall rate of RILT is relatively low after thoracic SBRT. Older age and larger tumor size are significant adverse risk factors for RILT. Lung dosimetry, specifically lung V20 and MLD, also significantly affect RILT risk.

Stereotactic Radiosurgery for Poor Performance Status Patients

PURPOSE

Patients with poor performance status (PS), usually defined as a Karnofsky Performance Status of 60 or less, were not eligible for randomized stereotactic radiosurgery (SRS) studies, and many guidelines suggest that whole-brain radiation therapy (WBRT) is the most appropriate treatment for poor PS patients.

METHODS AND MATERIALS

In this retrospective review of our SRS database, we identified 36 patients with PS of 60 or less treated with SRS for central nervous system (CNS) metastatic disease. PS, as defined by the Karnofsky Performance Status, was 60 (27 patients), 50 (8 patients), or 40 (1 patient). The median number of CNS lesions treated was 3.

RESULTS

Median overall survival (OS) was 7.2 months (range, 0.73-25.6 months). Fifteen patients (41%) were alive at 6 months, and 6 patients (16.6%) were alive at 1 year. There was no difference in OS in patients who underwent previous WBRT. There were no local failures or cases of radiation toxicity. Distant CNS failures were seen in 9 patients (25%).

CONCLUSIONS

Our patients with poor PS had reasonable median OS and relatively low distant CNS failure rates. Patients in this patient population may be ideal candidates for SRS compared with WBRT given the low incidence of distant failure over their remaining lives and the favorable logistics of single-fraction treatment for these patients with debility and their caregivers.

Estimated Risk Level of Unified Stereotactic Body Radiation Therapy Dose Tolerance Limits for Spinal Cord

A literature review of more than 200 stereotactic body radiation therapy spine articles from the past 20 years found only a single article that provided dose-volume data and outcomes for each spinal cord of a clinical dataset: the Gibbs 2007 article (Gibbs et al, 2007(1)), which essentially contains the first 100 stereotactic body radiation therapy (SBRT) spine treatments from Stanford University Medical Center. The dataset is modeled and compared in detail to the rest of the literature review, which found 59 dose tolerance limits for the spinal cord in 1-5 fractions. We partitioned these limits into a unified format of high-risk and low-risk dose tolerance limits. To estimate the corresponding risk level of each limit we used the Gibbs 2007 clinical spinal cord dose-volume data for 102 spinal metastases in 74 patients treated by spinal radiosurgery. In all, 50 of the patients were previously irradiated to a median dose of 40Gy in 2-3Gy fractions and 3 patients developed treatment-related myelopathy. These dose-volume data were digitized into the dose-volume histogram (DVH) Evaluator software tool where parameters of the probit dose-response model were fitted using the maximum likelihood approach (Jackson et al, 1995(3)). Based on this limited dataset, for de novo cases the unified low-risk dose tolerance limits yielded an estimated risk of spinal cord injury of ≤1% in 1-5 fractions, and the high-risk limits yielded an estimated risk of ≤3%. The QUANTEC Dmax limits of 13Gy in a single fraction and 20Gy in 3 fractions had less than 1% risk estimated from this dataset, so we consider these among the low-risk limits. In the previously irradiated cohort, the estimated risk levels for 10 and 14Gy maximum cord dose limits in 5 fractions are 0.4% and 0.6%, respectively. Longer follow-up and more patients are required to improve the risk estimates and provide more complete validation.

Introduction and Clinical Overview of the DVH Risk Map

Radiation oncologists need reliable estimates of risk for various fractionation schemes for all critical anatomical structures throughout the body, in a clinically convenient format. Reliable estimation theory can become fairly complex, however, and estimates of risk continue to evolve as the literature matures. To navigate through this efficiently, a dose-volume histogram (DVH) Risk Map was created, which provides a comparison of radiation tolerance limits as a function of dose, fractionation, volume, and risk level. The graphical portion of the DVH Risk Map helps clinicians to easily visualize the trends, whereas the tabular portion provides quantitative precision for clinical implementation. The DVH Risk Map for rib tolerance from stereotactic ablative body radiotherapy (SABR) and stereotactic body radiation therapy (SBRT) is used as an example in this overview; the 5% and 50% risk levels for 1-5 fractions for 5 different volumes are given. Other articles throughout this issue of Seminars in Radiation Oncology present analysis of new clinical datasets including the DVH Risk Maps for other anatomical structures throughout the body.