Inverse-probability weighted and propensity score-based analysis of long-term clinical outcomes comparing 3D conformal radiotherapy (3DCRT) with intensity-modulated radiation therapy (IMRT) in the treatment of esophageal cancer

e14548

Background: IMRT has clear dosimetric advantages in the sparing of normal tissues when compared to the more conventional 3DCRT technique for the treatment of esophageal cancer, but there is currently no clinical outcomes evidence to support the use of IMRT. We hypothesized that the theoretical advantages of IMRT should translate to clinical outcomes benefits compared to 3DCRT. Methods: We analyzed a cohort of 676 patients (3DCRT=413, IMRT=263) treated with chemoradiation with or without surgery between 1998-2008. To correct for potential bias inherent in observational studies, we employed inverse probability of treatment weighted (IPW) methods based on propensity scores. Treatment probabilities (propensity scores) were estimated using logistic regression. Results: IMRT patients were less likely to receive induction chemotherapy and had poorer performance status. A fitted multivariate IPW-adjusted Cox model showed that overall survival was significantly associated with age, KPS, having surgery, tumor location, stage, having PET for staging, and radiation modality. Compared to IMRT, 3DCRT patients had a significantly greater risk of dying (72.6% vs 52.9%, IPW log rank test: p<0.0001) and for local-regional recurrence (LRR) (p=0.0038). The improvement in LRR was only apparent in the non-surgically treated patients due to better tumor control in the primary site, but not in the recurrence in regional nodal sites. There was no difference in cancer-specific mortality, distant metastasis, or postoperative deaths between the two groups. An increased cumulative incidence of cardiac deaths was seen in the 3DCRT group (p=0.049), but the cause of most deaths were unknown (5 year estimate: 11.7% in 3DCRT vs 5.4% in IMRT, Gray’s test, p=0.0029). Analyses using propensity score as a covariate gave very similar results. Conclusions: Our results indicate IMRT improves treatment outcomes in the management of esophageal cancer when compared to 3DCRT. These results, while retrospective, support the use of IMRT for the treatment of esophageal cancer.

Outcome of 58 trimodality-eligible esophagogastric cancer (EC) patients who achieved clinical complete response (cCR) after preoperative chemoradiation but then declined surgery

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Background: For patients with EC who can withstand surgery, the preferred therapy is trimodality. However, after achieving a cCR (defined as post-chemoradiation negative endoscopic biopsy for cancer and post-chemoradiation physiologic FDG uptake by PET), some patients are tempted to decline surgery. Literature is sparse on the outcome of such patients. Methods: Between 2002 and 2011, we identified 621 trimodality-eligible EC patients in our prospective database. All patients had to be trimodality-elgible and must have received preoperative chemoradiation and completed preoperative staging that included a repeat endoscopic biopsy and PET-CT prior to surgery among other routine tests. Results: Of 621 trimodality-eligible patients identified, 58 patients declined surgery after completing chemoradiation. All patients had a cCR. The median age was 69 (range, 47-85). Male (84.5%) and Caucasian (91.4%) were dominant. Baseline stage was II (44.8%) or III (51.7%) and histology was adenocarcinoma (67.2%) or squamous cell carcinoma (29.3%). 40 patients remain alive at a median follow up of 50.4 months (95% CI, 38.6-62.1). 5-year OS and relapse-free survival were 56.7±9.0% and 32.9±7.7%. Of 12 patients with local recurrence during surveillance, 11 had salvage resection. Conclusions: Although, the outcome of EC patients with cCR who declined surgery appears reasonable, in the absence of a validated prediction/prognosis model, only trimodality therapy must be encouraged for trimodality-eligible patients. Supported by UT M. D. Anderson Cancer Center grants and generous donors.

Association of clinical complete response (cCR) after preoperative chemoradiation and pathological complete response (pathCR) in patients with gastroesophageal cancer (GEC) and indispensability of trimodality therapy (TMT)

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Background: TMT strategy has the highest level-1 evidence for treating localized GEC. High rates of cCR (defined as post-chemoradiation negative endoscopic biopsy and physiologic uptake on PET) are common and have questioned the benefit from surgery in patients with cCR after chemoradiation. We hypothesized that cCR would be associated with a high rate of pathCR than < cCR. Methods: The data were analyzed retrospectively in 563 patients who had esophagectomy for GEC in between 2002 and 2010 at UTMDACC. Among them, 284 had TMT and post-chemoradiation endoscopic biopsies and PET (before surgery). Multiple statistical methods were used. Results: Of these 284 TMT patients, 218 (77%) patients achieved a cCR. However, only 67 (31%) of 218 had a pathCR. The sensitivity of cCR for pathCR was 97.1 % (67/69) but the specificity was low, 29.8 % (64/215). Intriguingly, 66 patients who had < cCR, only 2 patients (3%) had a pathCR. The difference in the rate of pathCR between the cCR and < cCR groups was significant (P < 0.001). Conclusions: Our data show that cCR is frequent after chemoradiation but the pathCR rate is not high and it is associated with specificity that is too low for clinical implementation. Therefore, all TMT-eligible patients, irrespective of the achievement of cCR or < cCR must be encouraged to undergo surgery. Therapies that overcome chemoradiation resistance and could increase the pathCR rate are needed for esophageal preservation in select GEC patients. Supported by UTMDACC and generous donors. [Table: see text]

Abstract 207: Casitas B-lineage lymphoma-3 is an epigenetically regulated gene whose knockdown induces mesenchymal to epithelial transition and enhances erlotinib sensitivity in lung cancer cell lines

Casitas B-lineage lymphoma (Cbl) proteins are E3 ubiquitin ligases and multifunctional adaptor proteins that are implicated in the regulation of signal transduction in various cell types and in response to different stimuli. Cbl-3 is a distinct member of this family of 3 genes that is specifically expressed in the epithelial lining of organs, particularly the bronchial airways, whose function, especially in cancer cells, is relatively unknown. Here we report that Cbl-3 expression and promoter CpG island DNA methylation differed profoundly in epithelial compared to mesenchymal-like lung cancer cells. 5-azacytidine treatment, as well as DNA methyltransferase-1 (DNMT1) KD (but not DNMT-3a or 3b) enhanced promoter demethylation and Cbl-3 gene expression. Knock down (KD) of Cbl-3 in mesenchymal-like lung cancer cell lines strongly enhanced EGFR expression and activated downstream pathways. As a result, cells that were normally resistant to erlotinib became greatly sensitized to drug treatment by Cbl-3 KD. Additionally, Cbl-3 KD inhibited cellular migration and increased cellular adhesion to the extra cellular matrix (ECM) as well as promoted cell-to-cell interaction through enhanced E-Cadherin and FAK expression. These alterations suggested a mesenchymal to epithelial transition (MET) conferred by Cbl-3 KD. Take together, this data provided new insights into Cbl-3 gene regulation and elucidated a potential role of Cbl-3 in EGFR signaling in the context of EMT in lung cancer cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 207. doi:1538-7445.AM2012-207

Prognostic impact of radiation therapy to the primary tumor in patients with non-small cell lung cancer and oligometastasis at diagnosis

PURPOSE

We investigated prognostic factors associated with survival in patients with non-small cell lung cancer (NSCLC) and oligometastatic disease at diagnosis, particularly the influence of local treatment to the primary site on prognosis.

METHODS AND MATERIALS

From January 2000 through June 2011, 78 consecutive patients with oligometastatic NSCLC (<5 metastases) at diagnosis underwent definitive chemoradiation therapy (≥45 Gy) to the primary site. Forty-four of these patients also received definitive local treatment for the oligometastases. Survival outcomes were estimated using the Kaplan-Meier method, and risk factors were identified by univariate and multivariate analyses.

RESULTS

Univariate Cox proportional hazard analysis revealed better overall survival (OS) for those patients who received at least 63 Gy of radiation to the primary site (P=.002), received definitive local treatment for oligometastasis (P=.041), had a Karnofsky performance status (KPS) score >80 (P=.007), had a gross tumor volume ≤124 cm³ (P=.002), had adenocarcinoma histology (P=.002), or had no history of respiratory disease (P=.016). On multivariate analysis, radiation dose, performance status, and tumor volume retained significance (P=.004, P=.006, and P<.001, respectively). The radiation dose also maintained significance when patients with and without brain metastases were analyzed separately.

CONCLUSIONS

Tumor volume, KPS, and receipt of at least 63 Gy to the primary tumor are associated with improved OS in patients with oligometastatic NSCLC at diagnosis. Our results suggest that a subset of such patients may benefit from definitive local therapy.

Adiabatically slow and adiabatically fast driven ratchets

We revisit two known models of deterministically driven ratchets, which exhibit high energetic efficiency, with the goal to uncover similarities and differences in the principles of their operation. Both the models rely on adiabaticity of the potential change process, however, the adiabaticity that we deal with in the two cases is of different types, slow and fast. It is shown that in the former (latter) case the drift velocity is an even (odd) functional of the potential, with the notable consequence that for the adiabatically slow driven ratchet the necessary symmetry breaking occurs only due to time-dependent parametric perturbations, while the spatial asymmetry of the potential is a mandatory condition for the adiabatically fast driven ratchet to operate. To treat energetic characteristics, the models are restated in terms of traveling potential ratchets. With such an approach, we find that in these cases (i) the conditions of high energetic efficiency to be reached are similar, and (ii) the symmetry properties of the kinetic coefficients are different. Based on our results, a strategy for designing efficient Brownian motors is suggested.

Quantifying the interfractional displacement of the gastroesophageal junction during radiation therapy for esophageal cancer

PURPOSE

Accounting for interfractional changes in tumor location improves the accuracy of radiation treatment delivery. The purpose of this study was to quantify the interfractional displacement of the gastroesophageal junction (GEJ) based on standard treatment setup in patients with esophageal cancer undergoing radiation therapy.

METHODS AND MATERIALS

Free-breathing four-dimensional computed tomography (4D-CT) datasets were acquired weekly from 22 patients during treatment for esophageal adenocarcinoma. Scans were registered to baseline (simulation) 4D-CT scans by using bony landmarks. The distance between the center of the GEJ contour on the simulation scan and the mean location of GEJ centers on subsequent scans was used to assess changes in GEJ location between fractions; displacement was also correlated with clinical and respiratory variables.

RESULTS

The mean absolute random error was 1.69 mm (range, 0.11-4.11 mm) in the lateral direction, 1.87 mm (range, 0.51-4.09 mm) in the anterior-posterior (AP) direction, and 3.09 mm (range, 0.99-6.16 mm) in the superior-inferior (SI) direction. The mean absolute systemic GEJ displacement between fractions was 2.88 mm lateral (≥ 5 mm in 14%), mostly leftward; 2.90 mm (≥ 5 mm in 14%) AP, mostly anterior; and 6.77 mm (≥ 1 cm in 18%) SI, mostly inferior. Variations in tidal volume and diaphragmatic excursion during treatment correlated strongly with systematic SI GEJ displacement (r = 0.964, p < 0.0001; and r = 0.944, p < 0.0001, respectively) and moderately with systematic AP GEJ displacement (r = 0.678, p = 0.0005; r = 0.758, p < 0.0001, respectively). Systematic displacement in the inferior direction resulted in higher-than-intended doses (≥ 60 Gy) to the GEJ, with increased hot-spot to the adjacent stomach and lung base.

CONCLUSION

We found large (>1-cm) interfractional displacements in the GEJ in the SI (especially inferior) direction that was not accounted for when skeletal alignment alone was used for patient positioning. Because systematic displacement in the SI direction had dosimetric impact and correlated with tidal volume, better accounting for depth of breathing is needed to reduce interfractional variability.

Accelerated hypofractionated radiation therapy compared to conventionally fractionated radiation therapy for the treatment of inoperable non-small cell lung cancer

Background

While conventionally fractionated radiation therapy alone is an acceptable option for poor prognostic patients with unresectable stage III NSCLC, we hypothesized that accelerated hypofractionated radiotherapy will have similar efficacy without increasing toxicity.

Methods

This is a retrospective analysis of 300 patients diagnosed with stage III NSCLC treated between 1993 and 2009. Patients included in the study were medically or surgically inoperable, were free of metastatic disease at initial workup and did not receive concurrent chemotherapy. Patients were categorized into three groups. Group 1 received 45 Gy in 15 fractions over 3 weeks (Accelerated Radiotherapy (ACRT)) while group 2 received 60-63 Gy (Standard Radiation Therapy 1 (STRT1)) and group 3 received > 63 Gy (Standard Radiation Therapy (STRT2)).

Results

There were 119 (39.7%) patients in the ACRT group, 90 (30.0%) in STRT1 and 91 (30.3%) in STRT2. More patients in the ACRT group had KPS ≤ 60 (p < 0.001), more commonly presented with weight loss > 5% (p = 0.002), and had stage 3B disease (p < 0.001). After adjusting for clinical variables, there were no differences in the radiation groups in terms of the patterns of local or distant tumor control or overall survival. Some benefit in relapse free survival was seen in the STRT1 group as compared to ACRT (HR = 0.65, p = 0.011). Acute toxicity profiles in the ACRT were significantly lower for grade ≥ 2 radiation dermatitis (p = 0.002), nausea/vomiting (p = 0.022), and weight loss during treatment (p = 0.020).

Conclusions

Despite the limitations of a retrospective analysis, our experience of accelerated hypofractionated radiation therapy with 45 Gy in 15 fractions appears to be an acceptable treatment option for poor performance status patients with stage III inoperable tumors. Such a treatment regimen (or higher doses in 15 fractions) should be prospectively evaluated using modern radiation technologies with the addition of sequential high dose chemotherapy in stage III NSCLC.

Dosimetric effects of jaw tracking in step-and-shoot intensity-modulated radiation therapy

The purpose of this work was to determine the dosimetric benefit to normal tissues by tracking the multi‐leaf collimator (MLC) apertures with the photon jaws in step‐and‐shoot intensity‐modulated radiation therapy (IMRT) on the Varian 2100 platform. Radiation treatment plans for ten thoracic, three pediatric, and three head and neck cancer patients were converted to plans with the jaws tracking each segment's MLC apertures, and compared to the original plans in a commercial radiation treatment planning system (TPS). The change in normal tissue dose was evaluated in the new plan by using the parameters V5, V10, and V20 (volumes receiving 5, 10 and 20 Gy, respectively) in the cumulative dose‐volume histogram for the following structures: total lung minus gross target volume, heart, esophagus, spinal cord, liver, parotids, and brainstem. To validate the accuracy of our beam model, MLC transmission was measured and compared to that predicted by the TPS. The greatest changes between the original and new plans occurred at lower dose levels. In all patients, the reduction in V20 was never more than 6.3% and was typically less than 1%; the maximum reduction in V5 was 16.7% and was typically less than 3%. The variation in normal tissue dose reduction was not predictable, and we found no clear parameters that indicated which patients would benefit most from jaw tracking. Our TPS model of MLC transmission agreed with measurements with absolute transmission differences of less than 0.1% and, thus, uncertainties in the model did not contribute significantly to the uncertainty in the dose determination. We conclude that the amount of dose reduction achieved by collimating the jaws around each MLC aperture in step‐and‐shoot IMRT is probably not clinically significant.

PACS numbers: 87.55.D‐ 87.55.de 87.55.dk

Outcome of trimodality-eligible esophagogastric cancer (EC) patients who declined surgery after preoperative chemoradiation

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Background: Patients with localized EC eligible for resection at presentation should receive trimodality therapy (chemoradiation and surgery). However, surgical resection is not always performed in these patients because of poor performance status or reluctance in eligible patients to proceed with surgical resection after preoperative chemoradiation. Reports on the outcome of such patients are rare.

Methods: Between 2002 and 2010, we identified 599 trimodality-eligible EC patients in our prospective database. All patients had extensive baseline staging, preoperative chemoradiation, and preoperative staging that included endoscopic biopsy and PET-CT. Of 599 patients, 32 patients declined surgery.

Results: The median age was 70 years (range, 55-81), 29 patients (90.6%) were men and 30 (93.8%) were Caucasian. Majority had baseline stage II (44%) or III (38%) cancer. All 32 patients had an adenocarcinoma (moderate: 53.1%, poorly: 46.9%) and reached a clinical complete response (negative biopsy and PET in the physiologic range) post-chemoradiation. Four patients had salvage surgery and 3 are alive. Overall, 22 patients remain alive at a median follow up of 33.1 months (95% CI, 28.1-38.1). 3-year overall survival (OS) and relapse-free survival (RFS) were 65.1±10.4% and 37.5±10.3%. Median OS and RFS were 54.2 months (95% CI, 25.7-82.7), 30.4 months (95% CI, 16.3-44.5).

Conclusions: Although the outcome of patients with EC who decline surgical resection after chemoradiation is reasonable, the lack of a validated approach to esophageal preservation dictates that trimodality therapy remains the standard of care in patients with potentially resectable EC.

Development of DRAGON electron cyclotron resonance ion source at Institute of Modern Physics

A new room temperature electron cyclotron resonance (ECR) ion source, DRAGON, is under construction at IMP. DRAGON is designed to operate at microwaves of frequencies of 14.5-18 GHz. Its axial solenoid coils are cooled with evaporative medium to provide an axial magnetic mirror field of 2.5 T at the injection and 1.4 T at the extraction, respectively. In comparison to other conventional room temperature ECR ion sources, DRAGON has so far the largest bore plasma chamber of inner diameter of 126 mm with maximum radial fields of 1.4-1.5 T produced by a non-Halbach permanent sextupole magnet.

Propensity score–based comparison of outcomes with 3D conformal radiotherapy (3D-CRT) versus intensity-modulated radiation therapy (IMRT) in treatment of esophageal cancer

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Background: Although 3D-CRT is the current standard for treatment of esophageal cancers, IMRT improves dose conformality and reduces radiation exposure to normal tissue. There is no assessment of long term clinical outcomes comparing these two modalities.

Methods: Between 1998-2008, 676 patients (3D-CRT=413, IMRT=263) with stage Ib-IVa (AJCC 2002 edition) esophageal cancers were treated with chemoradiation with or without surgery. To correct for potential bias inherent in observational studies, we employed inverse probability of treatment weighted (IPW) methods based on propensity scores. IPW survival plots and IPW log rank tests were used to adjust for potential bias in treatment selection. Treatment probabilities (propensity scores) were estimated using logistic regression.

Results: IMRT patients were less likely to receive induction chemotherapy (35.7% vs 46.7%, p<0.01) and had poorer performance status (KPS≤80: 66.5% vs 50.0%, p<0.01). A fitted multivariate IPW-adjusted Cox model showed that overall survival was significantly associated with age (HR 1.10 for 10 years older, p=0.02), KPS (≤70 vs 90-100, HR 1.5, p=0.0002), having surgery (HR 0.56, p<0.0001), lower vs upper esophagus (HR 1.4, p=0.009), stage (3-4a vs 1-2, HR 2.6, p<0.01), and radiation modality (IMRT vs 3D-CRT, HR 0.68, p<0.0001). 3D-CRT patients had a greater risk of dying at 5 years compared to IMRT (72.6% vs 52.9%, p<0.0001) without a difference in cancer-specific mortality (Gray’s test p=0.86), time to local recurrence (p=0.27) or distant metastasis (p=0.13). Cumulative incidence of documented cardiac deaths trended higher in the 3D-CRT group (p=0.16), but most deaths were due to unknown causes (5 year estimate: 13.4% in 3D-CRT vs 4.2% in IMRT, Gray’s test p<0.0001). Analyses using propensity score as a covariate gave very similar results.

Conclusions: There was a substantially higher risk of non-cancer related deaths in 3D-CRT versus IMRT. While the true cause of death cannot be determined for many 3D-CRT patients, our results suggest that improvements in radiation technology may improve treatment-related mortality in management of esophageal cancer.

Effect of technologic advancements in radiotherapy on postoperative pulmonary complications after neoadjuvant chemoradiation in esophageal cancer

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Background: Although 3D conformal radiation therapy (3D-CRT) is currently the de facto standard for the treatment of esophageal cancers, technologies such as Intensity Modulated Radiation Therapy (IMRT) or Proton Beam Therapy (PBT) are increasingly being used, but the evidence for the clinical benefits of these technologies are lacking. We hypothesized that radiation technology influences perioperative complications in esophageal cancer patients treated with neoadjuvant chemoradiation.

Methods: We evaluated 423 patients (3D-CRT (n=208, 1998-2008), IMRT (n=165, 2004-2011), and PBT (n=50, 2006-2011)) treated with surgical resection after chemoradiation from 1998-2011 at M. D. Anderson Cancer Center. Postoperative complications (Pulmonary, GI, cardiac, wound healing) were recorded up to 30 days postoperatively. Kruskal-Wallis tests and Chi-square or Fisher’s exact tests assessed associations between continuous and categorical variables and the radiation technology, respectively. Logistic regression model tested the association between treatment technologies and complications adjusting for other significant patient characteristics.

Results: While radiation modality was not significantly associated with postoperative GI (leak, ileus, fistula), cardiac (MI, AF, CHF), and wound complications, there was a significant reduction in postoperative pulmonary complications (ARDS, pleural effusion, respiratory insufficiency, pneumonia) for IMRT compared to 3D-CRT (OR 0.46, 95%CI 0.25, 0.83) and PBT compared to 3D-CRT (OR 0.26, 95%CI 0.09, 0.70), but not when IMRT was compared to PBT (OR 1.74, 95%CI 0.66, 4.61) after adjusting for preRT DLCO level. The median length of hospital stay was also significantly different between treatment modalities (12, 10, and 8 days for 3D-CRT, IMRT, and PBT, respectively, p<0.0001). There was no significant association between treatment year with pulmonary complication rates.

Conclusions: Radiation technologies such as IMRT and PBT reduced postoperative pulmonary complication rates compared to 3D-CRT in esophageal cancer patients. This result needs to be confirmed in larger prospective studies.

Nomograms for prognostication of patients with esophageal and gastroesophageal carcinoma undergoing definitive chemoradiotherapy

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Background: Level-1 evidence for definitive chemoradiotherapy (bimodality therapy or BM therapy) has been established for patients with esophageal and gastroesophageal junction cancers (EGEJC) who otherwise do not qualify for surgery; however, tools to estimate individual patient’s prognosis are unavailable. We used a number of clinical pre-treatment and post-treatment parameters to establish two nomograms (for overall survival [OS] and relapse-free survival [RFS]).

Methods: From 2002 through 2010, 257 consecutive patients with EGJEC who received BM therapy and had pre- and post-treatment positron emission tomography (PET) and post-treatment endoscopic biopsies among other assessments were analyzed from a prospectively maintained database. Standard statistical methods were used to generate the nomograms.

Results: The median follow -up time was 39.2 months (95% confidence interval [CI], 35.7 – 50.1). None of 257 patients underwent surgery. Persistent or recurrent cancer was documented in 187 (72.8%) patients. The estimated median survival duration for all 257 patients was 21.1 months (95% CI, 18.9-27.1) and median RFS duration was 11.6 months (95% CI, 9.43-15.0). The estimated OS and RFS rates at 3 years were 37.3% (95% CI, 31.2%-44.7%) and 25.1% (95% CI, 19.9%-31.6%), respectively. After BM therapy, 155 (60.3%) patients achieved a clinical complete response (cCR). In the multivariate analyses, initial standardized uptake value maximum and cCR were independent prognostic variables for OS (P=0.038, P<0.001). Nomogram concordance indices of 0.70 for OS and 0.77 for RFS were established by 200 bootstrap resampling for each of the two outcomes.

Conclusions: Our data suggest that in patients with EGEJC, pre- and post-treatment clinical parameters contribute to the establishment of OS and RFS prognostic nomograms. Upon validated, these nomograms could prove useful in the clinic to individualize therapy.

Status of the laser ion source at IMP

A laser (Nd:YAG laser, 3 J, 1064 nm, 8-10 ns) ion source has been built and under development at IMP to provide pulsed high-charge-state heavy ion beams to a radio frequency quadrupole (RFQ) for upgrading the IMP accelerators with a new low-energy beam injector. The laser ion source currently operates in a direct plasma injection scheme to inject the high charge state ions produced from a solid target into the RFQ. The maximum power density on the target was about 8.4 × 10(12) W∕cm(2). The preliminary experimental results will be presented and discussed in this paper.

A 2.45 GHz electron cyclotron resonance proton ion source and a dual-lens low energy beam transport

The structure and preliminary commissioning results of a new 2.45 GHz ECR proton ion source and a dual-lens low energy beam transport (LEBT) system are presented in this paper. The main magnetic field of the ion source is provided by a set of permanent magnets with two small electro-solenoid magnets at the injection and the extraction to fine tune the magnetic field for better microwave coupling. A 50 keV pulsed proton beam extracted by a three-electrode mechanism passes through the LEBT system of length of 1183 mm. This LEBT consists of a diagnosis chamber, two Glaser lenses, two steering magnets, and a final beam defining cone. A set of inner permanent magnetic rings is embedded in each of the two Glaser lenses to produce a flatter axial-field to reduce the lens aberrations.

Study of ion beam transport from the SECRAL electron cyclotron resonance ion source at the Institute of Modern Physics

Ion beam transport from the Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou (SECRAL) electron cyclotron resonance ion source was studied at the Institute of Modern Physics during 2010. Particle-in-cell simulations and experimental results have shown that both space charge and magnetic aberrations lead to a larger beam envelope and emittance growth. In the existing SECRAL extraction beam line, it has been shown that raising the solenoid lens magnetic field reduces aberrations in the subsequent dipole and results in lower emittance. Detailed beam emittance measurements are presented in this paper.

Characterization of carbapenem-nonsusceptible Klebsiella pneumoniae bloodstream isolates at a Taiwanese hospital: clinical impacts of lowered breakpoints for carbapenems

This study was conducted in order to characterize carbapenem-nonsusceptible Klebsiella pneumoniae isolates and to evaluate the impacts of recently lowered interpretative breakpoints for carbapenems for Enterobacteriaceae. Among 152 K. pneumoniae bloodstream isolates suspected as AmpC or extended-spectrum β-lactamase (ESBL) producers, 58 (38.2%) isolates were currently interpreted as nonsusceptible to ertapenem, imipenem, or meropenem, and 42 (72.4%) of them were categorized as carbapenem-susceptible by the previous criteria. The high revision rate was associated with the predominance (79.3%) of DHA-1 among the carbapenem-nonsusceptible isolates due to both polyclonal and clonal spread. ESBLs were common (~57%) in both ertapenem-susceptible and -nonsusceptible isolates; however, 84.8% of the carbapenem-nonsusceptible isolates were also AmpC producers. The IMP-8 metallo-β-lactamase was detected in three isolates. Polyacrylamide gel electrophoresis suggested decreased OmpK35 expression in all but one ertapenem-nonsusceptible isolate, and genetic disruptions of ompK35 and ompK36 were detected in 30 and six ertapenem-nonsusceptible isolates, respectively. A comparison between patients infected by AmpC- or ESBL-producing ertapenem-susceptible (n=62) isolates and those with isolates revised as ertapenem-nonsusceptible (n=41) revealed more cases of malignancies (36.6% versus 14.5%; p=0.01) and higher Charlson score (p=0.033) among the patients with ertapenem-nonsusceptible isolates; however, the acquisition of an isolate revised as carbapenem-nonsusceptible was not identified as an independent mortality risk factor.

Patients with high body mass index tend to have lower stage of esophageal carcinoma at diagnosis

High body mass index (H-BMI; ≥25 kg/m(2) ) is common in US adults. In a small cohort of esophageal cancer (EC) patients treated with surgery, H-BMI and diagnosis of early stage EC appeared associated. We evaluated a much larger cohort of EC patients. From a prospectively maintained database, we analyzed 925 EC patients who had surgery with or without adjunctive therapy. Various statistical methods were used. Among 925 patients, 69% had H-BMI, and 31% had normal body mass index (<25 kg/m(2) ; N-BMI). H-BMI was associated with men (P<0.001), Caucasians (P=0.064; trend), lower esophageal localization (P<0.001), adenocarcinoma histology (P<0.001), low baseline cT-stage (P=0.003), low baseline overall clinical stage (P=0.003), coronary artery disease (P=0.036), and diabetes (P<0.001). N-BMI was associated with weight loss (P<0.001), alcohol abuse (P=0.056; trend), ever/current smoking (P=0.014), and baseline cN+ (P=0.018). H-BMI patients with cT1 tumors (n=110) had significantly higher rates of gastresophageal reflux disease symptoms (P<0.001), gastresophageal reflux disease history (P<0.001), and Barrett's esophagus history (P<0.001) compared with H-BMI patients with cT2 tumors (n=114). Median survival of N-BMI patients was 36.66 months compared with 53.20 months for H-BMI patients (P=0.005). In multivariate analysis, older age (P<0.001), squamous histology (P=0.002), smoking (P=0.040), weight loss (P=0.002), high baseline stage (P<0.001), high number of ypN+ (P=0.005), high surgical stage (P<0.001), and American Society of Anesthesia scores, three out of four (P<0.001) were independent prognosticators for poor overall survival. We were able to perform propensity-based analysis of surgical complications between H-BMI and N-BMI patients. A comparison of fully matched 376 patients (188 with H-BMI and 188 with N-BMI) found no significant differences in the rate of complications between the two groups. This larger data set confirms that a fraction of H-BMI patients with antecedent history is diagnosed with early baseline EC. Upon validation of our data in an independent cohort, refinements in surveillance of symptomatic H-BMI patients are warranted and could be implemented. Our data also suggest that H-BMI patients do not experience higher rate of surgical complications compared with N-BMI patients.

The utility of proton beam therapy with concurrent chemotherapy for the treatment of esophageal cancers

The standard of care for the management of locally advanced esophageal cancers in the United States is chemotherapy combined with radiation, either definitively, or for those who could tolerate surgery, preoperatively before esophagectomy. Although the appropriate radiation dose remains somewhat controversial, the quality of the radiation delivery is critical for the treatment of esophageal cancer since the esophagus is positioned close to vital structures, such as the heart and lung. The volume and relative doses to these normal tissues affect acute and late term complications. Advances in radiation delivery from 2D to 3D conformal radiation therapy, to Intensity Modulated Radiation Therapy (IMRT) or charged particle therapy (carbon ion or proton beam therapy (PBT)), allow incremental improvements in the therapeutic ratio. This could have implications in non-cancer related morbidity for long term survivors. This article reviews the evolution in radiation technologies and the use of PBT with chemotherapy in the management of esophageal cancer.

Status of particle therapy for lung cancer

The current standard treatment for lung cancer, the most common type of cancer worldwide, depends on disease stage. Surgery is the treatment of choice for early-stage tumors, but radiotherapy is a good option for those with early-stage tumors who cannot undergo surgery, and radiotherapy in conjunction with chemotherapy is the standard of care for locally advanced tumors. Although advances in photon (x-ray)-based radiotherapy involving three-dimensional conformal radiotherapy and intensity-modulated radiotherapy allow radiation doses to be escalated beyond the traditional limit of 60 Gy, this dose is not considered to be sufficient for tumor eradication. Moreover, the improvements in local control and survival conferred by concurrent chemotherapy come at the cost of considerable toxicity owing to inadvertent irradiation of surrounding normal tissues, and this toxicity often limits the radiation dose that can be delivered. Unfortunately for patients with locally advanced lung cancer, local control and survival remain poor. Attempts to improve clinical outcomes for patients with lung cancer have led to the use of charged particle therapy in an effort to exploit the physical properties of such particles to escalate the dose to the tumor while simultaneously limiting the dose to nearby structures, thereby enhancing the therapeutic ratio and potentially improving cancer cure rates. This review summarizes the rationale for and challenges associated with the use of charged particles for lung cancer therapy and reviews the clinical experience to date with using protons and carbon ions for early-stage and locally advanced stage non-small cell lung cancer.

Two-state Brownian motor driven by synchronously fluctuating unbiased forces

As a model of the Brownian motor, we consider a particle moving unidirectionally under the action of two synchronously fluctuating unbiased forces, transverse and longitudinal with respect to the particle track. The former force induces track-normal transitions of the particle between the attached and detached states (with and without a periodic potential, respectively), whereas the latter drives track-parallel motion in either state. Analytical expressions of the current and efficiency are derived for different regimes, with due account of the delayed response of the system to force fluctuations. For a sawtooth potential in the attached state, we reveal several motion regimes affording the maximum current or the maximum efficiency. A special emphasis is placed on the possibility of current reversal. As shown, the interplay between two phase-shifted harmonically varied forces as well as inherent and externally induced asymmetry can lead to the emergence of multiple current reversals, thus enabling the flexible controllability of the motion direction.

Infections caused by Gordonia species at a medical centre in Taiwan, 1997 to 2008

The inability of conventional identification systems to accurately identify Gordonia spp. often results in the misdiagnosis of infections by these rare pathogens, which require genomic sequencing for precise identification. In the present study, we describe nine cases of the various types of infection caused by Gordonia spp. From 1997 to 2008, 66 isolates (from 30 patients) initially identified as Rhodoccus spp. by conventional biochemical methods, by the Bacteriology Laboratory of National Taiwan University Hospital, were retrospectively analysed to assess the accuracy of species identification. Fifteen of these isolates (from nine patients) were later found to be Gordonia spp. by two molecular methods: PCR-restriction fragment length polymorphism for heat shock protein gene (hsp65) and the 16S rRNA gene sequencing analysis. Gordonia sputi (n = 8) was the most common species, followed by Gordonia terrae (n = 7). Most of the isolates were isolated from blood (n = 11), followed by soft tissue (n = 2) and eye (n = 2). Five patients presented with bacteraemia and two of these had catheter-related bloodstream infection. Two patients had soft tissue infections and another two patients had infective keratitis and conjunctivitis. The random amplified polymorphic DNA patterns for isolates from different patients were different, indicating that they were genetically unrelated. Accurate identification with molecular methods is required if the role of Gordonia spp. in causing infection is to be recognized.