Two states of magnetotail dipolarization fronts: A statistical study

We study the ion density and temperature in the predipolarization and postdipolarization plasma sheets in the Earth's magnetotail using 9 years (2001-2009) of Cluster data. For our study we selected cases when Cluster observed dipolarization fronts (DFs) with an earthward plasma flow greater than 150km/s. We perform a statistical study of the temperature and density variations during the DF crossings. Earlier studies concluded that on average, the temperature increases while the density decreases across the DF. Our statistical results show a more diverse picture: While ∼54% of the DFs follow this pattern (category A), for ∼28% the temperature decreases while the density increases across the DF (category B). We found an overall decrease in thermal pressure for category A DFs with a more pronounced decrease at the DF duskside, while DFs of category B showed no clear pattern in the pressure change. Both categories are associated with earthward plasma flows but with some difference: (1) category A flows are faster than category B flows, (2) the observations indicate that category B flows are directed perpendicular to the current in the near-Earth current sheet while category A flows are tilted slightly duskward from this direction, and (3) the background Bz of category B is higher than that of category A. Based on these results, we hypothesize that after reconnection takes place, a bursty bulk flow emerges with category A characteristics, and as it travels earthward, it further evolves into category B characteristics, which is in a more dipolarized region with slower plasma flow (closer to the flow-braking region).

Increases in plasma sheet temperature with solar wind driving during substorm growth phases

During substorm growth phases, magnetic reconnection at the magnetopause extracts ∼10¹⁵ J from the solar wind which is then stored in the magnetotail lobes. Plasma sheet pressure increases to balance magnetic flux density increases in the lobes. Here we examine plasma sheet pressure, density, and temperature during substorm growth phases using 9 years of Cluster data (>316,000 data points). We show that plasma sheet pressure and temperature are higher during growth phases with higher solar wind driving, whereas the density is approximately constant. We also show a weak correlation between plasma sheet temperature before onset and the minimum SuperMAG AL (SML) auroral index in the subsequent substorm. We discuss how energization of the plasma sheet before onset may result from thermodynamically adiabatic processes; how hotter plasma sheets may result in magnetotail instabilities, and how this relates to the onset and size of the subsequent substorm expansion phase.

Real-time assessment of relapse risk based on the WT1 marker in acute leukemia and myelodysplastic syndrome patients after hematopoietic cell transplantation

Relapse is the major cause of treatment failure after allogeneic hematopoietic cell transplantation (alloHCT) for acute leukemia and myelodysplastic syndrome (MDS). Wilms' tumor Ag (WT1) is overexpressed in the majority of acute leukemia and MDS patients and has been proposed as a universal diagnostic marker for detection of impending relapse. Comprehensive studies have shown that WT1 transcript levels have predictive value in acute leukemia patients in CR after chemotherapy. However, the focus of this study is the period after alloHCT for predicting relapse onset. We analyzed the accumulation of WT1 mRNA transcripts in PB of 82 leukemia and MDS patients and defined specific molecular ratios for relapse prediction. The extensively validated WT1/c-ABL ratio was used to normalize increases in WT1 transcript levels. The observed lead time of crossing or exceeding set WT1 levels is presented along with linear interpolation to estimate the calculated day the WT1 thresholds were crossed. The WT1/c-ABL transcript ratio of 50 or above yielded 100% specificity and 75% sensitivity reliably predicting future relapse with an observed average of 29.4 days (s.d.=19.8) and a calculated average of 63 days (s.d.=29.3) lead time before morphologic confirmation. A lower ratio of 20 or above gave lower specificity, but higher sensitivity (84.8% and 87.5%, respectively) identified more patients who relapsed, at earlier times, providing an earlier warning with actual average lead time of 49.1 days (s.d.=30.8) and calculated average of 78 days (s.d.=28.8). WT1 transcript levels serve as a diagnostic relapse test with greater sensitivity than the morphologic approach used in the clinic as a readout.

Abstract P2-02-09: Accuracy of MRI for estimating residual tumor size after neoadjuvant endocrine therapy in early stage breast cancer with ER positive and HER2 negative

Back ground

Neoadjuvant endocrine therapy (NET) is increasingly being used in the management of breast cancer patients with ER positive and HER2 negative. A major clinical benefit is that patients with large operable tumors may be offered breast-conserving surgery (BCS). Therefore, success of BCS following NAT depends on accurate assessment of the residual tumor extent after NAT. The correlation between the extent of the tumor at pathology and preoperative assessments of the size obtained by physical examination and conventional imaging is impaired by hormonal therapy-induced necrosis and fibrosis. However, the most superior method to assess the extent of residual disease after NAT was unknown. The aim of this study was to evaluate the relative accuracies of mammography(MMG), ultrasound(US), specimen mammography(SMMG) and MRI in predicting residual tumor size and pathological response after neoadjuvant endocrine therapy (NET) in patients with ER positive and HER2 negative. Each prediction method (EPM) was compared with the gold standard of surgical pathology.

Patients and methods

From April 2010 to December 2012, 50 post menopausal patients with breast cancer at clinical stages T1c-T2N0 were prospectively enrolled in this study on NET. Fifty patients (age range, 52-75 years; mean age, 64.1 years) who received NET with 24 weeks of letrozole were evaluated with EPM before and after NET.

We compared the predicted residual tumor size and the predicted response on imaging with residual tumor size and response on the pathologically determined size. We defined the tumor sizes measured by EPM and pathology as in agreement when the greatest tumor dimension measured by EPM was within 70_120% of the measurement determined by microscopic pathology. The EPM assessment was categorized as an underestimation when the longest diameter on imaging was <70% that at pathology and as an overestimation when the longest diameter on imaging was>120% that at pathology. Statistical analysis was performed using logistic regression analysis.

Results

The correlation coefficient between the residual tumor sizes determined by pathology and the predicted tumor size was 0.721(p = 0.651) for MMG, -0.111(p = 0.642) for US, 0.723(P = 0.001) for SMMG and 0.714 (p<0.000001) for MRI.

The rate of agreement between the final response predictions and the responses measured by pathology were 50% for MMG, 40% for US, 35% for SMMG and 78% for MRI. The MMG,US, SMMG and MRI measurement disagreed with the pathologically determined size in 50%,60%,65%,22%, overestimating the size in 0%,12%, 11%,2% and underestimating the size in 50%, 48%,53%,20% respectively.

Conclusions

Predictions of response and residual tumor size made on MRI were best correlated with the assessments of response and residual tumor size made on pathology than were predictions made on the basis of clinical examination, mammography or ultrasound. MRI is one of the most accurate methods for predicting the extent of residual tumor after NET.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-02-09.

Clinical significance of plasma fibrinogen level as a predictive marker for postoperative recurrence of esophageal squamous cell carcinoma in patients receiving neoadjuvant treatment

Among multidisciplinary therapies developed for advanced esophageal cancer, neoadjuvant chemotherapy and chemoradiotherapy have been established as standard treatments. To deliver cautious follow up and intense treatment for high-risk patients, a simple and instructive biomarker for the postoperative recurrence needs to be identified. Fibrinogen, a common component of hemostasis, has been suggested to not only play an important role in cancer metastasis, but also correlate with tumor recurrence. We aim to clarify the validity of plasma fibrinogen as a marker for predicting the postoperative recurrence of esophageal squamous cell carcinoma patients who received neoadjuvant treatment. We reviewed 72 consecutive patients with esophageal squamous cell carcinoma who received neoadjuvant chemotherapy or chemoradiotherapy, followed by esophagectomy at the Keio University Hospital from 2001 to 2010. Of them, we retrospectively examined 68 patients who underwent plasma fibrinogen examination before and after neoadjuvant treatment and underwent transthoracic radical esophagectomy. We investigated patient characteristics, clinicopathological factors, neoadjuvant treatment effects, postoperative course, and plasma fibrinogen levels. We investigated pretreatment and preoperative (postneoadjuvant treatment) plasma fibrinogen levels, as well as changes in fibrinogen levels before and after neoadjuvant treatment. Patients with preoperative hyperfibrinogenemia (>350 mg/dL) and patients with increased plasma fibrinogen levels during neoadjuvant treatment showed significantly shorter postoperative disease-free survival (DFS) (P = 0.002 and P = 0.037, respectively). Moreover, we classified these patients into three classes on the basis of their preoperative fibrinogen levels and changes in fibrinogen levels during neoadjuvant treatment. Patients who had both high preoperative plasma fibrinogen and increased fibrinogen levels showed significantly shorter DFS than others. In contrast, patients who had normal preoperative plasma fibrinogen and decreased fibrinogen levels showed significantly longer DFS. Based on this fibrinogen classification, we could differentiate between significantly favorable and poor prognosis patients group. Overall, this classification (hazard ratio = 1.812, P = 0.013) and the response to neoadjuvant treatment (hazard ratio = 0.350, P = 0.007) were found to be significant determining factors for postoperative DFS. With the validity of preoperative plasma fibrinogen levels and changes in fibrinogen levels during neoadjuvant treatment, the plasma fibrinogen level was found to be a possible biomarker for postoperative recurrence in advanced esophageal cancer patients who received neoadjuvant treatment. Moreover, plasma fibrinogen classification could be a simple and valuable predictive marker for postoperative follow up.

Clinical utility of preoperative evaluation of bronchial arteries by three-dimensional computed tomographic angiography for esophageal cancer surgery

An identification of bronchial arteries (BAs) is critical in esophageal cancer surgery to avoid tracheobronchial ischemia and unexpected massive bleeding during surgical procedure particularly in thoracoscopic video-assisted esophagectomy. We describe the efficacy of three-dimensional computed tomographic angiography (3D-CTA) of BAs for preoperative evaluation in esophageal cancer surgery. Sixty-four patients with esophageal cancer who preoperatively underwent multidetector computed tomography examination were included in this study. We evaluated the number, origin, and intraoperative preservation rate of BAs, and we compared the number of thoracic paratracheal lymph nodes harvested between two groups comprising patients who either underwent preoperative 3D-CTA of BAs (3D-CTA group) or did not (non-3D-CTA group). The right and left BAs were preoperatively identified in 62 patients (97%) and 55 patients (86%), respectively, using 3D-CTA. In 34 patients (53%), the right BA originated as a common trunk with the right intercostal artery. In 48 patients (75%), the left BA originated from the descending aorta as a single or double branch. Some anomalies such as the right BA originated from the left subclavian artery were observed. In all patients, either the right or the left BA was preserved. The number of harvested lymph nodes in left side of paratrachea was significantly increased in 3D-CTA group, than those in non-3D-CTA group. 3D-CTA clearly revealed BA anatomy, contributing to BA preservation and safe and precise lymphadenectomy in esophageal cancer surgery. 3D-CTA of BAs is useful for preoperative evaluation in esophageal cancer surgery.