The role of sequential 18(F) -FDG PET/CT in predicting tumour response after preoperative chemoradiation for rectal cancer

AIM

The aim of this study was to investigate the potential of sequential positron emission tomography (PET)/CT standardized uptake value (SUV)/metabolic area variation in predicting the pathological response to preoperative chemoradiotherapy (CRT) for rectal cancer.

METHOD

Fifty-three patients diagnosed with clinical T3-4 and/or N+ rectal cancer were enrolled. All patients received CRT followed by radical surgery after 6-8 weeks. A PET/CT scan was performed before (PET/CT1) initiation of treatment and a second scan (PET/CT2) was performed within 1 week after the completion of CRT. Thirty-five of 53 patients also underwent a third (PET/CT3) scan within 1 week before surgery. Maximal SUV within the tumour (SUVmax), average SUV within the tumour (SUVmean), metabolic tumour volume (MV), total lesion glycolysis (TLG) and response indices (∆%, i.e. the percentage difference between two different PET/CT scans for SUVmax, SUVmean, MV and TLG) were calculated. The different metabolic parameters were analysed and correlated with the tumour regression grade (TRG) score.

RESULTS

When patients were regrouped as responders (TRG 3-4) and nonresponders (TRG 0-2), significant differences were observed in the percentage differences between PET/CT1 and PET/CT3 for MV (∆%MV(1-3); 91.08% vs 75.43%) and for TLG (∆%TLG(1-3); 94.00% vs 82.02%). As demonstrated by receiver-operating characteristics analysis, ∆%MV(1-3) and ∆%TLG(1-3) both had a strong capability to discriminate between responders and nonresponders. Patients classified as having a pathological complete response (pCR) and a non-pCR showed significant differences in the percentage difference between PET/CT1 and PET/CT3 in SUVmax (∆% SUVmax(1-3); 69.17% vs 57.77%), SUVmean (∆% SUVmean(1-3); 44.20% vs 30.19%), ∆%MV(1-3) (90.93% vs 80.30%) and ∆%TLG(1-3) (94.22% vs 85.63%). ∆%TLG (1-3) was a more powerful discriminator than the others.

CONCLUSION

Differences in the SUV/metabolic area with 18F-fluorodeoxyglucose (18(F) -FDG) PET/CT have the potential to predict a response to preoperative CRT for rectal cancer.

A phase II evaluation of motesanib (AMG 706) in the treatment of persistent or recurrent ovarian, fallopian tube and primary peritoneal carcinomas: a Gynecologic Oncology Group study

OBJECTIVES

Vascular endothelial growth factors (VEGF) and their receptors have a critical role in stimulating the growth of ovarian cancer cells. Motesanib is a small molecule inhibitor of multiple receptor tyrosine kinases including VEGF receptors 1-3, as well as c-KIT and platelet-derived growth factor which are related to the VEGF family.

PATIENTS AND METHODS

Twenty-two eligible patients with recurrent ovarian, fallopian tube or primary peritoneal carcinoma were treated with an oral daily dose of 125 mg of motesanib. Peripheral blood was analyzed for circulating tumor cells (CTC) and circulating endothelial cells/circulating endothelial progenitors (CEC/CEP), VEGF levels and cell-free circulating DNA (cfDNA).

RESULTS

The study was abruptly halted after four patients developed posterior reversible encephalopathy syndrome. One patient had a partial response and seven patients had stable disease at the time they were removed from study treatment. Twelve of the 22 patients (50%) had indeterminate responses at trial closure. Early closure without clinical efficacy data precludes meaningful correlative studies.

CONCLUSIONS

The serious central nervous system toxicity observed in patients with recurrent ovarian cancer precluded full examination of this agent in this population. There were no clear cut explanations for the high incidence of this known class effect in the study population compared with patients with other cancers.

The p53-Bak apoptotic signaling axis plays an essential role in regulating differentiation of the ocular lens

The tumor suppressor p53 is a master regulator of apoptosis and also plays a key role in cell cycle checking. In our previous studies, we demonstrated that p53 directly regulates Bak in mouse JB6 cells (Qin et al. 2008. Cancer Research. 68(11):4150) and that p53-Bak signaling axis plays an important role in mediating EGCG-induced apoptosis. Here, we demonstrate that the same p53-Bak apoptotic signaling axis executes an essential role in regulating lens cell differentiation. First, during mouse lens development, p53 is expressed and differentially phosphorylated at different residues. Associated with p53 expression, Bak is also significantly expressed during mouse lens development. Second, human p53 directly regulates Bak promoter and Bak expression in p53 knockout mice (p53-/-) was significantly downregulated. Third, during in vitro bFGF-induced lens cell differentiation, knockdown of p53 or Bak leads to significant inhibition of lens cell differentiation. Fourth, besides the major distribution of Bak in cytoplasm, it is also localized in the nucleus in normal lens or bFGF-induced differentiating lens cells. Finally, p53 and Bak are co-localized in both cytoplasm and nucleus, and their interaction regulates the stability of p53. Together, these results demonstrate for the first time that the p53-Bak apoptotic signaling axis plays an essential role in regulating lens differentiation.

bcl-2 plays a major role in resistance to dexamethasone induced apoptosis in multiple myeloma cell lines

The role of bcl-2 in protection against apoptosis is well established in a great variety of cells and has become a hallmark of drug-resistance in many tumor cell lines, notably in lymphomas and leukemias. However, the role of bcl-2 in spontaneous and drug induced apoptosis in multiple myeloma (MM), is not yet established, particularly since the frequency of t(14:18) in MM is relatively low. We have recently studied the steady-state levels of mRNA transcripts for bcl-2, bar and P53 in 8 MM cell lines and found inverse correlation between the levels of bcl-2 mRNA transcripts and sensitivity to dexamethasone (DEX) induced apoptosis. Moreover, we have also shown that mRNA transcripts for bcl-2 were further down-regulated in 2 DEX sensitive cell lines in the course of DEX induced apoptosis, whereas mRNA transcripts for bcl-2 were unchanged in 2 DEX-resistant MM cell lines (Int J Oncol 8: 719-726, 1996). In this study, we determined the steady-state levels of bcl-2, P53 and bar proteins in 4 myeloma cell lines, and the levels were correlated with sensitivity to DEX induced apoptosis. Two cell lines (HS-Sultan and ARH-77) expressed relatively high levels of bcl-2 protein and were highly resistant to DEX induced apoptosis. Two cell lines (8226 and ARP-1) expressed relatively low levels of bcl-2 protein, and were 2-3 logs more sensitive to DEX. In contrast, the levels of bar protein were similar in all cell lines tested. The steady-state levels of P53 protein varied among the various cell lines but did not correlate with resistance to DEX. Induction of apoptosis in the DEX sensitive cells resulted in an early down-regulation of bcl-2 and P53 protein, whereas the levels of bar protein were only slightly decreased. In contrast to the DEX sensitive cell lines, the levels of bcl-2, bar and P53 proteins in the DEX resistant cell lines were unchanged during 72 h of treatment with DEX. Thus, the changes in the protein levels are in good agreement with the changes reported earlier for mRNA transcript of these oncogenes.

Genome-wide association study validation identifies novel loci for atherosclerotic cardiovascular disease

BACKGROUND

Genetic variants influencing lipid levels and risk of coronary artery disease (CAD) have been identified by recent genome-wide association studies (GWAS).

OBJECTIVES

To test the association of single nucleotide polymorphisms (SNPs) implicated in lipoprotein metabolism and CAD in GWAS with atherosclerotic cardiovascular disease (ASCVD, including ischemic stroke [IS] and myocardial infarction [MI] phenotypes).

PATIENTS AND METHODS

A two-stage genetic association study was conducted in the Chinese Hans population. Stage I included a cohort with 451 IS cases and 462 controls for association analysis using 92 SNPs. Stage II examined the associations of eight positive variants and five additional variants with IS, MI and ASCVD in a cohort with 779 IS cases and 836 controls and a cohort with 824 MI cases and 737 controls.

RESULTS

The T allele of rs4731702 located near the KLF14 gene was associated with a decreased risk of MI with an odds ratio (OR) of 0.72 (P<3.85×10(-3)). The rs4731702-T allele was also associated with a decreased risk of ASCVD with an OR of 0.78 (Pmeta-analysis<5.43×10(-4)). In addition, we found that a missense variant of KLF14, rs111400400 (Ser58Pro), was associated with MI.

CONCLUSION

Genetic variants newly identified near/in the KLF14 gene were implicated in the aetiology of atherosclerotic-related phenotypes.

SU-E-J-131: Implement a Passive Breath Gating Equipment for Gated CBCT Imaging: A Feasibility Study

PURPOSE

To investigate the feasibility of using a patient passive breath gating (PBG) equipment in kilo-voltage cone-beam CT (kVCBCT) image acquisition to reduce the respiratory induced motion artifacts for image-guided radiotherapy.

METHODS

A PBG equipment developed in our department was used to passively block patient's breathing. Assisted by this device, patients were able to hold their breaths for 15-25 seconds. An infrared block was placed on the patient's body and the breath-hold was triggered by the signal from the Varian RPM system. Three sets of kVCBCT images were acquired using the same imaging parameters with the OBI system on Varian Trilogy for a gastric cancer patient: free breathing (FB), with two-breath-hold (BH1) and three-breath-hold (BH2). Patient was allowed to breathe normally for 5-10s between breath-hold. A planning CT was obtained with one breath-hold on a conventional 4D CT scanner. The diaphragm position on FB, BH1 and BH2 CBCT images was compared with its position on the planning CT to assess the motion artifacts.

RESULTS

The acquisition time for each of the three kVCBCTs was 60 seconds. The patient tolerated the breath-hold CBCT scanning well. Severe image blurriness and streak artifacts caused by respiratory motion were observed near the diaphragm on FB CBCT. However, for the breath-hold CBCT images, the motion artifacts were reduced and the diaphragm edge was restored. Two-breath-hold scan (BH1) produced better image quality than three-breath-hold (BH2). The details of the diaphragm edge on BH1 images were comparable to the planning CT.

CONCLUSIONS

Diaphragm motion causes image distortion in FB CBCT. The PBG can be used in kVCBCT acquisition to reduce motion artifacts. The breath-hold kVCBCT can produce higher image quality for image-guided radiotherapy and adaptive radiotherapy in the thorax and abdominal regions. Conflict of Interest (only if applicable): Research supported by Varian Medical System. This work is partly supported by Varian Medical System.

SU-E-T-154: Online Dose Verification with Gafchromic Film for Fixed-Gantry and Rotational Intensity Modulated Radiation Therapy: A Phantom Study

PURPOSE

The patient specific quality assurance (QA) measurements for fixed-gantry and rotational intensity modulated radiation therapy (IMRT and VMAT/RapidArc) are usually performed on a homogeneous phantom prior to the treatment. The purpose of this study is to develop an online method to verify the delivered dose to the patient on the treatment day.

METHODS

An anthropomorphic (Rando) head phantom was immobilized in treatment position with a thermoplastic mask to simulate a real patient. A sheet of gafchromic film (EBT2) was sandwiched between a 1-cm-thick solid water slab, which was fixed to the Type-S extension board, and the patient's head hold (a pillow used here). The CT images of the Rando phantom were acquired and exported to the treatment planning systems. One step-and-shot fixed-gantry IMRT plan and one RapidArc plan were generated and the dose distributions on the film plane were calculated. The two plans were delivered to the patient (Rando phantom in this study) in the treatment position on a Varian Trilogy linear accelerator with two new films. The films were scanned, and the measurements were compared with the planned doses.

RESULTS

The composite dose distributions measured on the film plane were the actual delivered dose for the treatment. The comparison between the measurement and planned dose profiles shows an agreement within 3% because of the good reproducibility of phantom positioning. Gamma pass rates (using 3mm and 3% criteria) for the IMRT and RapidArc plan were found to be 95% and 94%, respectively.

CONCLUSIONS

The phantom study has demonstrated the feasibility of using gafchromic film for online dose verification. This simple method takes into account the patient heterogeneity and the treatment associated uncertainties such as setup error, intrafraction motions and machine related variations. It can be implemented as an online physics and/or clinical QA tool without taking additional machine time.

Fine structure analysis and sintering properties of Si-doped hydroxyapatite

Si-doped hydroxyapatite (Si-HA) has been intensively investigated as a promising bone biomaterial because of the biomineralization and bone formation benefit from silicon addition. In the current work, Si-HA samples were synthesized by the aqueous precipitation method. The sintering property of Si-HA was studied in terms of phase composition and transition, which was influenced by the Si doping percentage and sintering temperature. The results indicate that all the as-prepared and sintered low Si doping samples (Si% ≤ 1.6 wt%) possess HA phases; while the high Si doping samples (Si% ≥ 2 wt%) present amorphous phases as prepared, and largely or even completely transform to β-tricalcium phosphate (β-TCP) phase after sintering at 1250 °C. The Rietveld refinement on x-ray diffraction patterns was conducted to determine the particle sizes, microstrain factors and anisotropic distributions. According to the refined results, the calculated anisotropic particle sizes correspond to the observations made by transmission electron microscopy. The microstrains also present anisotropic distributions in all refinements. The accurate variation in the fine structure of Si-HA has been studied by the improved refinements after considering the anisotropic distribution.

The Yangtze-Hydro Project: a Chinese-German environmental program

Water of good quality is one of the basic needs of human life. Worldwide, great efforts are being undertaken for an assured water supply. In this respect, one of the largest water technology projects worldwide is the Yangtze Three Gorges Dam in China. There is a need for extensive scientific and technical understanding of the challenges arising from this large hydrological engineering project. German and Chinese groups from various scientific fields are collaborating to provide knowledge for the sustainable management of the reservoir. In this project description, the Yangtze Three Gorges Dam Project, its goals and challenges, are described in brief, and the contributions of the German research projects are presented.