Early prediction of pathological complete response (pCR) of rectal cancer after 1 week of preoperative radiochemotherapy (RCT) using positron emission computererized tomography (PET-CT) imaging

572

Background: Preoperative radiochemotherapy (RCT) is the standard treatment of locally advanced rectal cancer (LARC), obtaining pathological complete response (pCR) in 15%-30% of cases. Post-RCT reduction of 18F-fluorodeoxyglucose (FDG) uptake within the tumor compared with the baseline, i.e. the tumor's metabolic response, correlates with pCR. However, an earlier prediction of pCR could enable tailored modifications of the treatment. We hence evaluated the correlation between the metabolic response after only one week of RCT for LARC and the actual pCR at the post-RCT surgery.

Methods: Patients (pts) were eligible for this prospective study if they had LARC, defined as T3-4NX or TxN+ tumors by pre-treatment PET-CT and endoscopic ultrasound. Pts received standard RCT regimen, consisting of 50.4Gy radiotherapy concurrently with a fluoropyrimidine-based chemotherapy, followed by surgery. Pts underwent baseline FDG-PET-CT imaging within 2 weeks prior to the initiation of RCT and a second one on day 8 of RCT. Maximum standardized uptake value (SUV-max) was measured in both scans and changes in FDG- uptake were recorded. Man-Whitney test was used to evaluate differences in the SUV-max between baseline and day 8 in pts obtaining pCR and those who did not.

Results: Twenty pts participated in the study. Half were males and the median age was 64 years. Ten pts had T3N0 tumors and 10 had T3N+ disease. Radical surgery was done in 19 pts and local excision in one. Considering the entire group, there was a borderline-significant difference between the metabolic response of pts with pCR and those without pCR (Chi-square = 3.429, p = 0.064). Yet, the changes in FGD-uptake were able to identify pts who achieved pCR and those who did not: only pts with a decrease of more than 33% in SUV-max had pCR while none of the pts who had less than 8.9% decrease in SUV-max had pCR.

Conclusions: A decrease in SUV-max between baseline-PET-CT scans and scans done after only one week of RCT for LARC may be able to predict the achievement of pCR in the post-RCT surgical specimen. Validation in a larger independent cohort is planned.

No significant financial relationships to disclose.

The role of postoperative PET-CT in the evaluation of patients with high-risk stage III colorectal cancer (CRC)

566

Background: Routine PET-CT evaluation is still not indicated for stage III CRC patients; however accumulating data suggest that it may modify these patients' staging and treatment. We hence evaluated the role of PET-CT in high risk stage III CRC patients and to characterize positive predictors.

Methods: Retrospective chart review of stage III CRC patients who underwent PET-CT for being at high risk for systemic disease attributable to: early T stage (T < 3), grade > 3, < 12 lymph-nodes examined, > 3 involved lymph-nodes, elevated postoperative CEA and/or CA-19.9. The demographic and clinicopathological characteristics of patients found to have metastatic disease were compared to those who were negative.

Results: Seventy-three patients (33 males [45%], median age 67 years [range: 29-88 years]) were included. Pathologic FDG-uptake was observed in 33 (45%) patients. Of them, 16 (22%) were upstaged with altered treatment protocol, 13 (18%) required further work-up and 4 (5%) were found to have post operative changes. Elevated post-operative CEA and CA-19.9 levels correlated with positive PET-CT (p = 0.002 and p = 0.015, respectively). None of the other examined parameters differed between the groups. With a median follow-up of 26 months (range:1-63 months), overall survival was 88% in patients with positive PET-CT and 92% in patients with negative PET-CT. Eight patients in the positive group were disease free following metastectomy, five were alive with disease, two patients died of disease and one patient died of other cause.

Conclusions: Selective postoperative PET-CT influenced staging/therapy in 22% of high risk stage III CRC patients. Postoperative CEA and CA-19.9 levels may play a role in selecting eligible patients. Failure to identify other parameters may be related to the preexisting selection bias and the small cohort.

No significant financial relationships to disclose.

State-dependent radial elasticity of attached cross-bridges in single skinned fibres of rabbit psoas muscle

1. In a single skinned fibre of rabbit psoas muscle, upon attachment of cross-bridges to actin in the presence of ADP or pyrophosphate (PP(i)), the separation between the contractile filaments, as determined by equatorial X-ray diffraction, is found to decrease, suggesting that force is generated in the radial direction.2. The single muscle fibres were subjected to compression by 0-8% of dextran T(500). The changes in lattice spacings by dextran compression were compared with changes induced by cross-bridge attachment to actin. Based on this comparison, the magnitude and the direction of the radial force generated by the attached cross-bridges were estimated. The radial cross-bridge force varied with filament separation, and the magnitude of the radial cross-bridge force reached as high as the maximal axial force produced during isometric contraction.3. One key parameter of the radial elasticity, i.e. the equilibrium spacing where the radial force is zero, was found to depend on the ligand bound to the myosin head. In the presence of ADP, the equilibrium spacing was 36 nm. In the presence of MgPP(i) the equilibrium spacing shifted to 35 nm and Ca(2+) had little effect on the equilibrium spacing.4. The equilibrium spacing was independent of the fraction of cross-bridges attached to actin. The fraction of cross-bridges attached in rigor was modulated from 100% to close to 0% by adding up to 10 mM of ATPgammaS in the rigor solution. The lattice spacing remained at 38 nm, the equilibrium spacing for nucleotide-free cross-bridges at mu = 170 mM.5. Radial force generated by cross-bridges in rigor at large lattice spacings (38 nm </= d(10) </= 46 nm) appeared to vary linearly with lattice spacing.6. The titration of ATPgammaS to fibres in rigor provided a correlation between the radial stiffness of the nucleotide-free cross-bridges and the equatorial intensities. The relation between the equatorial intensity ratio I(11)/I(10) and radial stiffness appeared to be approximately linear.7. The fibres under different conditions showed a wide range of radial stiffness, which was not proportional to the apparent axial stiffness of the fibre. If the apparent axial stiffness is a measure of the fraction of cross-bridges bound to actin, it follows that the radial elastic constant is state dependent; or vice versa.8. Differences in equilibrium lattice spacing and in radial elastic constant, most probably reflect differences in the molecular structure of the acto-myosin complex and there is more than one single conformation of the various strongly bound cross-bridge states.9. Determining equilibrium spacings of the radial elasticity appears to be an effective new approach in detecting structural differences among the attached cross-bridges, since this approach is independent of the fraction of cross-bridges attached, a factor that frequently encumbers the interpretation of structural studies of attached cross-bridge states.

Hydration does not prevent orthostatic hypercoagulability

Prolonged standing activates the coagulation cascade by the activation of endothelial cells, and probably the haemoconcentration effect contributes to this "orthostatic hypercoagulability". It was the objective of this study to assess whether rehydration (haemodilution) prevents or attenuates orthostatic induced thrombin formation. Twelve healthy young subjects were studied during two separate visits. Haematocrit (Hct), total plasma protein, coagulation profile tests, including endothelial activation related factors, and protein C global pathway were studied at rest supine, and while standing at 15 and 30 minutes (min). During the second visit the study was repeated after intravenous 1.5 liter 0.9% saline. While in supine posture, intravenous rehydration resulted in Hct reduction of 14.2 +/- 2% (haemodilution), a decrease of 11.5 +/- 1.3% in total protein, as well as a significant dilutional effect on most of the coagulation parameters. Still standing for 30 min, with and without rehydration caused a comparable increase in tissue factor by 49.83 +/- 13.6%, and 35.34 +/- 8.55% (p>0.05), respectively and in von Willebrand factor (vWF) 9.5 +/- 2.4% and 13.59 +/- 2.17% (p>0.05), respectively. At 30 min standing, after intravenous rehydration, factor V and VIII activities, and fibrinogen rose by 22 +/- 1.9%, 31.2 +/- 6.2%, 9.15 +/- 2.64%, (p<0.002 for all), respectively. Prothrombin fragments 1+2 elevated by 84.84 +/- 15.3% (p<0.001). Comparable results were obtained with and without the rehydration. Additionally, protein C assay results decreased by 19.4 +/-1.7% and 17.5 +/- 2.6%, with and without fluids (p<0.05 for both). In healthy subjects, intravenous prophylactic rehydration with normal saline resulted in a haemodilution of all the coagulation parameters, but did neither attenuate nor prevent the orthostatic hypercoagulability.

Psychological distress among male patients and male spouses: what do oncologists need to know?

BACKGROUND

The aim of the current study was to strengthen the knowledge of oncologists concerning psychological distress and social support among married and unmarried male cancer patients and healthy male spouses of female cancer patients.

PATIENTS AND METHODS

Three groups of men were recruited from three major cancer centers in Israel: 185 married colon and rectal cancer patients, 54 single (unmarried) colon and rectal cancer patients, and 153 male spouses of female cancer patients. Participants were evaluated on four standardized instruments measuring psychological distress, coping, and social support.

RESULTS

About 42.6% of the participants reported on a clinical level of psychological distress, with the highest rates (61.1%) among the single (unmarried) patients. Distress was negatively correlated to Karnofsky score and coping variables among all study groups. Distress was significantly and negatively correlated to social support variables among the spouses and married patients but not among the single patient groups.

CONCLUSIONS

Social support received by male cancer patients from friends and family may be mediated by spouse support. As a result, single male patients are at higher risk for psychological distress. Male spouses were also found to have high rates of distress. These two groups need special attention by oncologists.

Circulating microRNAs as potential blood-based biomarkers for detection of colorectal cancer

e15040

Background: Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide. While there is a strong correlation between stage and prognosis in this disease, current screening methods for CRC have significant limitations, and newer technological approaches are desired. Circulating nucleic acids in body fluids have been studied as a source for diagnostic information and for cancer screening, yet the potential of microRNAs, a family of small non-coding regulatory RNAs, has not yet been thoroughly explored. Here we investigated the utility of microRNAs as potential serum biomarkers for early detection of CRC. Methods: We developed protocols for extracting and quantifying microRNA levels in serum. Serum levels of more than 350 microRNAs were measured using qRT-PCR on samples from 10 healthy controls and 10 CRC patients. Most microRNAs showed consistent levels across different individuals. A subset of microRNAs had significant differences in abundance between the two groups and was studied on a larger cohort of 118 patients and controls. Results: We initially identified a subset of microRNAs that showed significant differential abundance between sera of CRC patients and controls. Measuring the serum levels of 22 microRNAs on a cohort of 118 patients and controls, we showed that levels of circulating microRNAs can be very informative in the identification of CRC. Conclusions: The results demonstrate the potential of the microRNA processing and analysis methods that we developed. Certain microRNAs were found in different amounts in sera of CRC patients compared to healthy controls. Thus, circulating microRNAs represent promising candidates for diagnostic biomarkers in CRC.

[Table: see text]

Force-generating cross-bridges during ramp-shaped releases: evidence for a new structural state

Mechanical and two-dimensional (2D) x-ray diffraction studies suggest that during isometric steady-state contraction, strongly bound cross-bridges mostly occupy early states in the power stroke, whereas rigor or rigor-like cross-bridges could not be detected. However, it remained unclear whether cross-bridges accumulate, at least transiently, in rigor or rigor-like states in response to rapid-length releases. We addressed this question using time-resolved recording of 2D x-ray diffraction patterns of permeabilized fibers from rabbit psoas muscles during isometric contraction and when small, ramp-shaped length-releases were applied to these fibers. This maneuver allows a transient accumulation of cross-bridges in states near the end of their power stroke. By lowering the temperature to 5 degrees C, force transients were slowed sufficiently to record diffraction patterns in several 2-4-ms time frames before and during such releases, using the RAPID detector (Refined ADC Per Input Detector) at beam line ID02 of the European Synchrotron Radiation Facility (Grenoble, France). The same sequence of frames was recorded in relaxation and rigor. Comparisons of 2D patterns recorded during isometric contraction, with patterns recorded at different [MgATPgammaS] and at 1 degrees C, showed that changes in intensity profiles along the first and sixth actin layer lines (ALL1 and ALL6, respectively) allowed for discernment of the formation of rigor or rigor-like cross-bridges. During ramp-shaped releases of activated fibers, intensity profiles along ALL1 and ALL6 did not reveal evidence for the accumulation of rigor-like cross-bridges. Instead, changes in the ALL6-profile suggest that during ramp-shaped releases, cross-bridges transiently accumulate in a structural state that, to our knowledge, was not previously seen, but that could well be a strongly bound state with the light-chain binding domain in a conformation between a near prepower-stroke (isometric) orientation and the orientation in rigor.

Do we need a cancer screening in patients with idiopathic deep vein thrombosis?

AIM

To review the literature concerning the need for a cancer screening battery to diagnose a hidden cancer in patients presenting with idiopathic venous thromboembolism (VTE).

MATERIALS AND METHODS

Data from computerized database programs (Medline, Ovid) was retrieved. A review of the literature regarding studies on cancer screening in patients with idiopathic VTE was performed and our own policy included.

RESULTS

Patients with VTE have a higher rate of malignancy which may still be undiagnosed. During follow-up of patients with idiopathic VTE, the incidence of cancer increases and is more likely associated with a worse prognosis. Limited diagnostic work-up in patients with idiopathic VTE allows the diagnosis of a hidden malignancy in about half of the cases with a sensitivity of 48 %. Extensive screening of cancer with idiopathic VTE allows less of a delay and earlier stage at diagnosis with a 93 % sensitivity. However, reduced cancer-related mortality is not statistically significant. A two-fold fatal PE and more than 3-fold fatal bleeding are registered in VTE patients with hidden cancer compared to patients without cancer. The major risk factors for hidden cancer are old age, anemia, idiopathic and bilateral deep vein thrombosis.

CONCLUSION

There is no consensus regarding the benefit of extensive screening in patients presenting with idiopathic VTE. Clear diagnostic work-up guidelines are not yet available. A cost-effective diagnostic algorithm for cancer screening in patients with idiopathic VTE is needed.

A new detection system for extremely small vertically mounted cantilevers

Detection techniques currently used in scanning force microscopy impose limitations on the geometrical dimensions of the probes and, as a consequence, on their force sensitivity and temporal response. A new technique, based on scattered evanescent electromagnetic waves (SEW), is presented here that can detect the displacement of the extreme end of a vertically mounted cantilever. The resolution of this method is tested using different cantilever sizes and a theoretical model is developed to maximize the detection sensitivity. The applications presented here clearly show that the SEW detection system enables the use of force sensors with sub-micron size, opening new possibilities in the investigation of biomolecular systems and high speed imaging. Two types of cantilevers were successfully tested: a high force sensitivity lever with a spring constant of 0.17 pN nm(-1) and a resonant frequency of 32 kHz; and a high speed lever with a spring constant of 50 pN nm(-1) and a resonant frequency of 1.8 MHz. Both these force sensors were fabricated by modifying commercial microcantilevers in a focused ion beam system. It is important to emphasize that these modified cantilevers could not be detected by the conventional optical detection system used in commercial atomic force microscopes.

Administration off label of recombinant factor-VIIa (rFVIIa) to patients with blunt or penetrating brain injury without coagulopathy

Traumatic brain contusions may increase in size over time or may develop at a delay after injury. This may lead to neurological deterioration, long term morbidity or even death. Coagulation disorders after injury can contribute to progression of haemorrhage. Recombinant activated factor VII (rFVIIa) was used in 12 patients with a severe head injury who had no systemic coagulopathy but who were considered to be at risk of progression of their intracranial lesion. Twelve consecutive patients suffering from life-threatening acute head injuries from blunt (3 cases) and penetrating mechanisms were given with rFVIIa, either to prevent the expected development of brain contusion or to assist in bleeding control during surgery. In 11 patients, rFVIIa was given by the attending neurosurgeon. Two of the patients died of their severe penetrating injuries one of whom had severe vasospasm 2 days after administration of rFVIIa. The other 11 patients did not appear to suffer any treatment-related adverse effects. When the drug was given prophylactically to prevent brain resection (6 cases) or to limit the need for widening resection (5 cases), marked control was achieved in seven cases, and a lesser effect was observed in the other 4 cases. We conclude that, in a small and highly individually selected series of patients with severe head injury, the administration of rFVIIa did not lead to adverse effects. Although the majority of patients were considered to be at high risk of progression of their lesions, this occurred in only one. The early use of rFVIIa in head injured patients without systemic coagulopathy may reduce the occurrence of enlargement of contusions, the requirement of further operation, and adverse outcome. Prospective randomised controlled studies are required to investigate this.