Circulating tumor DNA as an early marker of therapeutic response in patients with metastatic colorectal cancer

BACKGROUND

Early indicators of treatment response in metastatic colorectal cancer (mCRC) could conceivably be used to optimize treatment. We explored early changes in circulating tumor DNA (ctDNA) levels as a marker of therapeutic efficacy.

PATIENTS AND METHODS

This prospective study involved 53 mCRC patients receiving standard first-line chemotherapy. Both ctDNA and CEA were assessed in plasma collected before treatment, 3 days after treatment and before cycle 2. Computed tomography (CT) scans were carried out at baseline and 8-10 weeks and were centrally assessed using RECIST v1.1 criteria. Tumors were sequenced using a panel of 15 genes frequently mutated in mCRC to identify candidate mutations for ctDNA analysis. For each patient, one tumor mutation was selected to assess the presence and the level of ctDNA in plasma samples using a digital genomic assay termed Safe-SeqS.

RESULTS

Candidate mutations for ctDNA analysis were identified in 52 (98.1%) of the tumors. These patient-specific candidate tissue mutations were detectable in the cell-free DNA from the plasma of 48 of these 52 patients (concordance 92.3%). Significant reductions in ctDNA (median 5.7-fold; P < 0.001) levels were observed before cycle 2, which correlated with CT responses at 8-10 weeks (odds ratio = 5.25 with a 10-fold ctDNA reduction; P = 0.016). Major reductions (≥10-fold) versus lesser reductions in ctDNA precycle 2 were associated with a trend for increased progression-free survival (median 14.7 versus 8.1 months; HR = 1.87; P = 0.266).

CONCLUSIONS

ctDNA is detectable in a high proportion of treatment naïve mCRC patients. Early changes in ctDNA during first-line chemotherapy predict the later radiologic response.

Surgery for the correction of hallux valgus

This study sought to determine the medium-term patient-reported and radiographic outcomes in patients undergoing surgery for hallux valgus. A total of 118 patients (162 feet) underwent surgery for hallux valgus between January 2008 and June 2009. The Manchester-Oxford Foot Questionnaire (MOXFQ), a validated tool for the assessment of outcome after surgery for hallux valgus, was used and patient satisfaction was sought. The medical records and radiographs were reviewed retrospectively. At a mean of 5.2 years (4.7 to 6.0) post-operatively, the median combined MOXFQ score was 7.8 (IQR:0 to 32.8). The median domain scores for pain, walking/standing, and social interaction were 10 (IQR: 0 to 45), 0 (IQR: 0 to 32.1) and 6.3 (IQR: 0 to 25) respectively. A total of 119 procedures (73.9%, in 90 patients) were reported as satisfactory but only 53 feet (32.7%, in 43 patients) were completely asymptomatic. The mean (SD) correction of hallux valgus, intermetatarsal, and distal metatarsal articular angles was 18.5° (8.8°), 5.7° (3.3°), and 16.6° (8.8°), respectively. Multivariable regression analysis identified that an American Association of Anesthesiologists grade of > 1 (Incident Rate Ratio (IRR) = 1.67, p-value = 0.011) and recurrent deformity (IRR = 1.77, p-value = 0.003) were associated with significantly worse MOXFQ scores. No correlation was found between the severity of deformity, the type, or degree of surgical correction and the outcome. When using a validated outcome score for the assessment of outcome after surgery for hallux valgus, the long-term results are worse than expected when compared with the short- and mid-term outcomes, with 25.9% of patients dissatisfied at a mean follow-up of 5.2 years.

Cite this article: Bone Joint J 2015;97-B:208–14.

A longitudinal cohort study evaluating the impact of a geriatrician-led residential care outreach service on acute healthcare utilisation

BACKGROUND

over the last decade, high demand for acute healthcare services by long-term residents of residential care facilities (RCFs) has stimulated interest in exploring alternative models of care. The Residential Care Intervention Program in the Elderly (RECIPE) service provides expert outreach services to RCFs residents, interventions include comprehensive care planning, management of inter-current illness and rapid access to acute care substitution services.

OBJECTIVE

to evaluate whether the RECIPE service decreased acute healthcare utilisation.

DESIGN

a retrospective cohort study using interrupted time series analysis to analyse change in acute healthcare utilisation before and after enrolment.

SETTING

a 300-bed metropolitan teaching hospital in Australia and 73 RCFs within its catchment.

SUBJECTS

there were 1,327 patients enrolled in the service with a median age of 84 years; 61% were female.

METHODS

data were collected prospectively on all enrolled patients from 2004 to 2011 and linked to the acute health service administrative data set. Primary outcomes change in admission rates, length of stay and bed days per quarter.

RESULTS

in the 2 years prior to enrolment, the mean number of acute care admissions per patient per year was 3.03 (SD 2.9) versus post 2.4 (SD 3.3), the service reducing admissions by 0.13 admissions per patient per quarter (P = 0.046). Prior to enrolment, the mean length of stay was 8.6 (SD 11.0) versus post 3.5 (SD 5.0), a reduction of 1.5 days per patient per quarter (P = 0.003).

CONCLUSIONS

this study suggests that an outreach service comprising a geriatrician-led multidisciplinary team can reduce acute hospital utilisation rates.

What are the similarities and differences in antimicrobial prescribing between Australian public and private hospitals?

BACKGROUND

Identifying themes associated with inappropriate prescribing in Australian public and private hospitals will help target future antimicrobial stewardship initiatives.

AIMS

To describe current antimicrobial prescribing practices, identify similarities and differences between hospital sectors and provide target areas for improvement specific to each hospital sector.

METHODS

All hospitals included in the study were part of the 2014 national antimicrobial prescribing survey and conducted one of the following: a whole hospital point prevalence survey, serial point prevalence surveys or a sample of randomly selected patients. Data on the types of antibiotics used, their indications for use and the quality of prescription based on compliance with national and local prescribing guidelines were collected.

RESULTS

Two hundred and two hospitals (166 public and 36 private) comprising 10 882 patients and 15 967 antimicrobial prescriptions were included. Public hospitals had higher proportions of prescriptions for treatment (81.5% vs 48.4%) and medical prophylaxis (8.8% and 4.6%), whilst private hospitals had significantly higher surgical prophylaxis use (9.6% vs 46.9%) (P < 0.001). In public hospitals, the main reasons for non-compliance of treatment prescriptions were spectrum being too broad (30.5%) while in private it was incorrect dosing. Prolonged duration was the main reason for non-compliance among surgical prophylaxis prescriptions in both types of hospitals.

CONCLUSIONS

Australian hospitals need to target specific areas to improve antimicrobial use. Specifically, unnecessary broad-spectrum therapy should be a priority area in public hospitals, whilst emphasis on curtailing antimicrobial overuse in surgical prophylaxis needs to be urgently addressed across in the private hospital sector.

Spinal infections in older people: an analysis of demographics, presenting features, microbiology and outcomes

BACKGROUND

Clinical features of infection can become more atypical as we age. Spinal infections can be insidious, and timely diagnosis and treatment are essential to prevent adverse outcomes.

AIMS

To explore differences in presentation and outcomes between younger and older patients with bacterial spinal infections.

METHODS

Clinical, microbiological and radiological information was collected for patients with spinal infections (spondylodiscitis, vertebral osteomyelitis, septic discitis, facet joint septic arthritis and spinal epidural abscess) at a single metropolitan hospital between January 2008 and January 2015. Patients were excluded if they were under 18 years of age or if clinical and imaging findings were inconsistent with the diagnosis. Presenting features, investigations and outcomes were compared for patients ≥65 (older) or <65 (younger) years old.

RESULTS

Of 53 identified patients, 34 (64%) were classified as older, with more males in both older (65%) and younger (79%) groups. Older patients presented later (median symptom duration 13 vs 4 days, P = 0.016). Back pain was nearly ubiquitous. Older patients presented less commonly with fevers (38 vs 63%) and rigors (24 vs 42%) but more commonly with hypotension (18 vs 5%), delirium (24 vs 11%), higher median inflammatory marker levels and variable microbiological findings, although these differences were not statistically significant. They had longer median lengths of stay (24 vs 14 days) and a higher likelihood of death or failure of medical treatment (HR 9.34, P = 0.031). Radicular pain was associated with poor outcome (HR 3.29, P = 0.046).

CONCLUSION

Older patients with spinal infections present later, with higher inflammatory markers and fewer typical infective symptoms and signs; these may contribute to poorer outcomes. A low threshold for promptly investigating older patients with new or worsening back pain should be set.

Proximal versus distal screw placement for biceps tenodesis: a biomechanical study

PURPOSE

To assess the maximum and end torque of a fourth-generation composite humerus model with no screw inserted or with a screw inserted in the distal (subpectoral) position or proximal (suprapectoral) position.

METHODS

24 large-size, fourth-generation composite humeri were randomised to the control (n=8), proximal (n=8), or distal (n=8) group. For the latter 2 groups, an 8-mm-head interference screw (7x25 mm) was inserted at 1 cm proximal and 1 cm distal to the superior aspect of the insertion of the pectoralis major tendon, respectively. The maximum and end torque of each humerus was assessed.

RESULTS

Respectively for the control, proximal, and distal groups, the maximum torque was 81.8, 78.7, and 74.3 Nm, and the end torque was 80.7, 78.6, and 71.8 Nm; only the difference between control and distal groups was significant (p=0.005 for maximum torque and p=0.033 for end torque). All fractures in both control and proximal groups involved the distal 1/3 humerus. In the distal group, the fractures involved either the distal 1/3 humerus (n=6) or the screw-hole (n=2); the difference between the 2 types of fracture was not significant in terms of maximum torque (75.7 vs. 70.0, p=0.086) or end torque (75.3 vs. 61.4, p=0.40).

CONCLUSION

Compared with proximal placement of an interference screw, distal placement decreased the maximum torque (though not significantly) and may increase the risk of proximal humeral fracture.

The minimal leak test technique for endotracheal cuff maintenance

Endotracheal tube (ETT) cuff pressure management is an essential part of airway management in intubated and mechanically ventilated patients. Both under- and over-inflation of the ETT cuff can lead to patient complications, with an ideal pressure range of 20-30 cmH₂O defined. A range of techniques are employed to ensure adequate ETT cuff inflation, with little comparative data. We performed an observational cross-sectional study in a tertiary metropolitan ICU, assessing the relationship between the minimal leak test and cuff manometry. Forty-five mechanically ventilated patients, over a three-month period, had ETT cuff manometry performed at the same time as their routine cuff maintenance (minimal leak test). Bedside nurse measurements were compared with investigator measurements. At the endpoint of cuff inflation, 20 of 45 patients (44%) had cuff pressures between 20 and 30 cmH₂O; 11 of 45 patients (24%) had cuff pressures <20 cmH₂O; 14 of 45 patients (31%) had cuff pressures ≥30 cmH₂O. Univariate analysis demonstrated an association between both patient obesity and female gender requiring less ETT cuff volume (P=0.008 and P <0.001 respectively), though this association was lost on multivariate analysis. No association was demonstrated between any measured variables and cuff pressures. Inter-operator reliability in performing the minimal leak test showed no evidence of bias between nurse and investigators (Pearson coefficient = 0.897). We conclude the minimal leak test for maintenance of ETT cuffs leads to both over- and under-inflation, and alternative techniques, such as cuff manometry, should be employed.

Vertebral Fractures Following Stereotactic Body Radiotherapy for Spine Oligometastases: A Multi-institutional Analysis of Patient Outcomes

AIMS

Stereotactic body radiotherapy (SBRT) is a locally ablative therapy used for the treatment of patients with spine metastases. However, it is associated with higher rates of vertebral compression fractures (VCF) than conventionally fractionated palliative radiotherapy. The purpose of this study was to determine the rate of VCF following spine SBRT and to identify the risk factors associated with this outcome.

MATERIALS AND METHODS

We retrospectively reviewed patients treated at two Australian institutions from January 2015 to March 2019. Descriptive statistics were used to assess patient, tumour and treatment factors. The Log-rank test and Cox proportional hazards model were applied in univariate and multivariable analyses to identify factors associated with VCF, local control and overall survival.

RESULTS

We evaluated 113 spinal segments from 84 patients, with a median follow-up time of 11.9 months. The median dose and fractionation utilised was 30 Gy in three fractions (67.3%), with a single-fraction rate of 0.9%. The median Spinal Instability Neoplastic Score (SINS) of the lesions was 4/18, with most (84.1%) being SINS stable, scoring between 0 and 6. Five VCFs were observed (three progression of pre-existing fractures and two de novo), a cumulative VCF risk of 4.4%. Four of five fractures occurred within the first year after treatment, with a median time to VCF of 9.2 months. A pre-existing VCF (P = 0.011) was associated with subsequent fracture on multivariable analysis, whereas all VCF segments displayed lytic disease appearance. All fractures were managed conservatively with analgesia, without requirement for subsequent surgical intervention.

CONCLUSION

SBRT to spine metastases is safe with respect to VCF, with rates around the lower limit observed in similar studies. Knowledge of factors that predispose to post-treatment fracture, such as pre-existing compression, lytic vertebral disease and SINS >6 will aid in the counselling and selection of patients for this therapy.

Assessment of Intrafraction Motion of the Urinary Bladder Using Magnetic Resonance Imaging (cineMRI)

AIM

To assess the intrafraction motion of the urinary bladder and delineate the appropriate margin size for radiotherapy planning, for both the full and empty bladder.

MATERIALS AND METHODS

This was a single-site, single-arm study of 20 patients planned to undergo radical cystectomy for histologically confirmed muscle-invasive bladder cancer. Patients underwent magnetic resonance imaging (cineMRI) of the entire pelvis using a 3-Tesla system, prior to cystectomy. Patients first underwent a cineMRI with a full bladder, then voided and underwent a second MRI with an empty bladder. All MRI sequences were acquired over 18 min. We assessed the differences in bladder filling and subsequent bladder wall displacement, between the empty and full bladder, during a time period consistent with radiotherapy treatment delivery.

RESULTS

Twenty patients underwent cineMRI of the entire pelvis. The maximum mean directional displacements of the bladder walls over the 18 min duration of the scan for the empty bladders were 9.8 mm superiorly, 1.1 mm inferiorly, 2.39 mm anteriorly, 3.73 mm posteriorly, 2.74 mm to the left and 2.48 mm to the right. The maximal mean displacements for the full bladders were 9.2 mm superiorly, 1.1 mm inferiorly, 2.28 mm anteriorly, 1.08 mm posteriorly, 1.85 mm to the left and 1.73 mm to the right. Statistically significant differences were seen in the posterior, left and right displacements but were quantitatively small.

CONCLUSIONS

Intrafractional motion secondary to bladder filling showed minimal variation between the full and empty bladder. Similar clinical target volume to planning target volume margins can be applied for the delivery of radiotherapy for a full and empty bladder.

Non-Animal Stabilized Hyaluronic Acid (NASHA) Gel Marker vs. Surgical Clips for Tumor Bed Delineation in Breast Cancer Using MR-Simulation

PURPOSE/OBJECTIVE(S)

Consistent delineation of the tumor bed (TB) after breast conserving surgery (BCS) is critical and remains a challenge with increasing prevalence of oncoplastic surgeries. Clips are generally used to help TB identification on CT-simulation but they are not well identified on MR-simulation. The aim of this study is to assess whether the use of NASHA gel with MR-simulation yields similar interobserver variability (inter-OV) compared to clips with CT-simulation.

MATERIALS/METHODS

This prospective single arm feasibility study included patients eligible for BCS. After lumpectomy, the surgeon placed both clips (>5) and NASHA gel drops as markers to define the TB. Patients underwent CT and MRI simulation scans. Five radiation oncologists and one radiologist delineated the TB aided by clips on CT, and gel on MRI. The observers also assessed the visibility and utility of the gel (scale from 1 to 10), as well as the cavity visualization score (CVS, scale from 1 to 5). The primary endpoint was the inter-OV of the delineated TB using the overlap difference of contours using clips and CT versus gel and MRI, with the conformity index measured according to the pair definition of the Dice Similarity Coefficient (DSC).

RESULTS

Of the 35 patients recruited, 30 were eligible for inter-OV analysis of TB delineation and 5 patients required further breast surgery for positive margins. One third of the eligible patients underwent an oncoplastic procedure. There were no significant differences between inter-OV of delineated TB using clips and CT versus gel and T2-weighted MRI with the mean DSC (0.60 vs 0.62, p = 0.364). The observers reported higher usefulness of gel in patients with an oncoplastic procedure than not (median US 8.2 vs 6.6, p = 0.024), and higher visibility of gel in patients who had their scans within 6 weeks than beyond post-op (median VS 8.1 vs 6.1, p = 0.013). When the CVS was higher (3-5), the median US of gel was lower (5.9 vs 7.8, p = 0.004), and the conformity index of clip and CT delineated TB was higher (median DSC 0.72 vs 0.53, p <0.001). Interestingly, a higher CVS did not lead to significantly higher conformity index of gel and T2-weighted MR delineated TB (mean DSC 0.67 vs 0.58, p = 0.073). NASHA gel injection added a median of 3 minutes to the operating theatre (OT) time and was rated as 'easy' in 89% of cases by surgeons. There were no immediate adverse events (AE) in OT, while 2 of 35 patients later experienced a grade 3 AE - hematoma which required evacuation in OT day 1 post-BCS, and infected seroma which required drainage and washout in OT 2 months post-BCS and axillary dissection. These reflect common risks with standard BCS and are not clearly attributed to gel injection alone.

CONCLUSION

Use of NASHA gel leads to similar inter-OV of BC TB delineation compared to >5 clips. NASHA gel is hence a reliable alternative to clips when MR-simulation is used.

P858High endothelial shear stress and local Reynolds number are associated with lipid growth of coronary plaques

Background

Local haemodynamic disturbances in coronary blood flow are associated with abnormal endothelial shear stress (ESS) and progressive atherosclerosis. However, standard techniques to estimate ESS lack the diagnostic specificity necessary for future clinical utility. Possible improvements include use of a more realistic non-Newtonian model of blood, which may provide more accurate ESS measurements and is further able to detect local variations in blood viscosity.

Purpose

To compare accuracy of ESS generated by Newtonian versus non-Newtonian rheological models to detect coronary plaque progression. To investigate local Reynolds number (ReL), a viscosity-based haemodynamic metric calculated by the non-Newtonian model, as an independent marker of plaque progression.

Methods

Sixteen patients with non-culprit plaques completely visualised in serial optical coherence tomography (OCT) imaging were identified. Plaques were analysed in 0.2mm intervals at each timepoint for lipid and calcium arc. Computational fluid dynamic simulations were performed using Newtonian and non-Newtonian models to calculate ESS, whereas ReL was calculated by the non-Newtonian simulations. Each haemodynamic index was compared to interval changes in lipid and calcium using multivariate regression.

Results

In total, 894 matched arterial segments from baseline and follow up imaging were analysed. In the Newtonian results, baseline segments exposed to ESS>1.7Pa had a 12.5° increase in lipid arc (95% CI 2.2° to 22.8°, p=0.018) while segments exposed to ESS<1.1Pa had an 8.1° decrease in calcium (95% CI −14.0° to −2.2°, p=0.007). In the non-Newtonian results, baseline regions exposed to ESS>2.2Pa had a 14.4° increase in lipid (95% CI 4.2° to 24.7°, p=0.006) while areas with ESS<1.4Pa had an 8.7° decrease in calcium (95% CI −14.6° to −2.8°, p=0.004). Baseline regions exposed to ReL<34 showed an average 11.9° increase in lipid arc (95% CI 0.6° to 23.2°, p=0.039). Regions exposed to ReL>55 had an average increase in lipid arc of 26.6° (95% CI 14.5° to 38.6°, p<0.001).

Conclusions

Both Newtonian and non-Newtonian rheological models show that high ESS is associated with increased lipid while low ESS is associated with decreased calcium. ReL is independently associated with interval increases in lipid arc, suggesting a mechanistic role of local blood viscosity in lipid accumulation. ReL may serve as a novel haemodynamic marker of plaque progression.

P2433Local blood viscosity and local Reynolds number are associated with coronary plaque calcium and lipid

Background

Despite being a shear-thinning non-Newtonian fluid, most computational fluid dynamic (CFD) simulations assume blood to be a Newtonian fluid with constant viscosity. The use of more realistic assumptions may deepen mechanistic understanding of the relationship between blood flow disturbances and atherosclerosis, and improve the diagnostic accuracy of CFD simulations.

Purpose

To compare associations between plaque composition and local hemodynamics at a single time point using Newtonian versus non-Newtonian rheological models in patient-specific coronary arteries. To investigate whether viscosity-based local haemodynamic indices correlate with plaque composition.

Methods

Sixteen patient-specific coronary arteries containing non-culprit plaques were reconstructed from optical coherence tomography imaging. CFD simulations using Newtonian and non-Newtonian models were performed to calculate endothelial shear stress (ESS). Local blood viscosity (LBV) and local Reynolds number (ReL) were calculated from non-Newtonian simulation data. Each haemodynamic index was distributed into quintiles, mapped in 5-degree sectors, and compared to plaque composition using logistic regression.

Results

In total, 69120 sectors from 960 OCT frames were analysed. The lowest ESS quintiles were associated with underlying lipid (ESS<0.8Pa: odds ratio [OR] 1.26, p<0.001, 95% CI 1.15–1.38; ESS 0.8–1.1Pa: OR 1.71, p<0.001, 95% CI 1.58–1.85), while the highest quintile of ESS (>2.2Pa) had lower odds of underlying lipid (OR 0.89, p=0.015, 95% CI 0.82–0.98) compared to the median ESS quintile. However, in the non-Newtonian results, only the second lowest quintile of ESS (1.1–1.5Pa) was associated with lipid (OR 1.54, p<0.001, 95% CI 1.42–1.67). Low ReL was associated with lipid (ReL<28: OR 1.71, p<0.001, 95% CI 1.55–1.89; ReL 28–38: OR 1.47, p<0.001, 95% CI 1.35–1.58). Conversely, the highest quintile of ReL had decreased odds of lipid (ReL>68: OR 0.69, p<0.001, 95% CI 0.62–0.76) (FIGURE). In both the Newtonian and non-Newtonian results, lower ESS was associated with increased odds of underlying calcium. Whereas the lowest quintile of LBV had a lower odds of calcium (LBV<1.4: OR 0.60, p<0.001, 95% CI 0.52–0.71), the highest quintile had significantly higher odds of underlying calcium (LBV>1.5: OR 1.38, p<0.001, 95% CI 1.18–1.63)

Conclusions

Using the standard Newtonian assumption, low ESS is associated with underlying lipid. However, using a more realistic non-Newtonian rheological model, there is no strong or consistent relationship between ESS and underlying lipid, highlighting the importance of methodological assumptions and lingering questions in arterial CFD simulation. Non-Newtonian indices LBV and ReL are independently associated with calcium and lipid, respectively, suggesting possible mechanistic effects of local blood viscosity in atherosclerosis and implying their use as novel haemodynamic markers of atherosclerosis.