Imaging hypoxia to improve radiotherapy outcome Horsman, Michael R; Mortensen, Lise Saksø; Petersen, Jørgen B ...
Nature reviews. Clinical oncology,
12/2012, Letnik:
9, Številka:
12
Journal Article
Recenzirano
Reduced oxygen levels (hypoxia) is one of the most important factors influencing clinical outcome after radiotherapy. This is primarily because hypoxic cells are resistant to radiation treatment; ...hence, the greater the number of clonogenic cancer stem cells that exist under hypoxia, the lower the local tumour control. Reduced local control will influence overall survival, as may the hypoxic conditions by increasing malignant progression; however, to fight hypoxia, we should first be able to see it. We need noninvasive approaches that can accurately and reliably image hypoxia in tumours, especially using techniques that are routinely available in the clinic, such as PET, MRI and CT. All these imaging methods are already under clinical evaluation in this context. Such data should allow us to identify those patients on an individual basis who have hypoxic tumours and, thus, at the very least should receive some form of hypoxic modifier in conjunction with radiotherapy. Alternatively, the radiation dose could be either increased to the whole tumour or, if the imaging is accurate enough, only to the hypoxic subvolumes. The aim of this Review is to critically assess the potential use of imaging to help improve clinical outcome to radiotherapy.
Abstract
LET-painting was suggested as a method to overcome tumour hypoxia. In vitro experiments have demonstrated a well-established relationship between the oxygen enhancement ratio (OER) and ...linear energy transfer (LET), where OER approaches unity for high-LET values. However, high-LET radiation also increases the risk for side effects in normal tissue. LET-painting attempts to restrict high-LET radiation to compartments that are found to be hypoxic, while applying lower LET radiation to normoxic tissues. Methods. Carbon-12 and oxygen-16 ion treatment plans with four fields and with homogeneous dose in the target volume, are applied on an oropharyngeal cancer case with an identified hypoxic entity within the tumour. The target dose is optimised to achieve a tumour control probability (TCP) of 95% when assuming a fully normoxic tissue. Using the same primary particle energy fluence needed for this plan, TCP is recalculated for three cases assuming hypoxia: first, redistributing LET to match the hypoxic structure (LET-painting). Second, plans are recalculated for varying hypoxic tumour volume in order to investigate the threshold volume where TCP can be established. Finally, a slight dose boost (5-20%) is additionally allowed in the hypoxic subvolume to assess its impact on TCP. Results. LET-painting with carbon-12 ions can only achieve tumour control for hypoxic subvolumes smaller than 0.5 cm3. Using oxygen-16 ions, tumour control can be achieved for tumours with hypoxic subvolumes of up to 1 or 2 cm3. Tumour control can be achieved for tumours with even larger hypoxic subvolumes, if a slight dose boost is allowed in combination with LET-painting. Conclusion. Our findings clearly indicate that a substantial increase in tumour control can be achieved when applying the LET-painting concept using oxygen-16 ions on hypoxic tumours, ideally with a slight dose boost.
The aim of this study was to assess acute and late morbidity measured by the physician and patient-reported outcomes (PROs) in high-risk prostate cancer (PC) patients receiving whole pelvic ...intensity-modulated radiotherapy (IMRT) in the setting of a national clinical trial.
A total of 88 patients with adenocarcinoma of the prostate and high-risk parameters were enrolled from 2011 to 2013. All patients received 78 Gy in 39 fractions of IMRT delivering simultaneous 78 Gy to the prostate and 56 Gy to the seminal vesicles and lymph nodes. Physician-reported morbidity was assessed by CTCAE v.4.0. PROs were registered for gastro-intestinal (GI) by the RT-ARD score, genito-urinary (GU) by DAN-PSS, sexual and hormonal by EPIC-26, and quality of life (QoL) by EORTC QLQ-C30.
Median follow-up (FU) time was 4.6 years. No persistent late CTCAE grade 3+ morbidity was observed. Prevalence of CTCAE grade 2+ GI morbidities varied from 0 to 6% at baseline throughout FU time, except for diarrhea, which was reported in 19% of the patients post-RT. PROs revealed increased GI morbidity (≥1 monthly episode) for "rectal urgency", "use of pads", "incomplete evacuation", "mucus in stool" and "bowel function impact on QoL" all remained significantly different (p < .05) at 60 months compared to baseline. CTCAE grade 2+ GU and sexual morbidity were unchanged. GU PROs on obstructive and irritative GU items (≥daily episode) increased during RT and normalized at 24 months. No clinically significant differences were found in sexual, hormonal, and QoL scores compared to baseline.
Whole pelvic RT resulted in a mild to the moderate burden of late GI morbidities demonstrated by a relatively high prevalence of PROs. Whereas, physician-assessed morbidity revealed a low prevalence of late GI morbidity scores. This emphasizes the importance of using both PROs and physician-reported scoring scales when reporting late morbidity in clinical trials.
Abstract Purpose Patients with urinary bladder cancer are obvious candidates for adaptive radiotherapy (ART) due to large inter-fractional variation in bladder volumes. In this study we have compared ...the normal tissue sparing potential of two ART strategies: daily plan selection (PlanSelect) and daily plan re-optimisation (ReOpt). Materials and methods Seven patients with bladder cancer were included in the study. For the PlanSelect strategy, a patient-specific library of three plans was generated, and the most suitable plan based on the pre-treatment cone beam CT (CBCT) was selected. For the daily ReOpt strategy, plans were re-optimised based on the CBCT from each daily fraction. Bladder contours were propagated to the CBCT scan using deformable image registration (DIR). Accumulated dose distributions for the ART strategies as well as the non-adaptive RT were calculated. Results A considerable sparing of normal tissue was achieved with both ART approaches, with ReOpt being the superior technique. Compared to non-adaptive RT, the volume receiving more than 57 Gy (corresponding to 95% of the prescribed dose) was reduced to 66% (range 48–100%) for PlanSelect and to 41% (range 33–50%) for ReOpt. Conclusion This study demonstrated a considerable normal tissue sparing potential of ART for bladder irradiation, with clearly superior results by daily adaptive re-optimisation.
•Phospholipids impacts the accuracy of senicapoc determinations in plasma by LC–MS/MS.•Phospholipids can be removed by SPE filtration without loss of senicapoc.•Rapid and accurate quantification of ...senicapoc in plasma from COVID-19 patients.
The clinically tested KCa3.1 channel blocker, senicapoc, has been proven to have excellent pharmacological properties and prior clinical trials found it to be safe for use in patients with sickle cell anaemia. Currently, several preclinical projects are aiming to repurpose senicapoc for other indications, but well-described analytical methods in the literature are lacking. Our aim was to develop a sensitive, rapid and accurate ultra-high-performance liquid chromatography-tandem mass spectrometry method using pneumatically assisted electrospray ionisation (UHPLC-ESI-MS/MS) suitable for the determination of senicapoc in plasma samples. Unfortunately, direct analysis of senicapoc in crude acetonitrile extracts of human plasma samples by UHPLC-ESI-MS/MS was subjected to significant and variable ion suppression from coeluting phospholipids (PLs). The interferences were mainly caused by the presence of phosphatidylcholine and phosphatidylethanolamine classes of PLs, including their lyso-products. However, the PLs were easily removed from crude extracts by filtration through a sorbent with Lewis acid properties which decreased the total ion suppression effect to approximately 5%. Based on this technique, a simple high-throughput UHPLC-MS/MS method was developed and validated for the determination of senicapoc in 100-μL plasma samples. The lower limit of quantification was 0.1 ng/mL. The mean true extraction recovery was close to 100 %. The relative intra-laboratory reproducibility standard deviations of the measured concentrations were 8% and 4% at concentrations of 0.1 ng/mL and 250 ng/mL, respectively. The trueness expressed as the relative bias of the test results was within ± 2% at concentrations of 1 ng/mL or higher.
Chemoradiotherapy (CRT) is the standard therapy for localized anal cancer (AC), but this treatment is associated with substantial toxicity. However, there is a lack of prospectively collected ...toxicity and patient reported outcome (PRO) data from larger cohorts.
The purpose was to prospectively collect and determine agreement between physician assessed toxicity (CTCAE) and PRO during and after CRT and to compare IMRT, VMAT and proton-based planning in a subgroup of patients.
Patients, treated with CRT for AC, were included between 2015 and 2017. NCI-CTCAE v.4.0, EORTC QLQ-C30 and CR29 data were collected baseline, mid-therapy, end-of therapy and 2–4 weeks posttherapy. Treatment planning with 5- or 6-fixed field IMRT, 2 and 3 arc VMAT, and 3- and 4-field proton plans were compared.
One-hundred patients were included. Both CTCAE and PROs related to acute toxicity reached a maximum at end of therapy. Incidences of PROs were markedly higher with only slight to fair agreement to CTCAE, (κ 13–37). Comparative planning revealed dosimetric equality of IMRT and VMAT plans, but superiority of proton plans.
The high incidence of PRO scores and weak agreement to CTCAE suggest that PROs are important tools complementary to CTCAE in evaluating patient symptoms during and after CRT. Proton therapy has the potential to lower radiation doses to most organs at risk.
Abstract
Tumour hypoxia is one of the limiting factors in obtaining tumour control in radiotherapy. The high-LET region of a beam of heavy charged particles such as carbon ions is located in the ...distal part of the Bragg peak. A modulated or spread out Bragg peak (SOBP) is a weighted function of several Bragg peaks at various energies, which however results in a dilution of the dose-average LET in the target volume. Here, we investigate the possibility to redistribute the LET by dedicated treatment plan optimisation, in order to maximise LET in the target volume. This may be a strategy to potentially overcome hypoxia along with dose escalation or dose painting. The high-LET region can be shaped in very different ways, while maintaining the distribution of the absorbed dose or biological effective dose. Treatment plans involving only carbon ion beams, show very different LET distributions depending on how the fields are arranged. Alternatively, a LET boost can be applied in multi-modal treatment planning, such as combining carbon ions with protons and/or photons. For such mixed radiation modalities, significant "LET boosts" can be achieved at nearly arbitrary positions within the target volume. Following the general understanding of the relationship between hypoxia, LET and the oxygen enhancement ratio (OER), we conclude, that an additional therapeutic advantage can be achieved by confining the high-LET part of the radiation in hypoxic compartments of the tumour, and applying low-LET radiation to the normoxic tissue. We also anticipate that additional advantages may be achieved by deliberate sparing of normal tissue from high LET regions. Consequently, treatment planning based on simultaneous dose and LET optimisation has a potential to achieve higher tumour control and/or reduced normal tissue control probability (NTCP).
Abstract Background Progression of non–muscle-invasive bladder cancer (NMIBC) to muscle-invasive bladder cancer (MIBC) is life-threatening and cannot be accurately predicted using clinical and ...pathological risk factors. Biomarkers for stratifying patients to treatment and surveillance are greatly needed. Objective To validate a previously developed 12-gene progression score to predict progression to MIBC in a large, multicentre, prospective study. Design, setting, and participants We enrolled 1224 patients in ten European centres between 2008 and 2012. A total of 750 patients (851 tumours) fulfilled the inclusion and sample quality criteria for testing. Patients were followed for an average of 28 mo (range 0–76). A 12-gene real-time qualitative polymerase chain reaction assay was performed for all tumours and progression scores were calculated using a predefined formula and cut-off values. Outcome measurements and statistical analysis We measured progression to MIBC using Cox regression analysis and log-rank tests for comparing survival distributions. Results and limitations The progression score was significantly ( p < 0.001) associated with age, stage, grade, carcinoma in situ, bacillus Calmette-Guérin treatment, European Organisation for Research and Treatment of Cancer risk score, and disease progression. Univariate Cox regression analysis showed that patients molecularly classified as high risk experienced more frequent disease progression (hazard ratio 5.08, 95% confidence interval 2.2–11.6; p < 0.001). Multivariable Cox regression models showed that the progression score added independent prognostic information beyond clinical and histopathological risk factors ( p < 0.001), with an increase in concordance statistic from 0.82 to 0.86. The progression score showed high correlation ( R2 = 0.85) between paired fresh-frozen and formalin-fixed paraffin-embedded tumour specimens, supporting translation potential in the standard clinical setting. A limitation was the relatively low progression rate (5%, 37/750 patients). Conclusions The 12-gene progression score had independent prognostic power beyond clinical and histopathological risk factors, and may help in stratifying NMIBC patients to optimise treatment and follow-up regimens. Patient summary Clinical use of a 12-gene molecular test for disease aggressiveness may help in stratifying patients with non–muscle-invasive bladder cancer to optimal treatment regimens.
Abstract Background and purpose Adaptive radiotherapy (ART) using plan selection is being introduced clinically for bladder cancer, but the challenge of how to compensate for intra-fractional motion ...remains. The purpose of this study was to assess target coverage with respect to intra-fractional motion and the potential for normal tissue sparing in MRI-guided ART (MRIGART) using isotropic (MRIGARTiso), an-isotropic (MRIGARTanIso) and population-based margins (MRIGARTpop). Materials and methods Nine bladder cancer patients treated in a phase II trial of plan selection underwent 6–7 weekly repeat MRI series, each with volumetric scans acquired over a 10 min period. Adaptive re-planning on the 0 min MRI scans was performed using density override, simulating a hypo-fractionated schedule. Target coverage was evaluated on the 10 min scan to quantify the impact of intra-fractional motion. Results MRIGARTanIso reduced the course-averaged PTV by median 304 cc compared to plan selection. Bladder shifts affected target coverage in individual fractions for all strategies. Two patients had a v 95% of the bladder below 98% for MRIGARTiso. MRIGARTiso decreased the bowel V 25 with 15–46 cc compared to MRIGARTpop. Conclusion Online re-optimised ART has a considerable normal tissue sparing potential. MRIGART with online corrections for target shift during a treatment fraction should be considered in ART for bladder cancer.
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