11C-methionine PET aids localization of microprolactinomas in patients with intolerance or resistance to dopamine agonist therapy.

PURPOSE: To assess the potential for 11C-methionine PET (Met-PET) coregistered with volumetric magnetic resonance imaging (Met-PET/MRCR) to inform clinical decision making in patients with poorly visualized or occult microprolactinomas and dopamine agonist intolerance or resistance. PATIENTS AND METHODS: Thirteen patients with pituitary microprolactinomas, and who were intolerant (n = 11) or resistant (n = 2) to dopamine agonist therapy, were referred to our specialist pituitary centre for Met-PET/MRCR between 2016 and 2020. All patients had persistent hyperprolactinemia and were being considered for surgical intervention, but standard clinical MRI had shown either no visible adenoma or equivocal appearances. RESULTS: In all 13 patients Met-PET/MRCR demonstrated a single focus of avid tracer uptake. This was localized either to the right or left side of the sella in 12 subjects. In one patient, who had previously undergone surgery for a left-sided adenoma, recurrent tumor was unexpectedly identified in the left cavernous sinus. Five patients underwent endoscopic transsphenoidal selective adenomectomy, with subsequent complete remission of hyperprolactinaemia and normalization of other pituitary function; three patients are awaiting surgery. In the patient with inoperable cavernous sinus disease PET-guided stereotactic radiosurgery (SRS) was performed with subsequent near-normalization of serum prolactin. Two patients elected for a further trial of medical therapy, while two declined surgery or radiotherapy and chose to remain off medical treatment. CONCLUSIONS: In patients with dopamine agonist intolerance or resistance, and indeterminate pituitary MRI, molecular (functional) imaging with Met-PET/MRCR can allow precise localization of a microprolactinoma to facilitate selective surgical adenomectomy or SRS.

Second surgery for progressive glioblastoma: a multi-centre questionnaire and cohort-based review of clinical decision-making and patient outcomes in current practice.

PURPOSE: Glioblastoma prognosis is poor. Treatment options are limited at progression. Surgery may benefit, but no quality guidelines exist to inform patient selection. We sought to describe variations in surgical management at progression, highlight where further evidence is needed, and build towards a consensus strategy. METHODS: Current practice in selection of patients with progressive GBM for second surgery was surveyed online amongst specialists in the UK and Europe. We complemented this with an assessment of practice in a retrospective cohort study from six United Kingdom neurosurgical units. We used descriptive statistics to analyse the data. RESULTS: 234 questionnaire responses were received. Maintaining or improving patient quality of life was key to decision making, with variation as to whether patient age, performance status or intended extent of resection was relevant. MGMT methylation status was not important. Half considered no minimum time after first surgery. 288 patients were reported in the cohort analysis. Median time to second surgery from first surgery 390 days. Median overall survival 815 days, with no association between time to second surgery and time to death (p = 0.874). CONCLUSIONS: This is the most wide-ranging examination of contemporaneous practice in management of GBM progression. Without evidence-based guidelines, the variation is unsurprising. We propose consensus guidelines for consideration, to reduce heterogeneity in decision making, support data collection and analysis of factors influencing outcomes, and to inform clinical trials to establish whether second surgery improves patient outcomes, or simply selects to patients already performing well.

Tumour Volume and Dose Influence Outcome after Surgery and High-dose Photon Radiotherapy for Chordoma and Chondrosarcoma of the Skull Base and Spine.

AIMS: To evaluate the long-term outcomes of patients with chordoma and low-grade chondrosarcoma after surgery and high-dose radiotherapy. MATERIALS AND METHODS: High-dose photon radiotherapy was delivered to 28 patients at the Neuro-oncology Unit at Addenbrooke's Hospital (Cambridge, UK) between 1996 and 2016. Twenty-four patients were treated with curative intent, 17 with chordoma, seven with low-grade chondrosarcoma, with a median dose of 65 Gy (range 65-70 Gy). Local control and survival rates were calculated using the Kaplan-Meier method. RESULTS: The median follow-up was 83 months (range 7-205 months). The 5 year disease-specific survival for chordoma patients treated with radical intent was 85%; the local control rate was 74%. The 5 year disease-specific survival for chondrosarcoma patients treated with radical intent was 100%; the local control rate was 83%. The mean planning target volume (PTV) was 274.6 ml (median 124.7 ml). A PTV of 110 ml or less was a good predictor of local control, with 100% sensitivity and 63% specificity. For patients treated with radical intent, this threshold of 110 ml or less for the PTV revealed a statistically significant difference when comparing local control with disease recurrence (P = 0.019, Fisher's exact test). Our data also suggest that the probability of disease control may be partly related to both target volume and radiotherapy dose. CONCLUSION: Our results show that refined high-dose photon radiotherapy, following tumour resection by a specialist surgical team, is effective in the long-term control of chordoma and low-grade chondrosarcoma, even in the presence of metal reconstruction. The results presented here will provide a useful source for comparison between high-dose photon therapy and proton beam therapy in a UK setting, in order to establish best practice for the management of chordoma and low-grade chondrosarcoma.

Automatic contour propagation using deformable image registration to determine delivered dose to spinal cord in head-and-neck cancer radiotherapy.

To determine delivered dose to the spinal cord, a technique has been developed to propagate manual contours from kilovoltage computed-tomography (kVCT) scans for treatment planning to megavoltage computed-tomography (MVCT) guidance scans. The technique uses the Elastix software to perform intensity-based deformable image registration of each kVCT scan to the associated MVCT scans. The registration transform is then applied to contours of the spinal cord drawn manually on the kVCT scan, to obtain contour positions on the MVCT scans. Different registration strategies have been investigated, with performance evaluated by comparing the resulting auto-contours with manual contours, drawn by oncologists. The comparison metrics include the conformity index (CI), and the distance between centres (DBC). With optimised registration, auto-contours generally agree well with manual contours. Considering all 30 MVCT scans for each of three patients, the median CI is [Formula: see text], and the median DBC is ([Formula: see text]) mm. An intra-observer comparison for the same scans gives a median CI of [Formula: see text] and a DBC of ([Formula: see text]) mm. Good levels of conformity are also obtained when auto-contours are compared with manual contours from one observer for a single MVCT scan for each of 30 patients, and when they are compared with manual contours from six observers for two MVCT scans for each of three patients. Using the auto-contours to estimate organ position at treatment time, a preliminary study of 33 patients who underwent radiotherapy for head-and-neck cancers indicates good agreement between planned and delivered dose to the spinal cord.

Highly Conformal Craniospinal Radiotherapy Techniques Can Underdose the Cranial Clinical Target Volume if Leptomeningeal Extension through Skull Base Exit Foramina is not Contoured.

AIMS: Craniospinal irradiation (CSI) remains a crucial treatment for patients with medulloblastoma. There is uncertainty about how to manage meningeal surfaces and cerebrospinal fluid (CSF) that follows cranial nerves exiting skull base foramina. The purpose of this study was to assess plan quality and dose coverage of posterior cranial fossa foramina with both photon and proton therapy. MATERIALS AND METHODS: We analysed the radiotherapy plans of seven patients treated with CSI for medulloblastoma and primitive neuro-ectodermal tumours and three with ependymoma (total n = 10). Four had been treated with a field-based technique and six with TomoTherapy™. The internal acoustic meatus (IAM), jugular foramen (JF) and hypoglossal canal (HC) were contoured and added to the original treatment clinical target volume (Plan_CTV) to create a Test_CTV. This was grown to a test planning target volume (Test_PTV) for comparison with a Plan_PTV. Using Plan_CTV and Plan_PTV, proton plans were generated for all 10 cases. The following dosimetry data were recorded: conformity (dice similarity coefficient) and homogeneity index (D2 - D98/D50) as well as median and maximum dose (D2%) to Plan_PTV, V95% and minimum dose (D99.9%) to Plan_CTV and Test_CTV and Plan_PTV and Test_PTV, V95% and minimum dose (D98%) to foramina PTVs. RESULTS: Proton and TomoTherapy™ plans were more conformal (0.87, 0.86) and homogeneous (0.07, 0.04) than field-photon plans (0.79, 0.17). However, field-photon plans covered the IAM, JF and HC PTVs better than proton plans (P = 0.002, 0.004, 0.003, respectively). TomoTherapy™ plans covered the IAM and JF better than proton plans (P = 0.000, 0.002, respectively) but the result for the HC was not significant. Adding foramen CTVs/PTVs made no difference for field plans. The mean Dmin dropped 3.4% from Plan_PTV to Test_PTV for TomoTherapy™ (not significant) and 14.8% for protons (P = 0.001). CONCLUSIONS: Highly conformal CSI techniques may underdose meninges and CSF in the dural reflections of posterior fossa cranial nerves unless these structures are specifically included in the CTV.

Tumour progression or pseudoprogression? A review of post-treatment radiological appearances of glioblastoma.

Glioblastoma (GBM) is a common brain tumour in adults, which, despite multimodality treatment, has a poor median survival. Efficacy of therapy is assessed by clinical examination and magnetic resonance imaging (MRI) features. There is now a recognised subset of treated patients with imaging features that indicate "progressive disease" according to Macdonald's criteria, but subsequently, show stabilisation or resolution without a change in treatment. In these cases of "pseudoprogression", it is believed that non-tumoural causes lead to increased contrast enhancement and conventional MRI is inadequate in distinguishing this from true tumour progression. Incorrect diagnosis is important, as failure to identify pseudoprogression could lead to an inappropriate change of effective therapy. The purpose of this review is to outline the current research into radiological assessment with MRI and molecular imaging of post-treatment GBMs, specifically the differentiation between pseudoprogression and tumour progression.

Clinical and practical considerations for the use of intensity-modulated radiotherapy and image guidance in neuro-oncology.

Intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy offer significant opportunities to improve outcomes for our patients, although they are not yet as widely used as they might be. IMRT allows better target coverage and lower organ at risk doses than conformal therapy. It also allows inhomogeneous dose plans to be developed, where these can provide benefit, either to dose escalate the tumour or reduce dose to adjacent or overlapping organs at risk. Image guidance adds precision and the possibility of careful reduction in planning target volume margins. The technologies can be valuable both for patients with highly malignant tumours, such as glioblastoma, and those with less malignant or benign tumours. In glioblastoma, temozolomide chemotherapy and surgical developments have improved survival, and developments in radiotherapy techniques should also be used to optimise outcome. Target volume delineation, including calculation of the planning target volume margin is critical. Clear definitions of the gross tumour and clinical target volumes are essential, following established guidelines. Normal tissue volume delineation is also essential for IMRT. The planning organ at risk volume has become a valuable tool to manipulate dose away from organs at risk to avoid toxicities. This is distinct from 'optimising volumes' used to drive the computer optimiser during planning. Hard data on central nervous system (CNS) normal tissue tolerance is surprisingly slight, reflecting the clinical imperative to avoid serious complications in neurological tissues. The effect of chemotherapy on radiotherapy tolerance in the CNS remains obscure, and more needs to be done to develop the knowledge base. IMRT provides better conformation of the high dose treatment to the shape of the target, and reduces the dose to normal tissue structures. Image guidance improves the accuracy of dose delivery, which is particularly important where steep dose gradients are present. These technologies should be regarded as the state-of-the-art for our CNS patients.

Current and investigational drug strategies for glioblastoma.

Medical treatments for glioblastoma face several challenges. Lipophilic alkylators remain the mainstay of treatment, emphasising the primacy of good blood-brain barrier penetration. Temozolomide has emerged as a major contributor to improved patient survival. The roles of procarbazine and vincristine in the procarbazine, lomustine and vincristine (PCV) schedule have attracted scrutiny and several lines of evidence now support the use of lomustine as effective single-agent therapy. Bevacizumab has had a convoluted development history, but clearly now has no major role in first-line treatment, and may even be detrimental to quality of life in this setting. In later disease, clinically meaningful benefits are achievable in some patients, but more impressively the combination of bevacizumab and lomustine shows early promise. Over the last decade, investigational strategies in glioblastoma have largely subscribed to the targeted kinase inhibitor paradigm and have mostly failed. Low prevalence dominant driver lesions such as the FGFR-TACC fusion may represent a niche role for this agent class. Immunological, metabolic and radiosensitising approaches are being pursued and offer more generalised efficacy. Finally, trial design is a crucial consideration. Progress in clinical glioblastoma research would be greatly facilitated by improved methodologies incorporating: (i) routine pharmacokinetic and pharmacodynamic assessments by preoperative dosing; and (ii) multi-stage, multi-arm protocols incorporating new therapy approaches and high-resolution biology in order to guide necessary improvements in science.

The value of image-guided intensity-modulated radiotherapy in challenging clinical settings.

OBJECTIVE: To illustrate the wider potential scope of image-guided intensity-modulated radiotherapy (IG-IMRT), outside of the "standard" indications for IMRT. METHODS: Nine challenging clinical cases were selected. All were treated with radical intent, although it was accepted that in several of the cases the probability of cure was low. IMRT alone was not adequate owing to the close proximity of the target to organs at risk, the risk of geographical miss, or the need to tighten planning margins, making image-guided radiotherapy an essential integral part of the treatment. Discrepancies between the initial planning scan and the daily on-treatment megavoltage CT were recorded for each case. The three-dimensional displacement was compared with the margin used to create the planning target volume (PTV). RESULTS: All but one patient achieved local control. Three patients developed metastatic disease but benefited from good local palliation; two have since died. A further patient died of an unrelated condition. Four patients are alive and well. Toxicity was low in all cases. Without daily image guidance, the PTV margin would have been insufficient to ensure complete coverage in 49% of fractions. It was inadequate by >3 mm in 19% of fractions, and by >5 mm in 9%. CONCLUSION: IG-IMRT ensures accurate dose delivery to treat the target and avoid critical structures, acting as daily quality assurance for the delivery of complex IMRT plans. These patients could not have been adequately treated without image guidance. ADVANCES IN KNOWLEDGE: IG-IMRT can offer improved outcomes in less common clinical situations, where conventional techniques would provide suboptimal treatment.

Interobserver variation in clinical target volume and organs at risk segmentation in post-parotidectomy radiotherapy: can segmentation protocols help?

OBJECTIVE: A study of interobserver variation in the segmentation of the post-operative clinical target volume (CTV) and organs at risk (OARs) for parotid tumours was undertaken. The segmentation exercise was performed as a baseline, and repeated after 3 months using a segmentation protocol to assess whether CTV conformity improved. METHODS: Four head and neck oncologists independently segmented CTVs and OARs (contralateral parotid, spinal cord and brain stem) on CT data sets of five patients post parotidectomy. For each CTV or OAR delineation, total volume was calculated. The conformity level (CL) between different clinicians' outlines was measured using a validated outline analysis tool. The data for CTVs were re-analysed after using the cochlear sparing therapy and conventional radiation segmentation protocol. RESULTS: Significant differences in CTV morphology were observed at baseline, yielding a mean CL of 30% (range 25-39%). The CL improved after using the segmentation protocol with a mean CL of 54% (range 50-65%). For OARs, the mean CL was 60% (range 53-68%) for the contralateral parotid gland, 23% (range 13-27%) for the brain stem and 25% (range 22-31%) for the spinal cord. CONCLUSIONS: There was low conformity for CTVs and OARs between different clinicians. The CL for CTVs improved with use of a segmentation protocol, but the CLs remained lower than expected. This study supports the need for clear guidelines for segmentation of target and OARs to compare and interpret the results of head and neck cancer radiation studies.

Temozolomide responsiveness in aggressive corticotroph tumours: a case report and review of the literature.

Pituitary carcinoma occurs in ~0.2% of resected pituitary tumours and carries a poor prognosis (mean survival <4 years), with standard chemotherapy regimens showing limited efficacy. Recent evidence suggests that temozolomide (TMZ), an orally-active alkylating agent used principally in the management of glioblastoma, may also be effective in controlling aggressive/invasive pituitary adenomas/carcinomas. A low level of expression of the DNA-repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) predicts TMZ responsiveness in glioblastomas, and a similar correlation has been observed in the majority of aggressive pituitary adenomas/carcinomas reported to date. Here, we report a case of a silent pituitary corticotroph adenoma, which subsequently re-presented with Cushing's syndrome due to functioning hepatic metastases. The tumour exhibited low immunohistochemical MGMT expression in both primary (pituitary) and secondary (hepatic) lesions. Initial TMZ therapy (200 mg/m² for 5 days every 28 days-seven cycles) resulted in marked clinical, biochemical [>50% fall in adrenocorticotrophic hormone (ACTH)] and radiological [partial RECIST (response evaluation criteria in solid tumors) response] improvements. The patient then underwent bilateral adrenalectomy. However, despite reintroduction of TMZ therapy (further eight cycles) ACTH levels plateaued and no further radiological regression was observed. We review the existing literature reporting TMZ efficacy in pituitary corticotroph tumours, and highlight the pointers/lessons for treating aggressive pituitary neoplasia that can be drawn from experience of susceptibility and evolving resistance to TMZ therapy in glioblastoma. Possible strategies for mitigating resistance developing during TMZ treatment of pituitary adenomas/carcinomas are also considered.

The concepts, diagnosis and management of early imaging changes after therapy for glioblastomas.

Since postoperative radiotherapy plus concomitant temozolomide followed by adjuvant temozolomide has become standard treatment for glioblastoma, the phenomenon of early post-treatment enlargement of the imaged tumour volume, usually without clinical deterioration, has become widely recognised. The term pseudoprogression has been used to describe a poorly understood pathophysiological process. In this review, the pathophysiological concepts, relevance, diagnosis and management of patients with 'pseudoprogression' and 'pseudoresponse' are discussed. Guidelines are given with respect to radiological imaging modality, mode and frequency. Further biological and clinical insights into these phenomena require carefully designed prospective studies.

Deconvolution of astronomical images using SOR with adaptive relaxation.

We address the potential performance of the successive overrelaxation technique (SOR) in image deconvolution, focusing our attention on the restoration of astronomical images distorted by atmospheric turbulence. SOR is the classical Gauss-Seidel iteration, supplemented with relaxation. As indicated by earlier work, the convergence properties of SOR, and its ultimate performance in the deconvolution of blurred and noisy images, can be made competitive to other iterative techniques, including conjugate gradients, by a proper choice of the relaxation parameter. The question of how to choose the relaxation parameter, however, remained open, and in the practical work one had to rely on experimentation. In this paper, using constructive (rather than exact) arguments, we suggest a simple strategy for choosing the relaxation parameter and for updating its value in consecutive iterations to optimize the performance of the SOR algorithm (and its positivity-constrained version, +SOR) at finite iteration counts. We suggest an extension of the algorithm to the notoriously difficult problem of "blind" deconvolution, where both the true object and the point-spread function have to be recovered from the blurred image. We report the results of numerical inversions with artificial and real data, where the algorithm is compared with techniques based on conjugate gradients. In all of our experiments +SOR provides the highest quality results. In addition +SOR is found to be able to detect moderately small changes in the true object between separate data frames: an important quality for multi-frame blind deconvolution where stationarity of the object is a necesessity.

Implementation of neuro-oncology service reconfiguration in accordance with NICE guidance provides enhanced clinical care for patients with glioblastoma multiforme.

BACKGROUND: Brain tumours account for <2% of all primary neoplasms but are responsible for 7% of the years of life lost from cancer before age 70 years. The latest survival trends for patients with CNS malignancies have remained largely static. The objective of this study was to evaluate the change in practice as a result of implementing the Improving Outcomes Guidance from the UK National Institute for Health and Clinical Excellence (NICE). METHODS: Patients were identified from the local cancer registry and hospital databases. We compared time from diagnosis to treatment, proportion of patients discussed at multidisciplinary team (MDT) meetings, treatment received, length of inpatient stay and survival. Inpatient and imaging costs were also estimated. RESULTS: Service reconfiguration and implementation of NICE guidance resulted in significantly more patients being discussed by the MDT--increased from 66 to 87%, reduced emergency admission in favour of elective surgery, reduced median hospital stay from 8 to 4.5 days, increased use of post-operative MRI from 17 to 91% facilitating early discharge and treatment planning, and reduced cost of inpatient stay from £2096 in 2006 to £1316 in 2009. Patients treated with optimal surgery followed by radiotherapy with concomitant and adjuvant temozolomide achieved outcomes comparable to those reported in clinical trials: median overall survival 18 months (2-year survival 35%). CONCLUSIONS: Advancing the management of neuro-oncology patients by moving from an emergency-based system of patient referral and management to a more planned elective outpatient-based pattern of care improves patient experience and has the potential to deliver better outcomes and research opportunities.

Paracetamol in pregnancy and the risk of wheezing in offspring: a systematic review and meta-analysis.

BACKGROUND: There is evidence to suggest that the risk of asthma might be increased with exposure to paracetamol in the intrauterine environment, infancy, later childhood and adult life. OBJECTIVE: To review the evidence from studies investigating the association between paracetamol use in pregnancy and childhood asthma. METHODS: A systematic review and meta-analysis was undertaken of studies reporting the association between paracetamol use in pregnancy and subsequent asthma in childhood. The primary outcome variable was wheeze in the last 12 months. For tabulated raw data, not adjusted for confounders, random effects odds ratios (OR) were pooled by the inverse variance weighted method. RESULTS: There were six studies identified that were included in the meta-analysis. The age of children studied ranged from 30 to 84 months. The pooled random effects OR for the risk of current wheeze in the children of women who were exposed to any paracetamol during any stage of pregnancy was 1.21 (95% confidence interval 1.02-1.44). Features of the studies variably included an association with paracetamol use during all trimesters of pregnancy and an association with persistent asthma, severe asthma, and with atopy. CONCLUSION AND CLINICAL RELEVANCE: The use of paracetamol during pregnancy is associated with an increased risk of childhood asthma. More research is urgently required to determine the impact of paracetamol during pregnancy on the risk of wheezing in offspring so that appropriate public health recommendations can be made.

Effectiveness of the 2009 seasonal influenza vaccine against pandemic influenza A(H1N1)2009 in healthcare workers in New Zealand, June-August 2009.

There is uncertainty whether the 2009 seasonal influenza vaccination influences the risk of infection with the 2009 pandemic influenza A(H1N1) virus. This issue was investigated in 548 healthcare workers from Capital and Coast District Health Board, Wellington, New Zealand, presenting with influenza-like illness during the influenza pandemic between June and August 2009. All workers completed an assessment sheet and had a nasopharyngeal swab tested by real-time RT-PCR. The risk of pandemic influenza A(H1N1) infection associated with the 2009 seasonal inactivated trivalent influenza vaccine was determined by logistic regression, with adjustment for potential confounding variables. In 96 workers pandemic influenza A(H1N1) RNA was detected and 452 tested negative. The multivariate analysis did not show any effect of vaccination on PCR-confirmed influenza A(H1N1)2009 infection (odds ratio 1.2, 95% confidence interval 0.7­1.9, p=0.48). We conclude that 2009 seasonal influenza vaccination had no protective effect against influenza A(H1N1)2009 infection amongst healthcare workers. To protect against further waves of the current pandemic influenza or future pandemics in which the influenza virus is antigenically distinct from contemporary seasonal influenza viruses, it would be necessary to vaccinate with a specific pandemic influenza vaccine, or a seasonal influenza vaccine that includes the pandemic influenza serotype.

Tumour shrinkage and contour change during radiotherapy increase the dose to organs at risk but not the target volumes for head and neck cancer patients treated on the TomoTherapy HiArt™ system.

AIMS: To quantify the changes in contours of the target and organs at risk and the differences between planned and delivered doses to the target and organs at risk during the course of radiotherapy in head and neck cancer patients treated with intensity-modulated radiotherapy on the TomoTherapy HiArt™ system. MATERIALS AND METHODS: Five patients with squamous cell carcinoma of the head and neck treated with radical chemoradiotherapy using the TomoTherapy HiArt system were included in the study. The target volumes were treated to three different dose levels depending on the level of clinical risk for harbouring disease. Patient positions were assessed daily with megavoltage computed tomography (MVCT) and positional correction made before each treatment when necessary. MVCTs were superimposed on to the planning kilovoltage computed tomography images for each patient and target volumes and organ at risk volumes were re-outlined on MVCT images. Doses to clinical target volumes and organs at risk were recalculated to show the actual delivered doses. RESULTS: There was shrinkage in the volume of the parotid glands during treatment in all cases. The mean volume reduction in the ipsilateral parotid gland was more marked at 30.2%, compared with the contralateral parotid glands. However, the mean percentage dose per fraction increase was higher in the contralateral parotid glands at 24%, compared with the ipsilateral parotids. The calculated doses were higher than the planned doses in all CTV-54, CTV-60 and CTV-68, but the mean dose differences were modest, in the range 1.3-2.4%. CONCLUSIONS: We have shown that there were considerable changes in the volume and dose to the parotids during treatment. The changes in volume and dose to the clinical target volume were more modest in comparison. Adaptive radiotherapy planning can be helpful in improving the dose to the parotid glands. However, its role in the optimisation of the dosage to the clinical target volume is less likely to result in a significant clinical benefit.

Residual postoperative tumour volume predicts outcome after high-dose radiotherapy for chordoma and chondrosarcoma of the skull base and spine.

AIMS: High-dose radiotherapy after surgical debulking is the treatment of choice for chordomas and chondrosarcomas. This study reviewed our outcomes, in relation to residual tumour volume and radiation dose, in order to inform our future practice. PATIENTS AND METHODS: Nineteen patients referred to the Neuro-Oncology Unit at Addenbrooke's Hospital (Cambridge, UK) between 1996 and 2009 and treated with photon radiotherapy were reviewed. Seventeen of the 19 were treated with curative intent. The median follow-up was 53 months. The tumours in the study had a mean gross tumour volume (GTV) of 17.2 cm(3) (median 10.5 cm(3)) and a range of 0-76.3 cm(3). The median dose was 65Gy in 39 fractions. RESULTS: The 5 year cause-specific survival for radically treated patients with chordomas was 92% and the 5 year local control rate was 83%. The 5 year cause-specific survival and local control rates with chondrosarcomas were both 100%. A planning target volume (PTV) below 90 cm(3) is predictive of local control, but volumes above this are not. The GTV seems to be a better predictor of outcome: among the 17 of 19 patients treated curatively, a GTV threshold of 30 cm(3) distinguished local failures from the 15 patients with local control, with sensitivity to detect local control of 100% (95% confidence interval 78-100%), specificity 100% (95% confidence interval 16-100%) and positive predictive value 100% (95% confidence interval 78-100%). CONCLUSIONS: Our results show a high level of efficacy for fractionated photon radiotherapy after surgery, in keeping with other series. In addition, we found that although surgical debulking is essential, a small residual tumour volume may still be controlled with high-dose photon radiotherapy. This information may be relevant during neurosurgical planning, possibly allowing a reduction in risk of serious neurological deficits. This should encourage the further development of sophisticated photon radiotherapy, for patients unsuitable for proton therapy.