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Pembrolizumab has received approval in the UK as first-line monotherapy for recurrent and/or metastatic HNSCC (R/M HNSCC) following the results of the KEYNOTE-048 trial, which demonstrated a longer overall survival (OS) in comparison to the EXTREME chemotherapy regimen in patients with a combined positive score (CPS) ≥1. In this article, we provide retrospective real-world data on the role of pembrolizumab monotherapy as first-line systemic therapy for HNSCC across 18 centers in the UK from March 20, 2020 to May 31, 2021. 211 patients were included, and in the efficacy analysis, the objective response rate (ORR) was 24.7%, the median progression-free survival (PFS) was 4.8 months (95% confidence interval [CI]: 3.6-6.1), and the median OS was 10.8 months (95% CI 9.0-12.5). Pembrolizumab monotherapy was well tolerated, with 18 patients having to stop treatment owing to immune-related adverse events (irAEs). 53 patients proceeded to second-line treatment with a median PFS2 of 10.2 months (95% CI: 8.8-11.5). Moreover, patients with documented irAEs had a statistically significant longer median PFS (11.3 vs. 3.3 months; log-rank p value = <.001) and median OS (18.8 vs. 8.9 months; log-rank p value <.001). The efficacy and safety of pembrolizumab first-line monotherapy for HNSCC has been validated using real-world data.
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Anticorpos Monoclonais Humanizados , Neoplasias de Cabeça e Pescoço , Carcinoma de Células Escamosas de Cabeça e Pescoço , Humanos , Anticorpos Monoclonais Humanizados/uso terapêutico , Anticorpos Monoclonais Humanizados/efeitos adversos , Masculino , Feminino , Carcinoma de Células Escamosas de Cabeça e Pescoço/tratamento farmacológico , Carcinoma de Células Escamosas de Cabeça e Pescoço/mortalidade , Pessoa de Meia-Idade , Idoso , Estudos Retrospectivos , Reino Unido/epidemiologia , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/patologia , Neoplasias de Cabeça e Pescoço/mortalidade , Adulto , Idoso de 80 Anos ou mais , Antineoplásicos Imunológicos/uso terapêutico , Antineoplásicos Imunológicos/efeitos adversos , Intervalo Livre de ProgressãoRESUMO
BACKGROUND: Most newly diagnosed oropharyngeal and hypopharyngeal cancers are treated with chemoradiotherapy with curative intent but at the consequence of adverse effects on quality of life. We aimed to investigate if dysphagia-optimised intensity-modulated radiotherapy (DO-IMRT) reduced radiation dose to the dysphagia and aspiration related structures and improved swallowing function compared with standard IMRT. METHODS: DARS was a parallel-group, phase 3, multicentre, randomised, controlled trial done in 22 radiotherapy centres in Ireland and the UK. Participants were aged 18 years and older, had T1-4, N0-3, M0 oropharyngeal or hypopharyngeal cancer, a WHO performance status of 0 or 1, and no pre-existing swallowing dysfunction. Participants were centrally randomly assigned (1:1) using a minimisation algorithm (balancing factors: centre, chemotherapy use, tumour type, American Joint Committee on Cancer tumour stage) to receive DO-IMRT or standard IMRT. Participants and speech language therapists were masked to treatment allocation. Radiotherapy was given in 30 fractions over 6 weeks. Dose was 65 Gy to primary and nodal tumour and 54 Gy to remaining pharyngeal subsite and nodal areas at risk of microscopic disease. For DO-IMRT, the volume of the superior and middle pharyngeal constrictor muscle or inferior pharyngeal constrictor muscle lying outside the high-dose target volume had a mandatory 50 Gy mean dose constraint. The primary endpoint was MD Anderson Dysphagia Inventory (MDADI) composite score 12 months after radiotherapy, analysed in the modified intention-to-treat population that included only patients who completed a 12-month assessment; safety was assessed in all randomly assigned patients who received at least one fraction of radiotherapy. The study is registered with the ISRCTN registry, ISRCTN25458988, and is complete. FINDINGS: From June 24, 2016, to April 27, 2018, 118 patients were registered, 112 of whom were randomly assigned (56 to each treatment group). 22 (20%) participants were female and 90 (80%) were male; median age was 57 years (IQR 52-62). Median follow-up was 39·5 months (IQR 37·8-50·0). Patients in the DO-IMRT group had significantly higher MDADI composite scores at 12 months than patients in the standard IMRT group (mean score 77·7 [SD 16·1] vs 70·6 [17·3]; mean difference 7·2 [95% CI 0·4-13·9]; p=0·037). 25 serious adverse events (16 serious adverse events assessed as unrelated to study treatment [nine in the DO-IMRT group and seven in the standard IMRT group] and nine serious adverse reactions [two vs seven]) were reported in 23 patients. The most common grade 3-4 late adverse events were hearing impairment (nine [16%] of 55 in the DO-IMRT group vs seven [13%] of 55 in the standard IMRT group), dry mouth (three [5%] vs eight [15%]), and dysphagia (three [5%] vs eight [15%]). There were no treatment-related deaths. INTERPRETATION: Our findings suggest that DO-IMRT improves patient-reported swallowing function compared with standard IMRT. DO-IMRT should be considered a new standard of care for patients receiving radiotherapy for pharyngeal cancers. FUNDING: Cancer Research UK.
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Transtornos de Deglutição , Neoplasias de Cabeça e Pescoço , Radioterapia de Intensidade Modulada , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Radioterapia de Intensidade Modulada/efeitos adversos , Transtornos de Deglutição/etiologia , Qualidade de Vida , Neoplasias de Cabeça e Pescoço/radioterapia , Quimiorradioterapia/efeitos adversosRESUMO
PURPOSE: Outcomes in RAS-mutant metastatic colorectal cancer (mCRC) remain poor and patients have limited therapeutic options. Adavosertib is the first small-molecule inhibitor of WEE1 kinase. We hypothesized that aberrations in DNA replication seen in mCRC with both RAS and TP53 mutations would sensitize tumors to WEE1 inhibition. METHODS: Patients with newly diagnosed mCRC were registered into FOCUS4 and tested for TP53 and RAS mutations. Those with both mutations who were stable or responding after 16 weeks of chemotherapy were randomly assigned 2:1 between adavosertib and active monitoring (AM). Adavosertib (250 mg or 300 mg) was taken orally once on days 1-5 and days 8-12 of a 3-week cycle. The primary outcome was progression-free survival (PFS), with a target hazard ratio (HR) of 0.5 and 80% power with a one-sided 0.025 significance level. RESULTS: FOCUS4-C was conducted between April 2017 and Mar 2020 during which time 718 patients were registered; 247 (34%) were RAS/TP53-mutant. Sixty-nine patients were randomly assigned from 25 UK hospitals (adavosertib = 44; AM = 25). Adavosertib was associated with a PFS improvement over AM (median 3.61 v 1.87 months; HR = 0.35; 95% CI, 0.18 to 0.68; P = .0022). Overall survival (OS) was not improved with adavosertib versus AM (median 14.0 v 12.8 months; HR = 0.92; 95% CI, 0.44 to 1.94; P = .93). In prespecified subgroup analysis, adavosertib activity was greater in left-sided tumors (HR = 0.24; 95% CI, 0.11 to 0.51), versus right-sided (HR = 1.02; 95% CI, 0.41 to 2.56; interaction P = .043). Adavosertib was well-tolerated; grade 3 toxicities were diarrhea (9%), nausea (5%), and neutropenia (7%). CONCLUSION: In this phase II randomized trial, adavosertib improved PFS compared with AM and demonstrates potential as a well-tolerated therapy for RAS/TP53-mutant mCRC. Further testing is required in this sizable population of unmet need.
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Proteínas de Ciclo Celular/antagonistas & inibidores , Neoplasias Colorretais/tratamento farmacológico , Mutação , Proteínas Tirosina Quinases/antagonistas & inibidores , Pirazóis/uso terapêutico , Pirimidinonas/uso terapêutico , Proteína Supressora de Tumor p53/genética , Conduta Expectante/estatística & dados numéricos , Proteínas ras/genética , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Colorretais/genética , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Inibidores Enzimáticos/uso terapêutico , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Prognóstico , Qualidade de Vida , Taxa de SobrevidaRESUMO
BACKGROUND: The onset of the COVID-19 pandemic necessitated rapid changes to the practice of head and neck oncology in UK. There was a delay between the onset of the pandemic and the release of guidelines from cancer societies and networks, leading to a variable response of individual centres. This survey was conducted to assess the pre-Covid-19 pandemic standard of practice for head and neck oncology patients and the treatment modifications introduced during the first wave of the pandemic in UK. METHODOLOGY: The UK National Cancer Research Institute (NCRI) Head and Neck Clinical Studies Group initiated a multi-centre survey using questionnaire to investigate the effect on feeding tube practice, radiotherapy (RT) fractionation and volumes, use of chemotherapy in the neo-adjuvant, concurrent and palliative setting, the use of immunotherapy in the palliative setting, access to radiology and histopathology services, and availability of surgical procedures. RESULTS: 30 centres were approached across UK; 23 (76.7%) centres responded and were included in the survey. There were differences in the standard practices in feeding tube policy, RT dose and fractionation as well as concurrent chemotherapy use. 21 (91%) participating centres had at least one treatment modification. 15 (65%) centres initiated a change in radical RT; changing to either a hypofractionation or acceleration schedule. For post-operative RT 10 centres (43.5%) changed to a hypofractionation schedule. 12 (52.2%) centres stopped neo-adjuvant chemotherapy for all patients; 13 (56.5%) centres followed selective omission of chemotherapy in concurrent chemo-radiotherapy patients, 17 (73.9%) centres changed first-line chemotherapy treatment to pembrolizumab (following NHS England's interim guidance) and 8 (34.8%) centres stopped the treatment early or offered delays for patients that have been already on systemic treatment. The majority of centres did not have significant changes associated with surgery, radiology, histopathology and dental screening. CONCLUSION: There are variations in the standard of practice and treatment modifications for head and neck cancer patients during Covid-19 pandemic. A timely initiative is required to form a consensus on head and neck cancer management in the UK and other countries.
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Acinic cell carcinoma is a rare, typically indolent, neoplasm that arises in the salivary glands. Metastatic disease is uncommon, occurring in around 10% of cases. We report the case of a 46-year-old male in whom the first sign of disseminated disease was increased skin pigmentation due to paraneoplastic Cushing's syndrome. He underwent 3 cycles of chemotherapy with carboplatin and paclitaxel with no symptomatic improvement and a mixed response on imaging. There is no evidence that systemic therapy prolongs survival in metastatic acinic cell carcinoma, and we lack a consensus as to which treatment options are most beneficial. A summary of published evidence regarding choice of palliative chemotherapy regimens and response is discussed in relation to the case.
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Síndrome de ACTH Ectópico/etiologia , Carcinoma de Células Acinares/complicações , Síndrome de Cushing/etiologia , Neoplasias Parotídeas/complicações , Hormônio Adrenocorticotrópico/biossíntese , Carcinoma de Células Acinares/metabolismo , Carcinoma de Células Acinares/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Parotídeas/metabolismo , Neoplasias Parotídeas/patologiaRESUMO
BACKGROUND: The incidence of human papillomavirus (HPV)-positive oropharyngeal cancer, a disease affecting younger patients, is rapidly increasing. Cetuximab, an epidermal growth factor receptor inhibitor, has been proposed for treatment de-escalation in this setting to reduce the toxicity of standard cisplatin treatment, but no randomised evidence exists for the efficacy of this strategy. METHODS: We did an open-label randomised controlled phase 3 trial at 32 head and neck treatment centres in Ireland, the Netherlands, and the UK, in patients aged 18 years or older with HPV-positive low-risk oropharyngeal cancer (non-smokers or lifetime smokers with a smoking history of <10 pack-years). Eligible patients were randomly assigned (1:1) to receive, in addition to radiotherapy (70 Gy in 35 fractions), either intravenous cisplatin (100 mg/m2 on days 1, 22, and 43 of radiotherapy) or intravenous cetuximab (400 mg/m2 loading dose followed by seven weekly infusions of 250 mg/m2). The primary outcome was overall severe (grade 3-5) toxicity events at 24 months from the end of treatment. The primary outcome was assessed by intention-to-treat and per-protocol analyses. This trial is registered with the ISRCTN registry, number ISRCTN33522080. FINDINGS: Between Nov 12, 2012, and Oct 1, 2016, 334 patients were recruited (166 in the cisplatin group and 168 in the cetuximab group). Overall (acute and late) severe (grade 3-5) toxicity did not differ significantly between treatment groups at 24 months (mean number of events per patient 4·8 [95% CI 4·2-5·4] with cisplatin vs 4·8 [4·2-5·4] with cetuximab; p=0·98). At 24 months, overall all-grade toxicity did not differ significantly either (mean number of events per patient 29·2 [95% CI 27·3-31·0] with cisplatin vs 30·1 [28·3-31·9] with cetuximab; p=0·49). However, there was a significant difference between cisplatin and cetuximab in 2-year overall survival (97·5% vs 89·4%, hazard ratio 5·0 [95% CI 1·7-14·7]; p=0·001) and 2-year recurrence (6·0% vs 16·1%, 3·4 [1·6-7·2]; p=0·0007). INTERPRETATION: Compared with the standard cisplatin regimen, cetuximab showed no benefit in terms of reduced toxicity, but instead showed significant detriment in terms of tumour control. Cisplatin and radiotherapy should be used as the standard of care for HPV-positive low-risk patients who are able to tolerate cisplatin. FUNDING: Cancer Research UK.
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Antineoplásicos/uso terapêutico , Cetuximab/uso terapêutico , Cisplatino/uso terapêutico , Neoplasias Orofaríngeas/terapia , Carcinoma de Células Escamosas de Cabeça e Pescoço/terapia , Doença Aguda , Antineoplásicos/administração & dosagem , Antineoplásicos/efeitos adversos , Cetuximab/administração & dosagem , Cetuximab/efeitos adversos , Quimiorradioterapia/efeitos adversos , Quimiorradioterapia/métodos , Cisplatino/administração & dosagem , Cisplatino/efeitos adversos , Esquema de Medicação , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Neoplasias Orofaríngeas/patologia , Neoplasias Orofaríngeas/virologia , Infecções por Papillomavirus/complicações , Radioterapia de Intensidade Modulada/efeitos adversos , Radioterapia de Intensidade Modulada/métodos , Medição de Risco , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/virologia , Resultado do TratamentoRESUMO
PURPOSE: About 40-60% of patients treated with post-operative radiotherapy for parotid cancer experience ipsilateral sensorineural hearing loss. Intensity-modulated radiotherapy (IMRT) can reduce radiation dose to the cochlea. COSTAR, a phase III trial, investigated the role of cochlear-sparing IMRT (CS-IMRT) in reducing hearing loss. METHODS: Patients (pT1-4 N0-3 M0) were randomly assigned (1:1) to 3-dimensional conformal radiotherapy (3DCRT) or CS-IMRT by minimisation, balancing for centre and radiation dose of 60Gy or 65Gy in 30 daily fractions. The primary end-point was proportion of patients with sensorineural hearing loss in the ipsilateral cochlea of ≥10 dB bone conduction at 4000 Hz 12 months after radiotherapy compared using Fisher's exact test. Secondary end-points included hearing loss at 6 and 24 months, balance assessment, acute and late toxicity, patient-reported quality of life, time to recurrence and survival. RESULTS: From Aug 2008 to Feb 2013, 110 patients (54 3DCRT; 56 CS-IMRT) were enrolled from 22 UK centres. Median doses to the ipsilateral cochlea were 3DCRT: 56.2Gy and CS-IMRT: 35.7Gy (p < 0.0001). 67/110 (61%) patients were evaluable for the primary end-point; main reasons for non-evaluability were non-attendance at follow-up or incomplete audiology assessment. At 12 months, 14/36 (39%) 3DCRT and 11/31 (36%) CS-IMRT patients had ≥10 dB loss (p = 0.81). No statistically significant differences were observed in hearing loss at 6 or 24 months or in other secondary end-points including patient-reported hearing outcomes. CONCLUSION: CS-IMRT reduced the radiation dose below the accepted tolerance of the cochlea, but this did not lead to a reduction in the proportion of patients with clinically relevant hearing loss.
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Neoplasias Parotídeas/radioterapia , Radioterapia de Intensidade Modulada/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
INTRODUCTION: Non-gestational choriocarcinoma (NGCC) is an extremely rare cancer. We report a case presenting in extremis. CASE REPORT: A 39-year-old woman presented with type 1 respiratory failure with a 1-month history of breathlessness. Computed tomography (CT) revealed widespread metastatic disease involving the lungs, liver, pancreas, and breast. Serum ß-human chorionic gonadotropin was markedly raised. Over 72 h, she deteriorated and was started on high-flow nasal cannula to facilitate discussions and for comfort. Histology from a breast biopsy suggested a choriocarcinoma, and she was commenced on etoposide and cisplatin. Unfortunately she continued to deteriorate and died on day 11 of admission. Molecular genotyping received post-mortem confirmed non-gestational choriocarcinomatous differentiation within a high-grade tumour. DISCUSSION: NGCC carries a worse prognosis compared with gestational choriocarcinoma and is historically less chemosensitive. However, differentiation between these two diagnoses is challenging due to a lack of immuno-histochemical differences. The NGCC in this case was likely to have originated in the lung due to a 12-cm mass in the lingula, and extensive emphysema on CT. Primary pulmonary choriocarcinoma has a rapidly fatal course in the majority of patients. CONCLUSION: This is the only case to our knowledge of NGCC presenting in extremis, where an accurate diagnosis was not achieved pre-mortem. This also demonstrates the merit of non-invasive ventilation within palliation to facilitate communication and comfort.
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BACKGROUND: The use of prophylactic radiotherapy to prevent procedure-tract metastases (PTMs) in malignant pleural mesothelioma remains controversial, and clinical practice varies worldwide. We aimed to compare prophylactic radiotherapy with deferred radiotherapy (given only when a PTM developed) in a suitably powered trial. METHODS: We did a multicentre, open-label, phase 3, randomised controlled trial in 22 UK hospitals of patients with histocytologically proven mesothelioma who had undergone large-bore pleural interventions in the 35 days prior to recruitment. Eligible patients were randomised (1:1), using a computer-generated sequence, to receive immediate radiotherapy (21 Gy in three fractions within 42 days of the pleural intervention) or deferred radiotherapy (same dose given within 35 days of PTM diagnosis). Randomisation was minimised by histological subtype, surgical versus non-surgical procedure, and pleural procedure (indwelling pleural catheter vs other). The primary outcome was the incidence of PTM within 7 cm of the site of pleural intervention within 12 months from randomisation, assessed in the intention-to-treat population. This trial is registered with ISRCTN, number ISRCTN72767336. FINDINGS: Between Dec 23, 2011, and Aug 4, 2014, we randomised 203 patients to receive immediate radiotherapy (n=102) or deferred radiotherapy (n=101). The patients were well matched at baseline. No significant difference was seen in PTM incidence in the immediate and deferred radiotherapy groups (nine [9%] vs 16 [16%]; odds ratio 0·51 [95% CI 0·19-1·32]; p=0·14). The only serious adverse event related to a PTM or radiotherapy was development of a painful PTM within the radiotherapy field that required hospital admission for symptom control in one patient who received immediate radiotherapy. Common adverse events of immediate radiotherapy were skin toxicity (grade 1 in 50 [54%] and grade 2 in four [4%] of 92 patients vs grade 1 in three [60%] and grade 2 in two [40%] of five patients in the deferred radiotherapy group who received radiotherapy for a PTM) and tiredness or lethargy (36 [39%] in the immediate radiotherapy group vs two [40%] in the deferred radiotherapy group) within 3 months of receiving radiotherapy. INTERPRETATION: Routine use of prophylactic radiotherapy in all patients with mesothelioma after large-bore thoracic interventions is not justified. FUNDING: Research for Patient Benefit Programme from the UK National Institute for Health Research.
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Neoplasias Pulmonares/cirurgia , Mesotelioma/cirurgia , Segunda Neoplasia Primária/prevenção & controle , Neoplasias Pleurais/cirurgia , Complicações Pós-Operatórias/radioterapia , Idoso , Feminino , Seguimentos , Humanos , Neoplasias Pulmonares/radioterapia , Neoplasias Pulmonares/secundário , Masculino , Mesotelioma/radioterapia , Mesotelioma/secundário , Mesotelioma Maligno , Estadiamento de Neoplasias , Segunda Neoplasia Primária/radioterapia , Dor/prevenção & controle , Neoplasias Pleurais/patologia , Neoplasias Pleurais/radioterapia , Prognóstico , Qualidade de Vida , Radioterapia Adjuvante , Projetos de Pesquisa , Taxa de SobrevidaRESUMO
INTRODUCTION: Patients with malignant pleural mesothelioma (MPM) may develop painful 'procedure tract metastasis' (PTM) at the site of previous pleural interventions. Prophylactic radiotherapy has been used to minimise this complication; however, three small randomised trials have shown conflicting results regarding its effectiveness. The surgical and large bore procedures in malignant pleural mesothelioma and radiotherapy trial (SMART Trial) is a suitably powered, multicentre, randomised controlled trial, designed to evaluate the efficacy of prophylactic radiotherapy within 42â days of pleural instrumentation in preventing the development of PTM in MPM. METHODS AND ANALYSIS: 203 patients with a histocytologically proven diagnosis of MPM, who have undergone a large bore pleural intervention (thoracic surgery, large bore chest drain, indwelling pleural catheter or local anaesthetic thoracoscopy) in the previous 35â days, will be recruited from UK hospitals. Patients will be randomised (1:1) to receive immediate radiotherapy (21â Gy in 3 fractions over 3 working days within 42â days of the pleural intervention) or deferred radiotherapy (21â Gy in 3 fractions over 3 working days given if a PTM develops). Patients will be followed up for 12â months. The primary outcome measure is the rate of PTM until death or 12â months (whichever is sooner), as defined by the presence of a clinically palpable nodule of at least 1â cm diameter felt within 7â cm of the margins of the procedure site as confirmed by two assessors. Secondary outcome measures include chest pain, quality of life, analgaesic requirements, healthcare utilisation and safety (including radiotherapy toxicity). ETHICS AND DISSEMINATION: The trial has received ethical approval from the Southampton B Research Ethics Committee (11/SC/0408). There is a Trial Steering Committee, including independent members and a patient and public representative. The trial results will be published in a peer-reviewed journal and presented at international conferences. TRIAL REGISTRATION NUMBER: ISRCTN72767336.
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Neoplasias Pulmonares/terapia , Mesotelioma/terapia , Inoculação de Neoplasia , Segunda Neoplasia Primária/prevenção & controle , Neoplasias Pleurais/terapia , Adulto , Protocolos Clínicos , Humanos , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/radioterapia , Neoplasias Pulmonares/cirurgia , Mesotelioma/patologia , Mesotelioma/radioterapia , Mesotelioma/cirurgia , Mesotelioma Maligno , Neoplasias Pleurais/patologia , Neoplasias Pleurais/radioterapia , Neoplasias Pleurais/cirurgia , Radioterapia Adjuvante , Projetos de PesquisaRESUMO
INTRODUCTION: To compare clinical and CT techniques in localisation of the tumour bed in patients undergoing adjuvant breast radiotherapy for breast cancer. METHODS: Patients were CT scanned in the treatment position following clinical delineation of the whole breast, surgical scar and boost volume. Computed tomography boost volumes were contoured in three dimensions. A definitive treatment plan was generated to encompass the CT-localised planning target volume (PTV) with ≥90% isodose using electrons. A hypothetical plan was also generated to cover the clinically determined boost field for comparison. The primary end point was the difference in PTV coverage by the 90% isodose between the plans based on clinically and CT localised boost volumes. RESULTS: The plans for 50 patients were evaluated. The median percentage of PTV encompassed by the 90% isodose using the clinical and CT techniques was 29% (range 5-90%) and 83% (range 25-100%), respectively. PTV coverage by the 90% isodose using the clinical technique was at least 10% less than that using CT technique in 88% of patients (95% confidence interval 77-95%; P < 0.0001). CONCLUSION: Tumour bed boost PTV coverage was insufficient using clinical determination as compared with CT localisation. This study supports CT planning for target volume localisation of the tumour bed boost in patients treated with breast-conserving therapy for breast cancer.