Overgaard JHypoxic modification of radiotherapy in squamous cell carcinoma of the head and neck - a systematic review and meta-analysis. Radiother Oncol 100(1): 22-32
Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark. Radiotherapy and Oncology
(Impact Factor: 4.36).
04/2011; 100(1):22-32. DOI: 10.1016/j.radonc.2011.03.004
The importance of tumour hypoxia for the outcome of radiotherapy has been under investigation for decades. Numerous clinical trials modifying the hypoxic radioresistance in squamous cell carcinoma of the head and neck (HNSCC) have been conducted, but most have been inconclusive, partly due to a small number of patients in the individual trial. The present meta-analysis was, therefore, performed utilising the results from all clinical trials addressing the specific question of hypoxic modification in HNSCC undergoing curative intended primary radiotherapy alone.
A systematic review of published and unpublished data identified 4805 patients with HNSCC treated in 32 randomized clinical trials, applying, normobaric oxygen or carbogen breathing (5 trials); hyperbaric oxygen (HBO) (9 trials); hypoxic radiosensitizers (17 trials) and HBO and radiosensitizer (1 trial). The trials were analysed with regard to the following endpoints: loco-regional control (32 trials), disease specific survival (30 trials), overall survival (29 trials), distant metastases (12 trials) and complications to radiotherapy (23 trials).
Overall hypoxic modification of radiotherapy in head and neck cancer did result in a significant improved therapeutic benefit. This was most dominantly observed when using the direct endpoint of loco-regional control with an odds ratio (OR) of 0.71, 95% cf.l. 0.63-0.80; p<0.001), but this was almost mirrored in the disease specific survival (OR: 0.73, 95% cf.l. 0.64-0.82; p<0.001), and to a lesser extent in the overall survival (OR: 0.87, 95% cf.l. 0.77-0.98; p=0.03). The risk of distant metastases was not significantly influenced although it appears to be less in the tumours treated with hypoxic modification (OR: 0.87, 95% cf.l. 0.69-1.09; p=0.22), whereas the radiation related late complications were not influenced by the overall use of hypoxic modifications (OR: 1.00, 95% cf.l. 0.82-1.23; p=0.96). The improvement in loco-regional control was found to be independent of the type of hypoxic modification. The trials have used different fractionation schedules, including large doses per fraction, which may result in relatively more hypoxia and greater benefit. However, analysis of HNSCC trials using conventional fractionation only, showed that the significant effect of hypoxic modification was maintained.
The meta-analysis thus demonstrates that there is level 1a evidence in favour of adding hypoxic modification to radiotherapy of squamous cell carcinomas of the head and neck.
Available from: Loredana Marcu
- "Similar results were achieved by Zhou et al. in head and neck cancer patients, indicating a strong relationship between elevated Glut-1 levels and poor prognosis . However, the risk of distant metastases was shown to be lower in head and neck tumours treated with hypoxia modifiers . With today's technological advances, locoregional control of several types of cancers, including head and neck, has improved. "
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ABSTRACT: Hypoxia plays an important role in tumour recurrence among head and neck cancer patients. The identification and quantification of hypoxic regions are therefore an essential aspect of disease management. Several predictive assays for tumour oxygenation status have been developed in the past with varying degrees of success. To date, functional imaging techniques employing positron emission tomography (PET) have been shown to be an important tool for both pretreatment assessment and tumour response evaluation during therapy. Hypoxia-specific PET markers have been implemented in several clinics to quantify hypoxic tumour subvolumes for dose painting and personalized treatment planning and delivery. Several new radiotracers are under investigation. PET-derived functional parameters and tracer pharmacokinetics serve as valuable input data for computational models aiming at simulating or interpreting PET acquired data, for the purposes of input into treatment planning or radio/chemotherapy response prediction programs. The present paper aims to cover the current status of hypoxia imaging in head and neck cancer together with the justification for the need and the role of computer models based on PET parameters in understanding patient-specific tumour behaviour.
Available from: Shui-Hong Zhou
- "GLUT-1, a major protein of cellular glucose uptake, has been studied in NEC . Hypoxia promotes the chemo-radioresistance of carcinomas  and GLUT-1 is overexpressed in a hypoxic environment . HIF-1α, a transcription factor associated with the cellular response to hypoxia , upregulates the expression of several hypoxia response genes, including GLUT-1. "
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Small-cell neuroendocrine carcinoma (SCNEC) of the head and neck is rare. The prognosis of SCNEC in the nasal cavity and larynx is poor. The aim of this study was to investigate the clinicopathological features of nasal and laryngeal SCNEC and to determine the expression of HIF-1α, GLUT-1, PI3K, and p-Akt in SCNEC.
Between 2003 and 2012, 10 consecutive patients with histologically demonstrated nasal and laryngeal SCNEC were enrolled. Clinicopathological materials and follow-up data were analyzed retrospectively. Immunohistochemistry was used to detect GLUT-1, HIF-1α, PI3K, and p-Akt expression in paraffin wax-embedded tumor specimens.
The subjects were eight males and two females with a mean age of 60.8 (range: 53 to 71) years. Tumors were located in the maxillary sinus (n = 3) and larynx (n = 7). At last follow-up, four patients (40.0%) had local recurrence and five patients (50.0%) had developed distant metastases. Six patients died. The mean overall survival was 19.3 ± 2.1 months. Expression of GLUT-1, HIF-1α, PI3K, and p-Akt was seen in sinonasal and laryngeal SCNEC in 80 (8 out of 10), 50 (5 out of 10), 40 (4 out of 10), and 40% (4 out of 10) of cases, respectively. Expression of GLUT-1, HIF-1α, PI3K, and p-Akt was higher in sinonasal and laryngeal SCNEC than in precancerous lesions.
Primary sinonasal and laryngeal SCNEC is rare. This paper presents 10 cases of sinonasal and laryngeal SCNEC with more common local recurrence and distant metastasis. HIF-1α, GLUT-1, PI3K, and p-Akt expression was higher in sinonasal and laryngeal SCNEC than in precancerous lesions.
Available from: Ludwig Dubois
- "Low tumoral oxygen levels (hypoxia) are known to decrease the effectiveness of RT  , however, the precise mechanisms causing radioresistance are not yet completely understood  . RT causes DNA damage either by direct ionization or indirectly by DNA interaction of radicals formed by ionization of water surrounding DNA  resulting in DNA single-or double-strand breaks. "
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ABSTRACT: Radiotherapy is an important component of anti-cancer treatment. However, not all cancer patients respond to radiotherapy, and with current knowledge clinicians are unable to predict which patients are at high risk of recurrence after radiotherapy. There is therefore an urgent need for biomarkers to guide clinical decision-making. Although the importance of epigenetic alterations is widely accepted, their application as biomarkers in radiotherapy has not been studied extensively. In addition, it has been suggested that radiotherapy itself introduces epigenetic alterations. As epigenetic alterations can potentially be reversed by drug treatment, they are interesting candidate targets for anticancer therapy or radiotherapy sensitizers. The application of demethylating drugs or histone deacetylase inhibitors to sensitize patients for radiotherapy has been studied in vitro, in vivo as well as in clinical trials with promising results. This review describes the current knowledge on epigenetics in radiotherapy.
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