Cochlear pharmacokinetics of cisplatin: an in vivo study in the guinea pig

OBJECTIVES/HYPOTHESIS

Cisplatin produces toxic lesions to outer hair cells (OHCs) in the cochlear base but not in the apex. The objective of this study was to compare the pharmacokinetic profile of cisplatin in scala tympani (ST) perilymph in the cochlear base and apex, respectively.

STUDY DESIGN

In vivo animal study.

METHODS

Forty-seven guinea pigs were given an intravenous bolus injection of an ototoxic dose of cisplatin. Ten to 240 minutes after cisplatin was given, blood, cerebrospinal fluid (CSF), and ST perilymph were aspirated within the same target time. ST perilymph was aspirated from the basal turn and from the apex of the cochlea by two different sampling techniques. Liquid chromatography with postcolumn derivatization was used for quantitative determination of the parent drug.

RESULTS

Ten minutes after administration, the concentration of cisplatin in ST perilymph was 4-fold higher in the basal turn of the cochlea than in the apex. At 30 minutes, the drug concentrations did not differ. At 60 minutes, the level of cisplatin in ST perilymph and blood UF was equivalent. The perilymph-blood ratio increased thereafter with time.

CONCLUSION

The pharmacokinetic findings of an early high concentration of cisplatin in the base of the cochlea and delayed elimination of cisplatin from ST perilymph compared to blood might correlate to the cisplatin-induced loss of OHCs in the base of the cochlea.

MRI evidence of endolymphatic impermeability to the gadolinium molecule in the in vivo mouse inner ear at 9.4 tesla

OBJECTIVE

Previous in vivo experimental magnetic resonance imaging (MRI) investigations of the mammalian inner ear at 4.7 Tesla have indicated that intravenously injected gadolinium (Gd) penetrates the perilymphatic labyrinth, but not the endolymphatic membranous labyrinth. In the present study, high field MRI at 9.4T was used to visualize the in vivo mouse vestibulo-cochlea system, and to determine whether the endolymphatic system is permeable to a Gd complex.

METHODS

A 9.4 T Varian magnet equipped with a 12 cm inner diameter gradient system with maximum gradient strength of 600 mT/m, a millipede coil (Varian design) and a Gd contrast agent were used for image acquisition in the normal C57 BL-6 mouse.

RESULTS

High-resolution 2D and 3D images of the mouse cochlea were acquired within 80 minutes following intravenous injection of Gd. Gd initially permeated the perilymphatic scala tympani and scala vestibuli, and permitted visualization of both cochlear turns from base to apex. The superior, inferior and lateral semicircular canals were subsequently visualized in 3 planes. The membranous endolymphatic labyrinth was impermeable to intravenously injected Gd, and thus showed no apparent uptake of Gd at 9.4T.

CONCLUSION

The 9.4T field strength MRI permitted acquisition of high resolution images of anatomical and physiological features of the normal, wild type mouse perilymphatic inner ear in vivo, and provided further evidence that the endolymphatic system is impermeable to intravenously injected Gd.

Evaluation of human papillomavirus antibodies and risk of subsequent head and neck cancer

PURPOSE

Human papillomavirus type 16 (HPV16) infection is causing an increasing number of oropharyngeal cancers in the United States and Europe. The aim of our study was to investigate whether HPV antibodies are associated with head and neck cancer risk when measured in prediagnostic sera.

METHODS

We identified 638 participants with incident head and neck cancers (patients; 180 oral cancers, 135 oropharynx cancers, and 247 hypopharynx/larynx cancers) and 300 patients with esophageal cancers as well as 1,599 comparable controls from within the European Prospective Investigation Into Cancer and Nutrition cohort. Prediagnostic plasma samples from patients (collected, on average, 6 years before diagnosis) and control participants were analyzed for antibodies against multiple proteins of HPV16 as well as HPV6, HPV11, HPV18, HPV31, HPV33, HPV45, and HPV52. Odds ratios (ORs) of cancer and 95% CIs were calculated, adjusting for potential confounders. All-cause mortality was evaluated among patients using Cox proportional hazards regression.

RESULTS

HPV16 E6 seropositivity was present in prediagnostic samples for 34.8% of patients with oropharyngeal cancer and 0.6% of controls (OR, 274; 95% CI, 110 to 681) but was not associated with other cancer sites. The increased risk of oropharyngeal cancer among HPV16 E6 seropositive participants was independent of time between blood collection and diagnosis and was observed more than 10 years before diagnosis. The all-cause mortality ratio among patients with oropharyngeal cancer was 0.30 (95% CI, 0.13 to 0.67), for patients who were HPV16 E6 seropositive compared with seronegative.

CONCLUSION

HPV16 E6 seropositivity was present more than 10 years before diagnosis of oropharyngeal cancers.

Weight loss in patients with head and neck cancer during and after conventional and accelerated radiotherapy

Background

Weight loss is common among patients with squamous cell carcinoma of the head and neck (SCCHN) and is mainly due to tumor and treatment related factors. The aim of the present study was to evaluate weight loss in patients with SCCHN undergoing two different radiotherapy (RT) schedules.

Material and methods

Nutritional data were analyzed from the ARTSCAN study, a controlled randomized prospective Swedish multicenter study conducted with the aim of comparing conventional fractionation (2.0 Gy per day, total 68 Gy during 7 weeks) and accelerated fractionation (1.1 + 2.0 Gy per day, total 68 Gy during 4.5 weeks). Seven hundred and fifty patients were randomized and 712 patients were followed from the start of RT in the present nutritional study.

Results

The patients had a weight loss of 11.3% (± 8.6%) during the acute phase (start of RT up to five months after the termination of RT). No difference in weight loss was seen between the two RT fractionation schedules (p = 0.839). Three factors were significantly predictive for weight loss during the acute phase, i.e. tumor site, overweight/obesity or lack of tube feeding at the start of RT. Moreover, the nadir point of weight loss occurred at five months after the termination of RT.

Conclusion

The results of the present study showed no difference in weight loss between the two RT fractionation schedules and also highlight that weight loss in SCCHN is a multifactorial problem. Moreover, the nadir of weight loss occurred at five months after the termination of treatment which calls for more intense nutritional interventions during the period after treatment.

High expression of p63 is correlated to poor prognosis in squamous cell carcinoma of the tongue

BACKGROUND

p63 proteins are important in formation of the oral mucosa. Normal oral mucosa shows a balance between the six protein isoforms, whereas an imbalance between them is seen in squamous cell carcinomas (SCC). There is controversy over the clinical impact of p63 in SCC, which may relate to different expression in different areas. In addition, p63 isoforms can act as p53-like molecules (TAp63) or can inhibit p53 functions (ΔNp63) and expression of these isoforms varies in different tumours. Here, we chose to concentrate on the most common intra-oral sub-site, SCC of the mobile tongue.

METHODS

Total p63, ΔNp63 and TAp63 were analysed separately using immunohistochemistry. The percentage of cells and intensity of expression of different isoforms of p63 was evaluated using a quick score method and correlated with clinical data in a group of 87 patients with tongue SCC.

RESULTS

All tumours expressed p63 in at least 60% of the cells when using two different antibodies detecting all 6 isoforms. p63 expression correlated significantly with 2-year survival (P = 0.018), with fewer patients surviving 2 years if their tumours expressed p63 with strong intensity in at least 80% of the cells (quick score 18). Looking at 5-year survival, this was even more emphasized. ΔNp63 was expressed in all tumours, whereas expression of TAp63 was seen only in 59/87 patients, usually at very low levels.

CONCLUSIONS

Based on the present data, we recommend using expression of p63 as an additional factor contributing prognostic information in analysis of SCC in the tongue.

Subsite-based alterations in miR-21, miR-125b, and miR-203 in squamous cell carcinoma of the oral cavity and correlation to important target proteins

BACKGROUND

MicroRNAs (miRNAs) are small noncoding RNA molecules with an essential role in regulation of gene expression. miRNA expression profiles differ between tumor and normal control tissue in many types of cancers and miRNA profiling is seen as a promising field for finding new diagnostic and prognostic tools.

MATERIALS AND METHODS

In this study, we have analyzed expression of three miRNAs, miR-21, miR-125b, and miR-203, and their potential target proteins p53 and p63, known to be deregulated in squamous cell carcinoma of the head and neck (SCCHN), in two distinct and one mixed subsite in squamous cell carcinoma in the oral cavity.

RESULTS

We demonstrate that levels of miRNA differ between tumors of different subsites with tongue tumors showing significant deregulation of all three miRNAs, whereas gingival tumors only showed significant downregulation of miR-125b and the mixed group of tumors in tongue/floor of the mouth showed significant deregulation of miR-21 and miR-125b. In the whole group of oral squamous cell carcinoma (SCC), a significant negative correlation was seen between miR-125b and p53 as well as a significant correlation between TP53 mutation status and miR-125b.

CONCLUSION

The present data once again emphasize the need to take subsite into consideration when analyzing oral SCC and clearly show that data from in vitro studies cannot be transferred directly to the in vivo situation.

Effect of radiotherapy on expression of hyaluronan and EGFR and presence of mast cells in squamous cell carcinoma of the head and neck

Head and neck squamous cell carcinoma is a common form of cancer, and despite improvements in treatment during the last decades, survival rates have not significantly increased. There is therefore a need to better understand how these tumours and the adjacent tissues react to radiotherapy, the most common type of treatment for this group of tumours. In order to improve this understanding, the expression of hyaluronan (HA) and epidermal growth factor receptor (EGFR) and the presence of mast cells were mapped before and after radiotherapy using immunohistochemistry. The results showed HA and EGFR to have similar expression patterns in tumour tissue and histologically normal squamous epithelium prior to radiotherapy. Following radiotherapy, EGFR increased in histologically normal epithelium. An increased number of mast cells were also observed as a result of radiotherapy. No expression of EGFR was observed in the connective tissue either prior to or following radiotherapy.

Results from the Swedish Head and Neck Cancer Register for Oral Cancer

Objective: The Swedish Head and Neck Cancer Register (SweHNCR) started in 2008. The purpose was to register all new patients with head and neck cancer and collect data about tumor stage, planned and received treatment, relapse and survival. Data for oral cancer from the first 3 years will be presented.

Method: The SweHNCR is covering more than 95% of all HN cancers in Sweden. Between 2008 and 2010, 3701 new cases were registered including 1029 of oral cancers (28%). The most common location was tongue (42%), followed by gingival (21%), buccal mucosa (19%), floor of the mouth (14%), and hard palate (3%). Less than 10% were treated with palliative intent.

Results: Sixty percent of all gingival cancers were diagnosed as T4 while 70% of the tongue cancers were diagnosed as T1-T2. A total of 25% had lymphnode metastasis, range 27% (tongue) to 12% (hard palate). Surgery was the most common treatment (38%), followed by combinations of surgery and radiotherapy (36%), 19% were treated with radiotherapy alone or combined with chemotherapy, and 7% did not receive any treatment. The 2-year survival was 69% (hard palate 83%, buccal mucosa 74%, gingival 70%, tongue 69%, and floor of the mouth 63%). Data regarding treatment and stage of the disease will be further analyzed together with survival data.

Conclusion: Oral cancer is the most common HN cancer location in Sweden. Almost all patients are given curative treatment (90%) consisting of surgery alone or in combination with radiotherapy (70%). The 2-year survival rate varied between 63% to 83%. Different treatment policies and survival rate was found within the country.

Transcriptional profiling of formalin fixed paraffin embedded tissue: pitfalls and recommendations for identifying biologically relevant changes

Expression profiling techniques have been used to study the biology of many types of cancer but have been limited to some extent by the requirement for collection of fresh tissue. In contrast, formalin fixed paraffin embedded (FFPE) samples are widely available and represent a vast resource of potential material. The techniques used to handle the degraded and modified RNA from these samples are relatively new and all the pitfalls and limitations of this material for whole genome expression profiling are not yet clarified. Here, we analyzed 70 FFPE tongue carcinoma samples and 17 controls using the whole genome DASL array covering nearly 21000 genes. We identified that sample age is related to quality of extracted RNA and that sample quality influences apparent expression levels in a non-random manner related to gene probe sequence, leading to spurious results. However, by removing sub-standard samples and analysing only those 28 cancers and 15 controls that had similar quality we were able to generate a list of 934 genes significantly altered in tongue cancer compared to control samples of tongue. This list contained previously identified changes and was enriched for genes involved in many cancer-related processes such as tissue remodelling, inflammation, differentiation and apoptosis. Four novel genes of potential importance in tongue cancer development and maintenance, SH3BGL2, SLC2A6, SLC16A3 and CXCL10, were independently confirmed, validating our data. Hence, gene expression profiling can be performed usefully on archival material if appropriate quality assurance steps are taken to ensure sample consistency and we present some recommendations for the use of FFPE material based on our findings.

Radiological imaging of the neck for initial decision-making in oral squamous cell carcinomas--a questionnaire survey in the Nordic countries

BACKGROUND

Fast and accurate work-up is crucial to ensure the best possible treatment and prognosis for patients with head and neck cancer. The presence or absence of neck lymph node metastases is important for the prognosis and the choice of treatment. Clinical lymph node (N)-staging is done by palpation and diagnostic imaging of the neck. We investigated the current practice of the initial radiological work-up of patients with oral squamous cell carcinomas (OSCC) in the Nordic countries.

METHODS

A questionnaire regarding the availability and use of guidelines and imaging modalities for radiological N-staging in OSCC was distributed to 21 Head and Neck centres in Denmark (n = 4), Finland (n = 5), Iceland (n = 1), Norway (n = 4) and Sweden (n = 7). We also asked for a description of the radiological criteria for determining the lymph nodes as clinical positive (cN+) or negative (cN0).

RESULTS

All 21 Head and Neck centres responded to the questionnaire. Denmark and Finland have national guidelines, while Norway and Sweden have local or regional guidelines. Seventeen of the 19 centres with available guidelines recommended computed tomography (CT) of the cN0 neck. The waiting time may influence the imaging modalities used. Lymph node size was the most commonly used criteria for radiological cN+, but the cut-off measures vary from 0.8 to 2.0 cm.

CONCLUSION

Overall, CT is the most commonly recommended and used imaging modality for OSCC. Despite availability of national guidelines the type and number of radiological examinations vary between centres within a country, but the implementation of a fast-track programme may facilitate fast access to imaging. The absence of uniform criteria for determining the lymph nodes of the neck as cN+ complicates the comparison of the accuracy of the imaging modalities. Well-defined radiological strategies and criteria are needed to optimise the radiological work-up in OSCC.

The importance of stromal inflammation in squamous cell carcinoma of the tongue

BACKGROUND

Histological risk assessment evaluating worst pattern of tumour invasion (WPOI), and lymphocytic response (LR), has previously been shown to be of prognostic significance in squamous cell carcinomas of the head and neck (SCCHN). SCCHN is a heterogeneous group of tumours including tumours located in the oral cavity, of which the majority is located in the tongue.

METHODS

Haematoxylin/eosin-stained slides from diagnostic biopsies from 94 cases of SCC on the tongue were evaluated for WPOI and LR. Within the inflammatory infiltrate, the percentage of eosinophilic granulocytes was also estimated. Results were correlated with clinical data such as response to treatment and recurrence.

RESULTS

For WPOI the majority of patients, 84%, showed small invasive tumours islands with a size <15 cells (grade 4). No correlation with survival, response to treatment or recurrence was seen for WPOI. More than half of the patients showed a dense lymphocytic infiltrate, a factor that was significantly correlated with complete response to radio therapy. Of the patients with dense lymphoid infiltrate, the majority, 63%, did not either have a recurrence. No significant correlation with recurrence, response to treatment or any other factor was seen for presence of eosinophils.

CONCLUSIONS

Data clearly showed that tongue tumours have a split invasive growth pattern and an intense inflammatory response at the tumour interface. Results also indicated that evaluation of the intensity of the inflammatory infiltrate at the tumour interface in tongue SCC could provide information of potential importance for choice of treatment and prognosis.

Dose-dependent protection on cisplatin-induced ototoxicity - an electrophysiological study on the effect of three antioxidants in the Sprague-Dawley rat animal model

BACKGROUND

Sprague-Dawley rats were used as an acute cisplatin ototoxicity model to compare the chemo-protective efficacy of 2 sulphur-containing antioxidants (D-methionine, N-L-acetylcysteine) and 1 seleno-organic compound (ebselen). Each putative chemo-protective agent was tested at 3 different dosages in order to assess the influence of dose on auditory preservation.

MATERIAL/METHODS

A total of 40 Sprague-Dawley albino male rats were used in the study. Animals were divided into 10 groups, 3 groups of different doses for each protective agent and a cisplatin-treated control group. The animals were weight-matched before drug exposure to ensure similar weights in all groups. Auditory function was assessed with auditory brainstem responses and distortion product otoacoustic emissions at time zero and at 96 hours post-treatment.

RESULTS

At the post-treatment follow-up no significant threshold change at 8 kHz was found in the D-Met- and NAC-treated groups. All ebselen-treated animals presented significant threshold elevations. At 12 and 16 kHz, only the groups treated with 300, 450 mg/kg of D-Met and 475 mg/kg of NAC presented thresholds comparable to the pre-treatment ABR data. The ebselen-treated animals presented significant threshold shifts and showed the highest threshold elevations. The DPOAE data analysis showed that only the animals from the 350 mg/kg D-met group presented lack of statistical differences between the pre and post recordings.

CONCLUSIONS

Considering the outcome from the ABR and DPOAE analyses together, only the 350 mg/kg D-met group presented a complete auditory preservation against the 14 mg/kg cisplatin administered i.v. Data from ebselen pre-treated Sprague-Dawley albino male rats demonstrate that ebselen dosages up to 12 mg/kg given by i.p. administration lack auditory preservation in this species.

Differences in p63 expression in SCCHN tumours of different sub-sites within the oral cavity

Squamous cell carcinoma of the head and neck, SCCHN, the sixth most common cancer in the world, comprises tumours of different anatomical sites. The overall survival is low, and there are no good prognostic or predictive markers available. The p53 homologue, p63, plays an important role in development of epithelial structures and has also been suggested to be involved in development of SCCHN. However, most studies on p63 in SCCHN have not taken into account the fact that this group of tumours is heterogeneous in terms of the particular site of origin of the cancer. Mapping and comparing p63 expression levels in tumours and corresponding clinically normal tissue in SCCHN from gingiva, tongue and tongue/floor of the mouth revealed clear differences between these regions. In normal samples from tongue and gingiva, tongue samples showed 2.5-fold higher median p63 expression and also more widespread expression compared to gingival samples. These results emphasise the importance of taking sub-site within the oral cavity into consideration in analyses of SCCHN.

p63 Transcriptionally regulates BNC1, a Pol I and Pol II transcription factor that regulates ribosomal biogenesis and epithelial differentiation

The p53-family member, p63 is a transcription factor that influences cellular adhesion, motility, proliferation, survival and apoptosis, and has a major role in regulating epithelial stem cells. Expression of p63 is often dysregulated in squamous cell carcinomas of the head and neck. In this study we show that p63 induces the expression of the basal epithelial transcription factor, Basonuclin 1. Basonuclin 1 is an unusual transcription factor that interacts with a subset of promoters of genes that are transcribed by both RNA polymerase-I and -II and has roles in maintaining ribosomal biogenesis and the proliferative potential of immature epithelial cells. Chromatin immunoprecipitation and reporter assays demonstrate that Basonuclin 1 is a direct transcriptional target of p63 and we also show that up-regulation of Basonuclin 1 is a common event in squamous cell carcinomas of the head and neck. These data identify a new transcriptional programme mediated by p63 regulation of the Basonuclin 1 transcription factor in squamous cell carcinomas and provide a novel link of p63 with the regulation of ribosomal biogenesis in epithelial cancer.

Prevention of cisplatin-induced hearing loss by administration of a thiosulfate-containing gel to the middle ear in a guinea pig model

PURPOSE

Thiosulfate may reduce cisplatin-induced ototoxicity, most likely by relieving oxidative stress and by forming inactive platinum complexes. This study aimed to determine the concentration and protective effect of thiosulfate in the cochlea after application of a thiosulfate-containing high viscosity formulation of sodium hyaluronan (HYA gel) to the middle ear prior to i.v. injection of cisplatin in a guinea pig model.

METHODS

The release of thiosulfate (0.1 M) from HYA gel (0.5% w/w) was explored in vitro. Thiosulfate in the scala tympani perilymph of the cochlea 1 and 3 h after application of thiosulfate in HYA gel to the middle ear was quantified with HPLC and fluorescence detection. Thiosulfate in blood and CSF was also explored. The potential otoprotective effect was evaluated by hair cell count after treatment with thiosulfate in HYA gel applied to the middle ear 3 h prior to cisplatin injection (8 mg/kg b.w.).

RESULTS

HYA did not impede the release of thiosulfate. Middle ear administration of thiosulfate in HYA gel gave high concentrations in the scala tympani perilymph while maintaining low levels in blood, and it protected against cisplatin-induced hair cell loss.

CONCLUSION

HYA gel is an effective vehicle for administration of thiosulfate to the middle ear. Local application of a thiosulfate-containing HYA gel reduces the ototoxicity of cisplatin most likely without compromising its antineoplastic effect. This provides a minimally invasive protective treatment that can easily be repeated if necessary.

Early self-care rehabilitation of head and neck cancer patients

Conclusions: No positive effects of early preventive rehabilitation could be identified. The results do not contradict the proposition that rehabilitation based on self-care can be effective but it is important to establish evidence-based training programs and identify proper instruments for selection of patients and evaluation of intervention. Objectives: Patients with head and neck cancer suffer from functional impairments due to intense treatment. In this study, we investigated the effectiveness of an experimental early preventive rehabilitation using hard, objective end points in a nonselective, longitudinal, prospective cohort study. Methods: In all, 190 patients were included in the program and received instructions for training before the start of treatment with the aim of reducing swallowing problems and reducing mouth opening and stiffness in the neck. A control group of 184 patients was recruited. Results: There was no difference in weight loss and 2-year survival between the two groups. No positive effects concerning functional impairments were found in patient-reported outcome measures.

Morbidity of supraomohyoidal and modified radical neck dissection combined with radiotherapy for head and neck cancer: a prospective longitudinal study

BACKGROUND

The purpose of this study was to show the investigated impact of supraomohyoidal neck dissection and modified radical neck dissection, both combined with radiotherapy, on cervical range of motion (CROM), mouth opening, swallowing, lymphedema, and shoulder function.

METHODS

One hundred eight patients who had neck dissections and 98 patients who had non-neck dissections were evaluated in a prospective, nonselective, longitudinal cohort study by a physiotherapist and a speech-language pathologist (SLP) before the start of radiotherapy and up to 12 months after treatment.

RESULTS

The incidence of shoulder disability after neck dissection was 18%. Supraomohyoidal neck dissection had no significant effect on the evaluated parameters at any time point. Modified radical neck dissection significantly reduced CROM and mouth opening 2 months after treatment, but after 12 months only cervical rotation was still significantly reduced.

CONCLUSION

In patients treated with external beam radiation (EBRT), modified radical neck dissection induced additional morbidity regarding CROM but not regarding mouth opening, swallowing, and lymphedema 1 year after treatment. Both modified radical neck dissection and supraomohyoidal neck dissection induced shoulder disability.

miRNA analysis of formalin-fixed squamous cell carcinomas of the tongue is affected by age of the samples

Global miRNA expression arrays were used for analysis of 836 miRNAs in formalin-fixed paraffin-embedded samples from 21 tongue cancer patients and 8 controls. Samples had been stored for one to eleven years. Results separated tumour samples from controls, however, the largest variation was correlated to sample storage time, detectable already after one year. With the use of a linear regression model we could adjust for the storage-dependent effect, leading to the identification of 54 differentially expressed miRNAs in tongue cancer, compared to 16 when using standard normalization, including up-regulation of a novel miRNA, miR-424.

Esophageal stricture after radiotherapy in patients with head and neck cancer: experience of a single institution over 2 treatment periods

BACKGROUND

Risk factors for development of a stricture of the upper esophagus after radiotherapy for head and neck cancer are poorly defined.

METHODS

This was a retrospective case-control study of patients diagnosed and treated for esophageal stricture after radiotherapy for head and neck cancer.

RESULTS

The incidence of esophageal stricture after external beam radiation therapy (EBRT) was 3.3%. Seventy patients with stricture and 66 patients without stricture were identified. A multivariate analysis showed that there was increased risk of stricture in receiving enteral feeding during EBRT or in receiving a mean dose of >45 Gy to the upper esophagus.

CONCLUSIONS

Enteral feeding during EBRT is strongly associated with the development of stricture of the esophagus, as is a mean dose of >45 Gy to the upper esophagus. Treatment of the stricture with Savary-Gilliard bougienage or through scope balloon dilatation is safe and successful but often has to be repeated.

Dose-response relations for stricture in the proximal oesophagus from head and neck radiotherapy

BACKGROUND AND PURPOSE

Determination of the dose-response relations for oesophageal stricture after radiotherapy of the head and neck.

MATERIAL AND METHODS

In this study 33 patients who developed oesophageal stricture and 39 patients as controls are included. The patients received radiation therapy for head and neck cancer at Karolinska University Hospital, Stockholm, Sweden. For each patient the 3D dose distribution delivered to the upper 5 cm of the oesophagus was analysed. The analysis was conducted for two periods, 1992-2000 and 2001-2005, due to the different irradiation techniques used. The fitting has been done using the relative seriality model.

RESULTS

For the treatment period 1992-2005, the mean doses were 49.8 and 33.4 Gy, respectively, for the cases and the controls. For the period 1992-2000, the mean doses for the cases and the controls were 49.9 and 45.9 Gy and for the period 2001-2005 were 49.8 and 21.4 Gy. For the period 2001-2005 the best estimates of the dose-response parameters are D(50)=61.5 Gy (52.9-84.9 Gy), γ=1.4 (0.8-2.6) and s=0.1 (0.01-0.3).

CONCLUSIONS

Radiation-induced strictures were found to have a dose response relation and volume dependence (low relative seriality) for the treatment period 2001-2005. However, no dose response relation was found for the complete material.

Tubulin α-6 chain is a stably expressed reference gene in archival samples of normal oral tissue and oral squamous cell carcinoma

One of the most critical factors in gene expression studies using quantitative real-time PCR is the choice of reference gene. Many of the commonly used reference genes have been shown to vary during a number of biological processes as well as between tissues. It is therefore important to always verify the stability of the gene of choice for all new tissues and experimental conditions. Here, we used two publicly available computer software packages (GeNorm and NormFinder) to investigate the stability of eight potential reference genes in formalin-fixed paraffin-embedded (FFPE) samples from normal oral tissue of different origin as well as from oral squamous cell carcinomas. Both programs found the tubulin α-6 chain (TUBA6) and ribosomal protein S13 (RPS13) to have the most stable expression between malignant and non-malignant tissue. NormFinder also found TUBA6 to be the most stable gene when samples were grouped according to tissue origin. FFPE samples constitute a large research resource, which considerably increases the number of samples available for analysis, leading to more reliable conclusions. Verification of a proper reference gene in oral FFPE tissue is therefore of great importance for future studies.

Gene expression profiling of archival tongue squamous cell carcinomas provides sub-classification based on DNA repair genes

A subgroup of patients with squamous cell carcinoma of the head and neck (SCCHN) comprise young persons under the age of 40, who have not been heavily exposed to the classical risk factors, smoking and alcohol. The number of SCCHN in young adults, particularly tongue tumours, is increasing in several parts of the world. Here we employed a novel gene expression array methodology specifically developed for analysis of degraded RNA and investigated the expression of 502 cancer-related genes in archival paraffin-embedded SCCHN of the tongue from young (< or =40) and elderly patients (> or =50). Genes detected as de-regulated in tumours compared to non-malignant controls were in concordance with results from earlier studies of fresh frozen material. No genes were detected as significantly differentially expressed between young and old patients suggesting that the overall pathobiology of SCCHN is similar in young and old. Unsupervised clustering divided tumours into three groups, irrespective of age, where several differentially expressed DNA repair genes were a prominent separation factor. High levels of DNA repair genes associated with impaired therapeutic response to radiation, suggesting that DNA repair genes play a role in clinical outcome after radiotherapy.