Tumor hypoxia is independent of hemoglobin and prognostic for loco-regional tumor control after primary radiotherapy in advanced head and neck cancer

The emerging era of personalized therapy in squamous cell carcinoma of the head and neck

Over the past three decades there has been a move toward organ preservation protocols in the management of locally advanced mucosal head and neck squamous cell carcinomas (LAHNSCC) with combinations of radiotherapy (RT), chemotherapy and, more recently, biological agents. Current standard chemoradiation strategies have reached the upper limits of toxicity. In addition, the traditional one size fits all approach of grouping patients according to traditional clinicopathological features fails to take into account the vast underlying biological heterogeneity of tumors and their host. A number of recent advances such as highly conformal RT, molecular profiling and targeted agents, and improvements in treatment response assessment have set the scene for a fundamental paradigm shift toward greater tailoring of therapy with the aim of improving outcomes and reducing the burden of survivorship. This review focuses on the recognition of the prognostic value of tumor human papillomavirus (HPV) status, the incorporation of biologically targeted therapies and the evolving role of molecular imaging in predicting tumor response and prognosis in the curative management of LAHNSCC.

Definitive Radiotherapy versus Postoperative Radiotherapy of Patients with Oro- and Hypopharyngeal Cancer: Impact of Prognostic Factors

Purpose. To compare the impact of prognostic factors of patients treated with definitive radio(chemo)therapy versus patients treated with surgery and postoperative radiotherapy for squamous cell carcinoma of the oro- and hypopharynx. Patients and Methods. 162 patients treated with definitive radiotherapy and 126 patients treated with postoperative radiotherapy were retrospectively analysed. The impact of the prognostic factors gender, age, total tumor volume (TTV), pre-radiotherapy hemoglobin level (Hb-level), tumor site, T- and N-classification, radiotherapy interruptions >5 days, radiotherapy versus simultaneous radiochemotherapy, R-status and time interval between surgery and radiotherapy were investigated. Results. The median follow-up time for the censored patients treated with definitive radio(chemo)therapy was 28.5 months and for postoperative radiotherapy 36.5 months. On univariate analysis, the TTV, Hb-level, and simultaneous radiochemotherapy had a significant impact on the survival of patients treated with definitive radio(chemo)therapy. For patients treated with postoperative radiotherapy, only the TTV showed a statistical trend for the survival (P = 0.13). On multivariate analysis, the TTV and simultaneous radiochemotherapy maintained their statistical significance for patients treated with definitive raditherapy, and the TTV, the statistical trend for patients treated with postoperative radiotherapy (P = 0.19). Conclusions. The TTV was the predominant prognostic factor for both, patients treated with definitive or postoperative radiotherapy.

DLK1, delta-like 1 homolog (Drosophila), regulates tumor cell differentiation in vivo

The stem cell-like characteristics of tumor cells are not only essential for tumor development and malignant progression, but also significantly contribute to therapy resistance. However, it remains poorly understood how cancer cell differentiation or stemness is regulated in vivo. We investigated the role of the stem cell gene DLK1, or delta-like 1 homolog (Drosophila), in the regulation of cancer cell differentiation in vivo using neuroblastoma (NB) xenografts as a model. We found that loss-of-function mutants of DLK1 significantly enhanced NB cell differentiation in vivo likely by increasing the basal phosphorylation of MEK and ERK kinases, a mechanism that has been shown to facilitate neuronal differentiation. We also found that DLK1(+) cells are preferentially located in hypoxic regions. These results clearly demonstrate that DLK1 plays an important role in the maintenance of undifferentiated, stem cell-like phenotypes of NB cells in vivo.

Monte Carlo radiotherapy simulations of accelerated repopulation and reoxygenation for hypoxic head and neck cancer

OBJECTIVE

A temporal Monte Carlo tumour growth and radiotherapy effect model (HYP-RT) simulating hypoxia in head and neck cancer has been developed and used to analyse parameters influencing cell kill during conventionally fractionated radiotherapy. The model was designed to simulate individual cell division up to 10(8) cells, while incorporating radiobiological effects, including accelerated repopulation and reoxygenation during treatment.

METHOD

Reoxygenation of hypoxic tumours has been modelled using randomised increments of oxygen to tumour cells after each treatment fraction. The process of accelerated repopulation has been modelled by increasing the symmetrical stem cell division probability. Both phenomena were onset immediately or after a number of weeks of simulated treatment.

RESULTS

The extra dose required to control (total cell kill) hypoxic vs oxic tumours was 15-25% (8-20 Gy for 5 × 2 Gy per week) depending on the timing of accelerated repopulation onset. Reoxygenation of hypoxic tumours resulted in resensitisation and reduction in total dose required by approximately 10%, depending on the time of onset. When modelled simultaneously, accelerated repopulation and reoxygenation affected cell kill in hypoxic tumours in a similar manner to when the phenomena were modelled individually; however, the degree was altered, with non-additive results. Simulation results were in good agreement with standard linear quadratic theory; however, differed for more complex comparisons where hypoxia, reoxygenation as well as accelerated repopulation effects were considered.

CONCLUSION

Simulations have quantitatively confirmed the need for patient individualisation in radiotherapy for hypoxic head and neck tumours, and have shown the benefits of modelling complex and dynamic processes using Monte Carlo methods.

Does transfusion improve the outcome for HNSCC patients treated with radiotherapy? - results from the randomized DAHANCA 5 and 7 trials

BACKGROUND

Patients with head and neck squamous cell carcinoma (HNSCC) and a low level of hemoglobin often have a poor response to radiation that may be related to hypoxia-induced radioresistance. We have previously published the importance of hemoglobin level and the effect of transfusion by the results from the randomized DAHANCA 5 trial, including 414 patients in the analysis. Aim of the current analysis was to gain additional power by adding patients from the continued subrandomization in the DAHANCA 7 trial, now including a total of almost 1200 patients.

MATERIAL AND METHODS

Patients were randomized to treatment in the DAHANCA 5 and 7 study (nimorazole vs. placebo and five fx/week vs. six fx/week), and in addition, patients with "low" pre-irradiation hemoglobin values (females <13 g/dl; males <14.5 g/dl) were subrandomized to plus or minus transfusion. Transfusion was given with packed red blood cells with the aim to achieve a hemoglobin level in the "high" value range.

RESULTS

A total of 1166 patients were included, 701 patients had high hemoglobin levels and 465 had low hemoglobin levels. Among the low hemoglobin patients, 235 were randomized to receive transfusion. Patient characteristics and treatment arms were well balanced. In the majority of patients, transfusion resulted in increased hemoglobin levels although this decreased slightly throughout treatment as in the non-transfused patients. Overall, the patients with low hemoglobin level had a significant reduced probability of locoregional control, disease-specific and overall survival. In the low hemoglobin group, transfusion did not improve the outcome in locoregional control, disease-specific or overall survival. In multivariate analyses, HPV/p16 status, T and N classification were significant factors for all outcome measures, whereas there was no significant influence of transfusion or hemoglobin level on endpoints.

CONCLUSION

Transfusion prior to and during radiation treatment did not improve the outcome in patients with HNSCC and low hemoglobin values, but may have a negative impact on survival.

The importance of haemoglobin level and effect of transfusion in HNSCC patients treated with radiotherapy--results from the randomized DAHANCA 5 study

BACKGROUND AND PURPOSE

Patients with head and neck squamous cell carcinoma (HNSCC) and a low level of haemoglobin (Hb) often have a poor response to radiation which may be related to hypoxia induced radioresistance. The aim of the study was to evaluate the prognostic significance of low Hb level and its modification by transfusion in HNSCC patients treated with radiotherapy. The study was performed as a subrandomization in the DAHANCA 5 trial.

MATERIAL AND METHODS

Patients were randomized to treatment with the hypoxic radiosensitizer nimorazole or placebo, and in addition, patients with "low" pre-irradiation Hb values (females<13 g/dL; males<14.5 g/dL) were subrandomized to plus or minus transfusion. Transfusion was given with packed red blood cells with the aim to achieve a Hb level in the "high" value range.

RESULTS

A total of 414 patients were included, 243 patients had high Hb levels and 171 patients had low Hb levels. Of the low Hb patients, 82 were randomized to receive transfusion and 89 not to receive transfusion. The treatment arms were well balanced. In the majority of patients, transfusion resulted in increased Hb levels although this tended to decline throughout treatment. Patients with high Hb levels had a significantly better probability of locoregional control, disease-specific survival and overall survival compared to 'low Hb no transfusion' patients. In the low Hb group, transfusion did not improve the outcome in locoregional control, disease-specific survival or overall survival. In multivariate analyses, T and N classifications were significant for all outcome measures, whereas there was no significant influence of transfusion or Hb level on endpoints.

CONCLUSION

The univariate prognostic significance of high Hb level was demonstrated in patients with HNSCC treated with radiotherapy; however, transfusion prior to and during treatment did not improve the outcome in patients with low Hb values.

Evaluating repetitive 18F-fluoroazomycin-arabinoside (18FAZA) PET in the setting of MRI guided adaptive radiotherapy in cervical cancer

BACKGROUND

The aim of this pilot study was to assess tumour hypoxia in patients with cervical cancer before, during and after combined radio-chemotherapy and Magnetic Resonance Imaging (MRI) guided brachytherapy (BT) by use of the hypoxia Positron Emission Tomography (PET) tracer (18)F-fluoroazomycin-arabinoside ((18)FAZA ).

MATERIAL AND METHODS

Fifteen consecutive patients with locally advanced cervical cancer referred for definitive radiotherapy (RT) were included in an approved clinical protocol. Stage distribution was 3 IB1, 1 IB2, 10 IIB, 1 IIIB, tumour volume was 55 cm(3) (+/- 67, SD). Dynamic and static (18)FAZA -PET scans were performed before, during and after external beam therapy (EBRT) and image guided BT +/- concomitant cisplatin. Dose was prescribed to the individual High Risk Clinical Target Volume (HR CTV) taking into account the dose volume constraints for adjacent organs at risk.

RESULTS

Five patients had visually identifiable tumours on (18)FAZA -PET scans performed prior to radio-chemotherapy and four patients before brachytherapy. One of five (18)FAZA PET positive patients had incomplete remission three months after RT, one had regional recurrence. Four of ten (18)FAZA-PET negative patients developed distant metastases. The one patient with incomplete remission received 69 Gy (D90) in the HR CTV, whereas all other patients received mean 99 Gy (+/-12, SD).

CONCLUSION

PET imaging with (18)FAZA is feasible in patients with cancer of the uterine cervix. However, its predictive and prognostic value remains to be clarified. This applies in particular for the additional value of (18)FAZA-PET compared to morphologic repetitive MRI within the setting of image guided high dose radiotherapy which may contribute to overcome hypoxia related radioresistance.

Measurement of reoxygenation during fractionated radiotherapy in head and neck squamous cell carcinoma xenografts

Hypoxic tissues lack adequate oxygenation and it has been long established that tumours commonly exhibit hypoxia and that hypoxia is a factor contributing towards resistance to radiotherapy. To develop computer models and make predictions about the affects of tumour hypoxia on treatment outcome, quantitative tumour oxygenation and reoxygenation data from in vivo systems is required. The aim of this study was to investigate the timing and degree of reoxygenation during radiotherapy in a human head and neck squamous cell carcinoma xenograft mouse model (FaDu). Mice were immobilised using a novel restraining system and exposed unanaesthetised in 3 or 5 Gy fractions, up to a maximum of 40 Gy. Partial pressures of oxygen (pO2) measurements were recorded at six time points throughout the 2 week course of radiotherapy, using a fibre optic system. Tumours receiving 0-30 Gy did not exhibit an increase in pO2. However, the mean pO2 after 2 weeks of accelerated fractionated radiotherapy (40 Gy) was significantly increased (P<0.01) compared to the mean pO2 of tumours not receiving the full schedule (0-30 Gy). These results lead to the conclusion of an average reoxygenation onset time of 2 weeks in this group of xenografts. A relatively large range of pO2 values measured at each dose point in the study indicate a large inter-tumour variation in oxygenation among the tumours. Data from this experimental work will be used to define the range of reoxygenation onset times implemented in a Monte Carlo computer model, simulating hypoxic head and neck cancer growth and radiotherapy.

The prognostic value of hemoglobin in patients with anal cancer treated with chemoradiotherapy

PURPOSE

This study aimed to evaluate the impact of hemoglobin level on clinical outcome (local response, progression-free survival, and overall survival) in patients with carcinoma of the anal canal treated with definitive chemoradiotherapy.

METHODS

This is a retrospective study of patients with anal cancer treated between 1992 and 2005 with definitive chemoradiotherapy at Tom Baker Cancer Centre. Patient treatment, laboratory, and outcome data were extracted from the chart.

RESULTS

Seventy-two patients treated with definitive chemoradiotherapy were identified. The median age was 56 years, the male-to-female ratio was 1:2, and the median tumor size was 3.5 cm. At 6 weeks after the completion of chemoradiotherapy, 62% of patients (38/61) had complete clinical response, and 34% (21/61) had achieved a partial clinical response. At 3 months after treatment, complete clinical response was observed in 78% (49/63) and a partial response in 16% (10/63). The median pretreatment hemoglobin level was 138.5 g/L, and the median on-treatment hemoglobin level was 129 g/L. Distant relapse was associated with hemoglobin levels in the lowest quartiles, pretreatment and on-treatment (P = .007 and P = .008, respectively). Hemoglobin levels were not associated with response at 6 weeks or 3 months. A pretreatment hemoglobin level of <130 g/L was associated with worse progression-free and overall survival (P < .0001, both). A hemoglobin on-treatment level of <121 g/L was associated with progression-free and overall survival (P < .0001 and P = .019, respectively), when stratified by gender.

CONCLUSIONS

Hemoglobin status was correlated with progression-free and overall survival, and distant relapse, but not clinical response, in patients with carcinoma of the anal canal treated with chemoradiotherapy. The clinically relevant cut point, and the value of correcting hemoglobin levels before or during treatment, remains to be elucidated.

Impact of the hypoxic tumor microenvironment on the regulation of cancer stem cell characteristics

Solid tumors often contain regions with insufficient oxygen delivery, a condition called hypoxia. Tumor hypoxia is an independent prognostic factor significantly correlated with advanced stages of malignancy, increased resistance to conventional therapy, and reduced disease-free survival. Hypoxic tumor cells exhibit poorly differentiated phenotypes resembling stem or progenitor cells. Studies have shown that hypoxia can inhibit tumor cell differentiation and promote maintenance of cancer stem cells. In addition, hypoxia also blocks the differentiation of mesenchymal stem/progenitor cells, a potential source of tumor-associated stromal cells. Therefore, hypoxia may play a critical role during the evolution of the tumor stromal microenvironment and formation of the putative cancer stem cell niches. Conceptually, hypoxia may help create a microenvironment enriched both in poorly differentiated tumor cells and in undifferentiated stromal cells. Such an undifferentiated hypoxic microenvironment may provide essential cellular interactions and environmental signals for the preferential maintenance of cancer stem cells. This review will discuss the hypoxia-regulated stem cell pathways and their roles in the maintenance of cancer stem cell functions.

The role of Human papillomavirus in head and neck cancer and the impact on radiotherapy outcome

The profound influence of Human papillomavirus (HPV) on the epidemiological pattern and clinical course of head and neck cancer (HNSCC) has led to a change in the traditional understanding of this disease entity. Separate therapeutic strategies based on tumour HPV status are under consideration and in this light provision of knowledge concerning the influence of tumour HPV on the radiation response in HNSCC appears highly relevant. This review provides a summary of the current understanding of the role of HPV in head and neck cancer with specific focus on the viral impact on radiotherapy outcome of HNSCC.

HPV-associated p16-expression and response to hypoxic modification of radiotherapy in head and neck cancer

BACKGROUND

HPV/p16-positive head and neck cancers (HNSCC) show superior response to radiotherapy, compared with virus-negative tumours. Tumour hypoxia induces radioresistance and the randomised DAHANCA 5 trial found that the hypoxic cell radiosensitiser nimorazole significantly improved the outcome in HNSCC. Using p16-status as a retrospective stratification parameter, we aimed to assess the influence of p16-expression on the response to nimorazole in HNSCC.

MATERIALS AND METHODS

Pre-treatment tumour blocks were available from 331 of the 414 patients in the DAHANCA 5 trial and evaluated by immunohistochemistry for p16-expression. The influence of p16-expression on outcome was analysed as a function of treatment group (nimorazole/placebo) 5 years after radiotherapy.

RESULTS

Overall, patients treated with nimorazole had significantly better loco-regional control than did those given placebo: hazard ratio (HR) 0.70 [95% CI 0.52-0.93]. Positive expression of p16 also significantly improved outcome after radiotherapy (0.41 [0.28-0.61]). In the subgroup of patients with p16-negative tumours, loco-regional failure was more frequent in the placebo group than in the nimorazole group (0.69 [0.50-0.95]). However, in the p16-positive group, patients treated with nimorazole had a loco-regional control rate similar to patients given placebo (0.93 [0.45-1.91]).

CONCLUSIONS

HPV/p16-expression significantly improved outcome after radiotherapy in HNSCC. Hypoxic modification improved outcome in HPV/p16-negative tumours but was of no significant benefit in HPV/p16-positive tumours, suggesting that hypoxic radioresistance may not be clinically relevant in these tumours.

Resolution in PET hypoxia imaging: voxel size matters

INTRODUCTION

Tumor hypoxia adversely affects treatment outcome, especially in squamous cell carcinomas (SCCs). Image guided radiotherapy (IGRT) based on PET-generated tumor hypoxia maps allows dose boosting to hypoxic sub-volumes and has received considerable interest. However, the combination of slow oxygenation-dependent tracer retention, slow clearance of unbound tracer from non-hypoxic tissue and the necessity to average signal over large non-homogenous tissue areas due to the low PET resolution remains problematic.

MATERIALS AND METHODS

To assess pitfalls inherent to low-resolution imaging we have analyzed the fine-scale distribution of a PET hypoxia tracer (autoradiograms) and tissue architecture (immunofluorescence microscopy) in sectioned experimental SCCs, and compared the results to those obtained when applying macroscopic averaging mimicking the resolution in clinical PET scanners.

RESULTS AND DISCUSSION

We show that tumor areas that would be classified as non-hypoxic based on simple PET threshold identification, often contains foci of hypoxic cells, in particular in tumors where necrosis and severely hypoxic cells are intermixed. In contrast, in a non-necrotic tumor model we found that the risk of missing hypoxic cells was greatly reduced, however, its patchy hypoxic pattern made a clear delineation of a target to boost unfeasible. We discuss the implications of these and other complicating factors in PET hypoxia-imaging and outline future strategies to overcome or circumvent them.

Weekly low-dose docetaxel-based chemoradiotherapy for locally advanced oropharyngeal or hypopharyngeal carcinoma: a retrospective, single-institution study

PURPOSE

To retrospectively assess the efficacy, toxicity, and prognostic factors of weekly low-dose docetaxel-based chemoradiotherapy for Stage III/IV oropharyngeal or hypopharyngeal carcinoma.

METHODS AND MATERIALS

Between 2001 and 2005, 72 consecutive patients with locally advanced oropharyngeal or hypopharyngeal carcinoma were treated with concurrent chemoradiotherapy (CCR; radiation at 60 Gy plus weekly docetaxel [10 mg/m(2)]). Thirty of these patients also received neoadjuvant chemotherapy (NAC; docetaxel, cisplatin, and 5-fluorouracil) before concurrent chemoradiotherapy. Survival was calculated according to the Kaplan-Meier method. The prognostic factors were evaluated by univariate and multivariate analyses.

RESULTS

The median follow-up was 33 months, with overall survival, disease-free survival, and locoregional control rates at 3 years of 59%, 45%, and 52%, respectively. Thirty-six patients (50%) experienced more than one Grade 3 to 4 acute toxicity. Grade 3 mucositis occurred in 32 patients (44%), Grade 4 laryngeal edema in 1 (1%). Grade > or =3 severe hematologic toxicity was observed in only 2 patients (3%). Grade 3 dysphagia occurred as a late complication in 2 patients (3%). Multivariate analyses identified age, T stage, hemoglobin level, and completion of weekly docetaxel, but not NAC, as significant factors determining disease-free survival.

CONCLUSIONS

Docetaxel is an active agent used in both concurrent and sequential chemoradiotherapy regimens. Mucositis was the major acute toxicity, but this was well tolerated in most subjects. Anemia was the most significant prognostic factor determining survival. Further studies are warranted to investigate the optimal protocol for integrating docetaxel into first-line chemoradiotherapy regimens, as well as the potential additive impact of NAC.

Immunohistochemical detection of changes in tumor hypoxia

PURPOSE

Although hypoxia is a known prognostic factor, its effect will be modified by the rate of reoxygenation and the extent to which the cells are acutely hypoxic. We tested the ability of exogenous and endogenous markers to detect reoxygenation in a xenograft model. Our technique might be applicable to stored patient samples.

METHODS AND MATERIALS

The human colorectal carcinoma line, HT29, was grown in nude mice. Changes in tumor hypoxia were examined by injection of pimonidazole, followed 24 hours later by EF5. Cryosections were stained for these markers and for carbonic anhydrase IX (CAIX) and hypoxia-inducible factor 1alpha (HIF1alpha). Tumor hypoxia was artificially manipulated by carbogen exposure.

RESULTS

In unstressed tumors, all four markers showed very similar spatial distributions. After carbogen treatment, pimonidazole and EF5 could detect decreased hypoxia. HIF1alpha staining was also decreased relative to CAIX, although the effect was less pronounced than for EF5. Control tumors displayed small regions that had undergone spontaneous changes in tumor hypoxia, as judged by pimonidazole relative to EF5; most of these changes were reflected by CAIX and HIF1alpha.

CONCLUSION

HIF1alpha can be compared with either CAIX or a previously administered nitroimidazole to provide an estimate of reoxygenation.

Prognostic potential of the pre-therapeutic tumor oxygenation status

Hypoxia, a characteristic feature of locally advanced solid tumors, has emerged as a key factor of the tumor pathophysiome, since it can promote tumor progression and resistance to therapy. Independent of established prognostic parameters, such as clinical tumor stage, histology, histological grade and nodal status, hypoxia has been identified as an adverse prognostic factor for patient outcome. Studies of pretreatment tumor hypoxia involving direct assessment (polarographic oxygen tension measurements) have suggested a poor prognosis for patients with hypoxic tumors. These investigations indicate a worse disease-free survival for patients with hypoxic cancers of the uterine cervix or soft tissue sarcomas. In head & neck cancers, the studies suggest that pretherapeutic hypoxia is prognostic for survival and local control.

Prognostic significance of tumor hypoxia inducible factor-1alpha expression for outcome after radiotherapy in oropharyngeal cancer

PURPOSE

Head-and-neck squamous cell carcinoma (HNSCC) represents a heterogeneous group of patients in terms of subsite, treatment, and biology. Currently most management decisions are based on clinical parameters with little appreciation of patient differences in underlying tumor biology. We investigated the prognostic significance of clinicopathologic features and tumor hypoxia-inducible factor-1alpha (HIF-1alpha) expression in a homogeneous series of patients who underwent radiotherapy.

METHODS AND MATERIALS

An audit identified 133 consecutive patients with histologically proven squamous cell carcinoma of the tonsil or tongue base. All patients received primary radiotherapy between 1996 and 2001. Tumor HIF-1alpha expression was examined in 79 patients.

RESULTS

Features associated with poor locoregional control were low Hb level (p = 0.05) and advancing T (p = 0.008), N (p = 0.03), and disease (p = 0.008) stage. HIF-1alpha expression was a more significant adverse prognostic factor in the tonsil (hazard ratio [HR], 23.1; 95% confidence interval [CI]. 3.04-176.7) than the tongue-base tumor (HR, 2.86; 95% CI, 1.14-7.19) group (p = 0.03, test for interaction). High tumor HIF-1alpha expression was associated with low blood Hb levels (p = 0.03). In a multivariate analysis HIF-1alpha expression retained prognostic significance for locoregional control (HR, 7.10; 95% CI, 3.07-16.43) and cancer-specific survival (HR, 9.19; 95% CI, 3.90-21.6).

CONCLUSIONS

There are significant differences in radiation therapy outcome within a homogeneous subsite of the oropharynx related to molecular marker expression. The work highlights the importance of studying homogeneous groups of patients in HNSCC, and the complex interrelationships between tumor biology and clinicopathologic factors. The establishment of tumor-type specific markers would represent a major advance in this area.

Solid tumor physiology and hypoxia-induced chemo/radio-resistance: novel strategy for cancer therapy: nitric oxide donor as a therapeutic enhancer

Hypoxia exists in solid tumor tissues due to abnormal vasculature, vascular insufficiency, treatment or malignancy related anemia, and low intratumor blood flow. Hypoxic status in solid tumor promotes accumulation of hypoxia-inducible factor-1 alpha which is promptly degraded by proteasomal ubiquitination under normoxic conditions. However, under hypoxic conditions, the ubiquitination system for HIF-1 alpha is inhibited by inactivation of prolyl hydroxylase which is responsible for hydroxylation of proline in the oxygen-dependent degradation domain of HIF-1 alpha. HIF-1 alpha is an important transcriptional factor that codes for hundreds of genes involved in erythropoiesis, angiogenesis, induction of glycolytic enzymes in tumor tissues, modulation of cancer cell cycle, cancer proliferation, and cancer metastasis. Hypoxia and accumulation of HIF-1 alpha in solid tumor tissues have been reported to associate with resistance to chemotherapy, radiotherapy, and immunotherapy and poor prognosis. Production of vascular endothelial growth factor (VEGF) in cancer cells is regulated by the activated HIF-1 mediated system. An increase in VEGF levels subsequently induces HIF-1 alpha accumulation and promotes tumor metastasis by angiogenesis. Recently, angiogenesis targeting therapy using humanized VEGF antibody and VEGF receptor tyrosine kinase inhibitors have been used in solid cancer therapy. Nitric oxide (NO) is a unique chemical gaseous molecule that plays a role as a chemical messenger involved in vasodilator, neurotransmitter, and anti-platelet aggregation. In vivo, NO is produced and released from three different isoforms of NO synthase (NOS) and from exogenously administered NO donors. In cancer science, NO has been mainly discussed as an oncogenic molecule over the past decades. However, NO has recently been noted in cancer biology associated with cancer cell apoptosis, cancer cell cycle, cancer progression and metastasis, cancer angiogenesis, cancer chemoprevention, and modulator for chemo/radio/immuno-therapy. The presence and activities of all the three isoforms of NOS and were detected in cancer tissue components such as cancer cells, tumor-associated macrophages, and vascular endothelium. Overexpression of iNOS in cancer tissues has been reported to associate with poor prognosis in patients with cancers. On the other hand, NO donors such as nitroglycerin have been demonstrated to improve the effects of cancer therapy in solid cancers. Nitroglycerin has been used safely for a long time as a potent vasodilator for the treatment of ischemic heart diseases or heart failure. Therefore, we think highly of clinical use of nitroglycerin as a novel cancer therapy in combination with anticancer drugs for improvement of cancer therapeutic levels. In this review article, we demonstrate the unique physiological characteristics of malignant solid tumors, several factors in solid tumors resulting in resistance for cancer therapies, and the effects of NO from NOS or exogenous NO-donating drugs on malignant cells. Furthermore, we refer to promising therapeutic roles of NO and NO-donating drugs for novel treatments in solid tumors.

Tissue oxygenation in a murine SCC VII tumor after X-ray irradiation as determined by EPR spectroscopy

PURPOSE

The goal of this study was to clarify the dynamics of oxygenation (partial pressure of oxygen, pO(2)) in SCC VII murine tumors in mice after X-ray irradiation.

MATERIALS AND METHODS

Changes in pO(2) in tumors were measured by 1.2-GHz electron paramagnetic resonance (EPR) spectroscopy after they were exposed to various doses of irradiation. The pO(2) in tumors was followed for up to six days after irradiation at doses of 0, 5, 10, 15, and 20 Gy. Paramagnetic crystals were used as an oximetry probe and implanted into normal or tumor tissues in mice for prolonged periods.

RESULTS

The pattern of tumor oxygen after a single dose of radiation with the 5-Gy dose was different from those with other doses (10, 15, and 20 Gy). After 5 Gy, pO(2) increased rapidly (P<0.01, Student's t test) and then returned to the level observed before irradiation by 12h (P<0.01). In contrast, after 10, 15, or 20 Gy, pO(2) increased rapidly by 6h after irradiation, continued to increase until at least 24h (P<0.01), and then gradually decreased.

CONCLUSIONS

In tumors that received 5 Gy, post-irradiation increases in pO(2) at 4h after irradiation were detected by EPR oximetry (P<0.01) noninvasively.

Phase III trial to evaluate the efficacy of maintaining hemoglobin levels above 12.0 g/dL with erythropoietin vs above 10.0 g/dL without erythropoietin in anemic patients receiving concurrent radiation and cisplatin for cervical cancer

PURPOSE

To determine whether maintaining HGB levels > or = 12.0 g/dL with recombinant human erythropoietin (R-HUEPO) compared to "standard" treatment (transfusion for HGB < or = 10.0 g/dL) improves progression-free survival (PFS), overall survival (OS) and local control (LC) in women receiving concurrent weekly cisplatin and radiation (CT/RT) for carcinoma of the cervix. In addition, to determine whether platinum-DNA adducts were associated with clinical characteristics or outcome.

METHODS

Patients with stage IIB-IVA cervical cancer and HGB < 14.0 g/dL were randomly assigned to CT/RT+/-R-HUEPO (40,000 units s.c. weekly). R-HUEPO was stopped if HGB > 14.0 g/dL. Endpoints were PFS, OS and LC. Platinum-DNA adducts were quantified using immunocytochemistry assay in buccal cells.

RESULTS

Between 08/01 and 09/03, 109 of 114 patients accrued were eligible. Fifty-two received CT/RT and 57 CT/RT+R-HUEPO. The study closed prematurely, with less than 25% of the planned accrual, due to potential concerns for thromboembolic event (TE) with R-HUEPO. Median follow-up was 37 months (range 9.8-50.4 months). PFS and OS at 3 years should be 65% and 75% for CT/RT and 58% and 61% for CT/RT+R-HUEPO, respectively. TE occurred in 4/52 receiving CT/RT and 11/57 with CT/RT+R-HUEPO, not all considered treatment related. No deaths occurred from TE. High-platinum adducts were associated with inferior PFS and LC.

CONCLUSION

TE is common in cervical cancer patients receiving CT/RT. Difference in TE rate between the two treatments was not statistically significant. The impact of maintaining HGB level > 12.0 g/dL on PFS, OS and LC remains undetermined.

Tissue characterization of locoregionally advanced head-and-neck squamous cell carcinoma (HNSCC) using quantified ultrasonography: A prospective phase II study on prognostic relevance

BACKGROUND AND PURPOSE

Information on a patient's prognosis is important for the clinical decision-making process. This study explored the capacity of quantitative ultrasound imaging to increase prognostic information.

MATERIALS AND METHODS

High-resolution B-scan and colour-coded duplex-sonography of the neck was prospectively applied to 50 HNSCC-patients stage IVA-B 05/99-01/02 before definite radio-(chemo-)therapy. Every lymph node >1.5 cm was scored for the following Malignancy Criteria: Inhomogeneity, Surface-irregularity, Missing hilar sign, Spherical form, Matting, Aberrant intranodal vessels, Infiltration of surrounding tissue, Intranodal cystic necrosis.

RESULTS

Median Overall Survival (OS) was 1 year. High MMCC (Maximal Malignancy Criteria Count in a single node) predicted a poor outcome with a median OS of 8.1 months (MMCC=7-8, n=24) vs. 24.7 months for low MMCC (1-6, n=26, p=0.0004, logrank). Estimated 1- and 3-year-OS was 25% and 8% for high vs. 69% and 41% for low MMCC. Ten out of eleven living patients (follow-up 2.3-5.3 years) had a low MMCC. Of the clinical parameters determined, only pre-treatment hemoglobin levels <12 g/dl and treatment less radical than chemoradiation to 70 Gy predicted poor OS (univariate p=0.04 and 0.02, respectively). In multivariate Cox analysis, MMCC continued to significantly predict for OS (p=0.002) and Disease-Free Survival (p=0.002).

CONCLUSIONS

Quantification of nodal ultrasonography offers valuable prognostic information for the conservative management of HNSCC.

Fluorine-18-labeled fluoromisonidazole positron emission and computed tomography-guided intensity-modulated radiotherapy for head and neck cancer: a feasibility study

PURPOSE

Hypoxia renders tumor cells radioresistant, limiting locoregional control from radiotherapy (RT). Intensity-modulated RT (IMRT) allows for targeting of the gross tumor volume (GTV) and can potentially deliver a greater dose to hypoxic subvolumes (GTV(h)) while sparing normal tissues. A Monte Carlo model has shown that boosting the GTV(h) increases the tumor control probability. This study examined the feasibility of fluorine-18-labeled fluoromisonidazole positron emission tomography/computed tomography ((18)F-FMISO PET/CT)-guided IMRT with the goal of maximally escalating the dose to radioresistant hypoxic zones in a cohort of head and neck cancer (HNC) patients.

METHODS AND MATERIALS

(18)F-FMISO was administered intravenously for PET imaging. The CT simulation, fluorodeoxyglucose PET/CT, and (18)F-FMISO PET/CT scans were co-registered using the same immobilization methods. The tumor boundaries were defined by clinical examination and available imaging studies, including fluorodeoxyglucose PET/CT. Regions of elevated (18)F-FMISO uptake within the fluorodeoxyglucose PET/CT GTV were targeted for an IMRT boost. Additional targets and/or normal structures were contoured or transferred to treatment planning to generate (18)F-FMISO PET/CT-guided IMRT plans.

RESULTS

The heterogeneous distribution of (18)F-FMISO within the GTV demonstrated variable levels of hypoxia within the tumor. Plans directed at performing (18)F-FMISO PET/CT-guided IMRT for 10 HNC patients achieved 84 Gy to the GTV(h) and 70 Gy to the GTV, without exceeding the normal tissue tolerance. We also attempted to deliver 105 Gy to the GTV(h) for 2 patients and were successful in 1, with normal tissue sparing.

CONCLUSION

It was feasible to dose escalate the GTV(h) to 84 Gy in all 10 patients and in 1 patient to 105 Gy without exceeding the normal tissue tolerance. This information has provided important data for subsequent hypoxia-guided IMRT trials with the goal of further improving locoregional control in HNC patients.

Detection and characterization of tumor hypoxia using pO2 histography

Data from 125 studies describing the pretreatment oxygenation status as measured in the clinical setting using the computerized Eppendorf pO2 histography system have been compiled in this article. Tumor oxygenation is heterogeneous and severely compromised as compared to normal tissue. Hypoxia results from inadequate perfusion and diffusion within tumors and from a reduced O2 transport capacity in anemic patients. The development of tumor hypoxia is independent of a series of relevant tumor characteristics (e.g., clinical size, stage, histology, and grade) and various patient demographics. Overall median pO2 in cancers of the uterine cervix, head and neck, and breast is 10 mm Hg with the overall hypoxic fraction (pO2 <or= 2.5 mm Hg) being approx. 25%. Metastatic lesions do not substantially deviate from the oxygenation status of (their) primary tumors. Whereas normal tissue oxygenation is independent of the hemoglobin level over the range of 8-15 g/dL, hypoxia is more pronounced in anemic patients and above this range in some cancers. Identification of tumor hypoxia may allow an assessment of a tumor's potential to develop an aggressive phenotype or acquired treatment resistance, both of which lead to poor prognosis. Detection of hypoxia in the clinical setting may therefore be helpful in selecting high-risk patients for individual and/or more intensive treatment schedules.

Differential risk assessments from five hypoxia specific assays: The basis for biologically adapted individualized radiotherapy in advanced head and neck cancer patients

PURPOSE

Hypoxia adversely relates with prognosis in human tumours. Five hypoxia specific predictive marker assays were compared and correlated with definitive radiotherapy.

PATIENTS AND METHODS

Sixty-seven patients with advanced head and neck carcinomas were studied for pre-treatment plasma osteopontin measured by ELISA, tumour oxygenation status using pO(2) needle electrodes and tumour osteopontin, hypoxia inducible factor 1alpha (HIF-1alpha) and carboxyanhydrase 9 (CA9) by immunohistochemistry. The primary treatment was radiotherapy and the hypoxic radiosensitizer nimorazole. Loco-regional tumour control was evaluated at 5 years.

RESULTS

All five markers showed inter-tumour variability. Inter-marker correlations were inconsistent. Only plasma osteopontin inversely correlated with median tumour pO(2), (p=0.02, r=0.28) and CA9 correlated with HIF-1alpha (p<0.01, r=0.45). In Kaplan-Meier analysis high plasma osteopontin, high HIF-1alpha and high proportion of tumour pO(2)2.5mmHg (HP(2.5)) related significantly with poorer loco-regional control, whereas CA9 and tumour osteopontin failed to predict loco-regional control in this set dataset. When analyzing Hb, stage, and the five markers by competing risks HP(2.5) was the strongest variable to predict for loco-regional tumour control.

CONCLUSION

There was diversity and lack of correlation among five different hypoxia assays within individual tumours. High plasma osteopontin, high HIF-1alpha and high proportion of tumour pO(2)2.5mmHg (HP(2.5)) related significantly with poorer loco-regional control, whereas CA9 and tumour OPN failed to predict local control.

Metabolic targeting of hypoxia and HIF1 in solid tumors can enhance cytotoxic chemotherapy

Solid tumors frequently contain large regions with low oxygen concentrations (hypoxia). The hypoxic microenvironment induces adaptive changes to tumor cell metabolism, and this alteration can further distort the local microenvironment. The net result of these tumor-specific changes is a microenvironment that inhibits many standard cytotoxic anticancer therapies and predicts for a poor clinical outcome. Pharmacologic targeting of the unique metabolism of solid tumors could alter the tumor microenvironment to provide more favorable conditions for anti-tumor therapy. Here, we describe a strategy in which the mitochondrial metabolism of tumor cells is increased by pharmacologic inhibition of hypoxia-inducible factor 1 (HIF1) or its target gene pyruvate dehydrogenase kinase 1 (PDK1). This acute increase in oxygen consumption leads to a corresponding decrease in tumor oxygenation. Whereas decreased oxygenation could reduce the effectiveness of some traditional therapies, we show that it dramatically increases the effectiveness of a hypoxia-specific cytotoxin. This treatment strategy should provide a high degree of tumor specificity for increasing the effectiveness of hypoxic cytotoxins, as it depends on the activation of HIF1 and the presence of hypoxia, conditions that are present only in the tumor, and not the normal tissue.

Hypoxia in cancer: significance and impact on clinical outcome

Hypoxia, a characteristic feature of locally advanced solid tumors, has emerged as a pivotal factor of the tumor (patho-)physiome since it can promote tumor progression and resistance to therapy. Hypoxia represents a "Janus face" in tumor biology because (a) it is associated with restrained proliferation, differentiation, necrosis or apoptosis, and (b) it can also lead to the development of an aggressive phenotype. Independent of standard prognostic factors, such as tumor stage and nodal status, hypoxia has been suggested as an adverse prognostic factor for patient outcome. Studies of tumor hypoxia involving the direct assessment of the oxygenation status have suggested worse disease-free survival for patients with hypoxic cervical cancers or soft tissue sarcomas. In head & neck cancers the studies suggest that hypoxia is prognostic for survival and local control. Technical limitations of the direct O(2) sensing technique have prompted the use of surrogate markers for tumor hypoxia, such as hypoxia-related endogenous proteins (e.g., HIF-1alpha, GLUT-1, CA IX) or exogenous bioreductive drugs. In many - albeit not in all - studies endogenous markers showed prognostic significance for patient outcome. The prognostic relevance of exogenous markers, however, appears to be limited. Noninvasive assessment of hypoxia using imaging techniques can be achieved with PET or SPECT detection of radiolabeled tracers or with MRI techniques (e.g., BOLD). Clinical experience with these methods regarding patient prognosis is so far only limited. In the clinical studies performed up until now, the lack of standardized treatment protocols, inconsistencies of the endpoints characterizing the oxygenation status and methodological differences (e.g., different immunohistochemical staining procedures) may compromise the power of the prognostic parameter used.

The hypoxic tumour microenvironment, patient selection and hypoxia-modifying treatments

Tumour hypoxia has been found to be a characteristic feature in many solid tumours. It has been shown to decrease the therapeutic efficacy of radiation treatment, surgery and some forms of chemotherapy. Successful approaches have been developed to counteract this resistance mechanism, although usually at the cost of increased short- and long-term side-effects. New methods for qualitative and quantitative assessment of tumour oxygenation have made it possible to establish the prognostic significance of tumour hypoxia. The ability to determine the degree and extent of hypoxia in solid tumours is not only important prognostically, but also in the selection of patients for hypoxia-modifying treatments. To provide the best attainable quality of life for individual patients it is of increasing importance that tools be developed that allow a better selection of patients for these intensified treatment strategies. Several genes and proteins involved in the response to hypoxia have been identified as potential candidates for future use in predictive assays. Although some markers and combinations have shown potential benefit and are associated with treatment outcome, their clinical usefulness needs to be validated in prospective trials. A review of published studies was carried out, focusing on the assessment of tumour hypoxia, patient selection and the possibilities to overcome hypoxia during treatment.

CD24 expression is an independent prognostic marker in cholangiocarcinoma

CD24 has been described as an adverse prognostic marker in several malignancies. This study evaluates CD24 expression in cholangiocarcinoma and correlates the findings with clinicopathologic data and patient survival. Between 1996 and 2002, 22 consecutive patients with cholangiocarcinoma were treated at our institution. Demographic data, SEER stage, pathologic data, treatment, expression of CD24, mitogen-activated protein kinase (MAPK), phosphorylated MAPK, and survival were analyzed. The majority of the tumors demonstrated CD24 (81.8%) and p-MAPK (87%) expression. A negative association was noted between the expression of CD24 and p-MAPK. Median survival for patients with low expression of CD24 was 36 months and high expression was 8 months. Median survival for patients who received chemotherapy with low CD24 expression was 163 months, and for seven patients with high CD24 expression, it was 17 months (p=0.04). With the addition of radiation therapy, median survival for patients with low expression of CD24 was 52 months and high expression was 17 months (p=0.08). On multivariate analysis, the use of chemotherapy (p=0.0014, hazard ratio 0.069) and the CD24 overexpression (p=0.02, hazard ratio 7.528) were predictive of survival. CD24 is commonly expressed in cholangiocarcinoma, and overexpression is predictive of poor survival and possibly of lack of response to chemotherapy and radiation therapy. These findings may improve selection of patients for the appropriate treatment modality and the development of CD24-targeted therapy.

Anemia correction in malignancy management: threat or opportunity?

OBJECTIVES

The presence of anemia and/or hypoxia in cancer patients have both been correlated with worse outcomes. While some retrospective data suggest an improvement in outcomes in cervical cancer patients whose anemia has been corrected, the critical level to which hemoglobin should be raised and the issue of whether raising hemoglobin translates into a survival advantage remain controversial. This debate has more recently expanded to concerns over how we raise hemoglobin, with 2 recent randomized trials suggesting impaired survival outcomes in the groups who received poietic proteins to correct hemoglobin levels to normal and above values.

METHODS

A comprehensive literature search was performed utilizing combinations of the key search words anemia, hypoxia, radiotherapy, HIF-1alpha, angiogenesis, and erythropoietin.

RESULTS

The preponderance of evidence suggest a correlation between both anemia and worse outcome as well as hypoxia and worse outcome; however the relationship between anemia and hypoxia remains complex. A critical review of molecular changes associated with hypoxia that drive the molecular process, anemia correction and the data on the use of poietic proteins, and a review of future directions of research which focus on the opportunity of therapies correcting hypoxia or hypoxia-relevant targets is also presented.

CONCLUSIONS

Anemia and hypoxia remain biologically plausible targets for improving therapy. The potential benefit of raising hemoglobin will depend on whether anemia can influence treatment resistance and whether anemia plays a reversible role in driving the molecular milieu contributing to malignant clonogen survival and dissemination.

The prognostic value of anaemia at different treatment times in patients with locally advanced head and neck cancer treated with surgery and postoperative radiotherapy

AIMS

We report a retrospective mono-institutional analysis of anaemia (< 12 g/dl) at different treatment times (preoperative, postoperative, before radiotherapy and nadir levels during radiotherapy) in head and neck cancer patients treated with surgery and postoperative radiotherapy. The study objective was to determine whether, and at which time points, anaemia had a significant effect on the end points overall survival and local recurrence-free survival (LRFS).

MATERIALS AND METHODS

The end points for the statistical analysis in 130 patients were LRFS and overall survival. A univariate analysis (Log-rank test) was carried out on the following variables with potential end point-related impact: gender, T, N, G, American Joint Committee on Cancer (AJCC) stage, tumour site, resection status, overall treatment time (OTT), radiotherapy treatment time (RTT) and preoperative, postoperative, pre-radiotherapy and nadir levels of haemoglobin during radiotherapy. Individual variables with a significant effect (P=0.05) were then subjected to multivariate Cox regression analysis.

RESULTS

The median overall survival was 59 months. The univariate analysis showed that AJCC stage (P=0.0268), resection status (P=0.0407), preoperative haemoglobin level (P=0.0087), postoperative haemoglobin level (P=0.0035), RTT (P=0.0042) and OTT (P=0.0343) significantly influenced overall survival. OTT (P=0.0130) and postoperative haemoglobin (P=0.0243) had a significant effect on LRFS. The multivariate Cox regression analysis showed postoperative haemoglobin < 12 g/dl and OTT>100 days to be independent negative prognostic factors for both end points.

CONCLUSIONS

Postoperative acute anaemia < 12 g/dl and an OTT>100 days were independent negative prognostic factors for LRFS and overall survival in patients with head and neck cancer treated with surgery and postoperative radiotherapy.

Interrelation of directly measured oxygenation levels, erythropoietin and erythropoietin receptor expression in spontaneous canine tumours

The expression of the hypoxia-inducible protein erythropoietin in tumour cells correlates with levels of tumour hypoxia. Our aim was to look for an interrelation of directly measured oxygenation levels, the presence of tissue erythropoietin and its receptor. Data of tumour oxygenation status, plasma and tissue erythropoietin and its receptor in a group of spontaneously occurring tumours in 15 dogs were collected. Polarographic tumour oxygen partial pressure measurements were obtained and data were correlated. Significant positive correlations were found between tissue erythropoietin and the percentages of pO2 values < or = 10 mmHg. Multivariate analysis revealed no parameters influencing plasma erythropoietin levels. Our results show that a co-expression of erythropoietin receptor and its ligand in spontaneous canine tumours exists, that the level of hypoxia in tumour cells correlates with the level of tissue erythropoietin and suggest the need to be quantitatively and functionally tested as novel prognostic biological parameters in neoplastic tissues.

Fluctuations in tumor blood perfusion assessed by dynamic contrast-enhanced MRI

Temporal heterogeneity in blood perfusion is a common phenomenon in tumors, but data characterizing the nature of the blood flow fluctuations are sparse. This study investigated the occurrence of blood flow fluctuations in A-07 melanoma xenografts by using gadopentetate dimeglumine (Gd-DTPA)-based dynamic contrast-enhanced MRI (DCE-MRI). Each tumor was subjected to two DCE-MRI acquisitions separated by 1 hour. The data were processed by Kety analysis and resulted in two E.F images (E is the initial extraction fraction of Gd-DTPA and F is the perfusion) and two lambda images (lambda is the partition coefficient of Gd-DTPA) for each tumor. The E . F images were used to determine the changes in blood perfusion arising in the time between the two imaging sequences. The lambda images were used to control the reproducibility of the experimental procedure. The study showed that DCE-MRI with subsequent Kety analysis is a useful method for detection of blood flow fluctuations in A-07 tumors, and strongly suggested that the peripheral regions of A-07 tumors are more exposed to temporal changes in blood perfusion than are the central regions.

Treatment with Imatinib in NSCLC is associated with decrease of phosphorylated PDGFR-beta and VEGF expression, decrease in interstitial fluid pressure and improvement of oxygenation

Elevated intratumoral interstitial fluid pressure (IFP) and tumour hypoxia are independent predictive factors for poor survival and poor treatment response in cancer patients. However, the relationship between IFP and tumour hypoxia has not yet been clearly established. Preclinical studies have shown that lowering IFP improves treatment response to cytotoxic therapy. Interstitial fluid pressure can be reduced by inhibition of phosphorylated platelet-derived growth factor receptor-β (p-PDGFR-β), a tyrosine kinase receptor frequently overexpressed in cancer stroma, and/or by inhibition of VEGF, a growth factor commonly overexpressed in tumours overexpressing p-PDGFR-β. We hypothesised that Imatinib, a specific PDGFR-β inhibitor will, in addition to p-PDGFR-β inhibition, downregulate VEGF, decrease IFP and improve tumour oxygenation. A549 human lung adenocarcinoma xenografts overexpressing PDGFR-β were grown in nude mice. Tumour-bearing animals were randomised to control and treatment groups (Imatinib 50 mg kg⁻¹ via gavage for 4 days). Interstitial fluid pressure was measured in both groups before and after treatment. EF5, a hypoxia marker, was administered 3 h before being killed. Tumours were sectioned and stained for p-PDGFR-β, VEGF and EF5 binding. Stained sections were viewed with a fluorescence microscope and image analysis was performed. Imatinib treatment resulted in significant reduction of p-PDGFR-β, VEGF and IFP. Tumour oxygenation was also significantly improved. This study shows that p-PDGFR-β-overexpressing tumours can be effectively treated with Imatinib to decrease tumour IFP. Importantly, this is the first study demonstrating that Imatinib treatment improves tumour oxygenation and downregulates tumour VEGF expression.

Overcoming physiologic barriers to cancer treatment by molecularly targeting the tumor microenvironment

It is widely recognized that the vasculature of the tumor is inadequate to meet the demands of the growing mass. The malformed vasculature is at least in part responsible for regions of the tumor that are hypoxic, acidotic, and exposed to increased interstitial fluid pressure. These unique aspects of the tumor microenvironment have been shown to act as barriers to conventional chemotherapy or radiation-based therapies. It now seems that while the vasculature initiates these tumor-specific conditions, the cells within the tumor respond to these stresses and add to the unique solid tumor physiology. Gene expression changes have been reported in the tumor for vascular endothelial growth factor, carbonic anhydrase IX, and pyruvate dehydrogenase kinase 1. The activity of these gene products then influences the tumor physiology through alterations in vascular permeability and interstitial fluid pressure, extracellular acidosis, and mitochondrial oxygen consumption and hypoxia, respectively. Novel molecular strategies designed to interfere with the activities of these gene products are being devised as ways to overcome the physiologic barriers in the tumor to standard anticancer therapies.

HIF-1 mediates adaptation to hypoxia by actively downregulating mitochondrial oxygen consumption

The HIF-1 transcription factor drives hypoxic gene expression changes that are thought to be adaptive for cells exposed to a reduced-oxygen environment. For example, HIF-1 induces the expression of glycolytic genes. It is presumed that increased glycolysis is necessary to produce energy when low oxygen will not support oxidative phosphorylation at the mitochondria. However, we find that while HIF-1 stimulates glycolysis, it also actively represses mitochondrial function and oxygen consumption by inducing pyruvate dehydrogenase kinase 1 (PDK1). PDK1 phosphorylates and inhibits pyruvate dehydrogenase from using pyruvate to fuel the mitochondrial TCA cycle. This causes a drop in mitochondrial oxygen consumption and results in a relative increase in intracellular oxygen tension. We show by genetic means that HIF-1-dependent block to oxygen utilization results in increased oxygen availability, decreased cell death when total oxygen is limiting, and reduced cell death in response to the hypoxic cytotoxin tirapazamine.

Prognostic Value of Haemoglobin Levels During Concurrent Radio-chemotherapy in the Treatment of Oesophageal Cancer

AIMS

To evaluate the prognostic value of haemoglobin levels during radio-chemotherapy for overall survival, metastases-free survival (MFS) and locoregional control in patients with locally advanced oesophageal cancer.

MATERIALS AND METHODS

Age, gender, performance status, tumour location, tumour length, histology, histologic grading, T-stage, N-stage, UICC-stage and weekly haemoglobin levels during concurrent radio-chemotherapy were retrospectively investigated and related to outcome in 108 patients, who received radio-chemotherapy for stage II/III oesophageal cancer. Radio-chemotherapy consisted of 59.4-60 Gy irradiation, two to four courses of cisplatin (75 mg/m2 on day 1) and 5-fluorouracil (1000 mg/m2 on days 1-5). Haemoglobin levels during radio-chemotherapy were compared among the following three groups: patients with over 60% of haemoglobin levels less than 12 g/dl; patients with over 60% of haemoglobin levels at 12-14 g/dl; and patients with over 60% of haemoglobin levels greater than 14 g/dl.

RESULTS

On univariate analysis, haemoglobin levels of 12-14 g/dl and greater than 14 g/dl during concurrent radio-chemotherapy provided better outcomes than haemoglobin levels less than 12 g/dl. The 2-year overall survival rates were 34%, 35% and 16%, respectively (P = 0.002). The 2-year MFS survival rates were 23%, 46% and 21%, respectively (P = 0.06). The 2-year locoregional control rates were 44%, 58% and 19%, respectively (P < 0.001). ECOG performance status (1 better than 2-3) was significantly associated with overall survival (P = 0.013), tumour length (<7 cm better than > or = 7 cm) with overall survival (P = 0.002) and MFS (P = 0.002), N-stage (N0 better than N1) with overall survival (P = 0.004) and MFS (P < 0.001), and UICC-stage (stage II better than III) with overall survival (P = 0.025) and MFS (P = 0.010). On multivariate analysis, haemoglobin levels during radio-chemotherapy maintained significance for overall survival (P = 0.002) and locoregional control (P < 0.001), tumour length for overall survival (P = 0.002) and MFS (P = 0.008), and N-stage for MFS (P = 0.003).

CONCLUSIONS

Haemoglobin during radiotherapy and concurrent radio-chemotherapy is an independent prognostic factor in oesophageal cancer treatment. To improve outcome, it seems important to maintain the haemoglobin at 12-14 g/dl.

Carbonic anhydrase IX expression and tumor oxygenation status do not correlate at the microregional level in locally advanced cancers of the uterine cervix

PURPOSE

Carbonic anhydrase IX (CA IX) can be induced by hypoxia in vitro and shows an immunohistochemical expression pattern that is predominantly found in perinecrotic tumor areas and correlates with exogenous markers of hypoxia, such as pimonidazole. CA IX might therefore serve as an endogenous marker of tumor hypoxia, although comparisons of CA IX immunostaining with direct oxygenation measurements using pO2 microsensors have thus far yielded contradictory results.

EXPERIMENTAL DESIGN

Because tumor heterogeneity may be among the factors responsible for the discrepancy between the two methods, CA IX expression in tissue samples originating from oxygen microelectrode tracks of locally advanced cervical cancers was assessed in this study. Seventy-seven biopsy specimens were analyzed immunohistochemically using an anti-CA IX rabbit polyclonal antibody and semiquantitative scoring.

RESULTS

CA IX expression showed no correlation with the oxygenation variables median pO2 and hypoxic fraction 2.5, 5, or 10. Cases with higher International Federation of Gynecology and Obstetrics stages (IIb-IVa) exhibited stronger expression of CA IX (P = 0.035) and CA IX expression tended to be more prevalent in node-positive patients (P = 0.051).

CONCLUSIONS

These data indicate that CA IX cannot be recommended as a substitute for oxygen microelectrode measurements. That the expression of CA IX does not correlate with the oxygenation status may be due to the degree to which other factors, such as nutrient (e.g., glucose) deficiency or the action of oncogenic mutations, can modulate the in vivo expression of this protein, rendering a strict association with tumor hypoxia too unreliable for clinical use.

Oxygen-modifying treatment with ARCON reduces the prognostic significance of hemoglobin in squamous cell carcinoma of the head and neck

PURPOSE

To evaluate the prognostic significance of hemoglobin (Hb) levels measured before and during treatment with accelerated radiotherapy with carbogen and nicotinamide (ARCON).

METHODS AND MATERIALS

Two hundred fifteen patients with locally advanced tumors of the head and neck were included in a phase II trial of ARCON. This treatment regimen combines accelerated radiotherapy for reduction of repopulation with carbogen breathing and nicotinamide to reduce hypoxia. In these patients, Hb levels were measured before, during, and after radiotherapy.

RESULTS

Preirradiation and postirradiation Hb levels were available for 206 and 195 patients respectively. Hb levels below normal were most frequently seen among patients with T4 (p < 0.001) and N2 (p < 0.01) disease. Patients with a larynx tumor had significantly higher Hb levels (p < 0.01) than other tumor sites. During radiotherapy, 69 patients experienced a decrease in Hb level. In a multivariate analysis there was no prognostic impact of Hb level on locoregional control, disease-free survival, and overall survival. Primary tumor site was independently prognostic for locoregional control (p = 0.018), and gender was the only prognostic factor for disease-free and overall survival (p < 0.05). High locoregional control rates were obtained for tumors of the larynx (77%) and oropharynx (72%).

CONCLUSION

Hemoglobin level was not found to be of prognostic significance for outcome in patients with squamous cell carcinoma of the head and neck after oxygen-modifying treatment with ARCON.

Plasma osteopontin, hypoxia, and response to the hypoxia sensitiser nimorazole in radiotherapy of head and neck cancer: results from the DAHANCA 5 randomised double-blind placebo-controlled trial

BACKGROUND

The concentration of osteopontin (SPP1) in plasma is associated with tumour hypoxia. The DAHANCA 5 trial found that the hypoxia radiosensitiser nimorazole significantly improved the outcome of radiotherapy for patients with head and neck cancer compared with placebo. However, whether all patients benefit from such modification of hypoxia is unclear. We aimed to assess whether the concentration of plasma osteopontin could predict response to the hypoxia radiosensitiser.

METHODS

Plasma concentrations of osteopontin were measured by use of ELISA from stored samples of 320 patients randomised in the DAHANCA 5 trial. Samples were grouped into tertiles according to high (167-1382 microg/L), intermediate (69-166 microg/L), or low (0-68 microg/L) concentrations of plasma osteopontin, and analysed for locoregional tumour control and disease-specific survival at 5 years.

FINDINGS

Overall, locoregional tumour failure and disease-specific mortality were more frequent in patients assigned placebo than in those assigned nimorazole (relative risk [RR] 0.51 [95% CI 0.32-0.79] and 0.54 [0.35-0.85], respectively). Locoregional tumour failure was more frequent in patients with high concentrations of osteopontin assigned placebo than in those with high concentrations assigned nimorazole (0.19 [0.08-0.44]), as was disease-specific mortality (0.25 [0.11-0.59]). However, neither locoregional tumour failure nor disease-specific mortality differed between groups for patients with low concentrations of plasma osteopontin (0.79 [0.26-1.70]) and (0.69 [0.31-1.51]) or for those with intermediate concentrations (0.90 [0.41-1.98] and 0.89 [0.41-1.96], respectively).

INTERPRETATION

High plasma concentrations of osteopontin are associated with a poor outlook after radiotherapy for patients with head and neck cancer, but can be improved by use of nimorazole. High concentrations of osteopontin can predict clinically relevant hypoxia, and might identify patients who will benefit from modification of hypoxia during radiotherapy.

Prognostic value of tumor oxygenation in 397 head and neck tumors after primary radiation therapy. An international multi-center study

PURPOSE

To analyze the relationship between pre-treatment measurements of tumor oxygen tension (pO2) and survival in advanced head and neck cancer.

PATIENTS AND METHODS

Eppendorf pO2 measurements in 397 patients from seven centers were analyzed using the fraction of pO2 values < or =2.5 mmHg (HP2.5), < or =5 mmHg (HP5) and median tumor pO2 (mmHg) as descriptors. All patients had intended curative radiation therapy alone or as pre- or post-operative radiotherapy or radio-chemotherapy according to the practice at each center.

RESULTS

The degree of hypoxia varied between tumors with an overall median tumor pO2=9 mmHg (range 0-62 mmHg), a median HP2.5=19% (range 0-97%) and HP5=38%, (range 0-100%). By quadratic regression median tumor pO2 correlated with Hb (2P=0.026, n=357), while HP2.5 or HP5 did not. HP2.5 above the population median was the only parameter that associated with poor overall survival (Kaplan Meier analysis, P=0.006). In a multivariate Cox Proportional Hazards analysis, stratified according to institution HP2.5 was by far the most statistically significant factor in explaining the variability in survival. After adjusting for HP2.5, clinical stage, radiation dose and surgery hemoglobin concentration was not significant in the model. The prognostic model shows that the 5-year survival is almost constant for HP2.5 values in the range from 0 to 20%, whereas the 5-year survival approaches 0% in the most hypoxic tumors.

CONCLUSION

This study provides evidence that tumor hypoxia is associated with a poor prognosis in patients with advanced head and neck cancer.

Novel therapeutic targets in squamous cell carcinoma of the head and neck

The treatment of squamous cell carcinoma of the head and neck (SCCHN) has recently witnessed the introduction of molecularly targeted agents based on disease biology, target discovery, and validation. One class of agents, the epidermal growth factor receptor (EGFR) inhibitors, is currently in phase III trials. There are multiple processes, however, that appear to be suitable for targeted therapy beyond EGFR. These include signal transduction, cell cycle control, prostaglandin synthesis, protein degradation, hypoxia, and angiogenesis. These systems and specific protein targets will be reviewed in detail with emphasis on promising preclinical and early clinical evidence of activity.