Microenvironmental adaptation of experimental tumours to chronic vs acute hypoxia

Strategies of Alleviating Tumor Hypoxia and Enhancing Tumor Therapeutic Effect by Macromolecular Nanomaterials

Hypoxia as one of the most prominent features in tumors, has presented negative effects on tumor therapies including photodynamic therapy, radiotherapy, and chemotherapies, leading to the tumor regeneration and metastasis. Recently, nanomedicines have been proposed to handle the hypoxia dilemma. Some nanomedicines alleviated hypoxia to enhance the therapeutic effect, others used hypoxia-sensitive substances to treat tumor. Among them, macromolecular nanomaterials-based nanomedicine has attracted increased research interest. However, the complicated tumor microenvironment disturbs the practical application of macromolecular nanomaterials to deal with hypoxia. This review highlights the influence of hypoxia on tumor therapy and some new strategies of using macromolecular nanomaterials to overcome hypoxia for effective tumor therapy.

Glucose Oxidase-Instructed Traceable Self-Oxygenation/Hyperthermia Dually Enhanced Cancer Starvation Therapy

Cancer theranostics based on glucose oxidase (GOx)-induced starvation therapy has got more and more attention in cancer management. Herein, GOx armed manganese dioxide nanosheets (denoted as MNS-GOx) were developed as cancer nanotheranostic agent for magnetic resonance (MR)/photoacoustic (PA) dual-modal imaging guided self-oxygenation/hyperthermia dually enhanced starvation cancer therapy. The manganese dioxide nanomaterials with different morphologies (such as nanoflowers, nanosheets and nanowires) were synthesized by a biomimetic approach using melanin as a biotemplate. Afterwards, the manganese dioxide nanosheets (MNS) with two sides and large surface area were selected as the vehicle to carry and deliver GOx. The as-prepared MNS-GOx can perform the circular reaction of glucose oxidation and H2O2 decomposition for enhanced starvation therapy. Moreover, the catalytic activity of GOx could be further improved by the hyperthermia of MNS-GOx upon near-infrared laser irradiation. Most intriguingly, MNS-GOx could achieve "turn-on" MR imaging and "turn-off" PA imaging simultaneously. The theranostic capability of MNS-GOx was evaluated on A375 tumor-bearing mice with all tumor elimination. Our findings integrated molecular imaging and starvation-based synergistic cancer therapy, which provided a new platform for cancer nanotheranostics.

Modulating Hypoxia via Nanomaterials Chemistry for Efficient Treatment of Solid Tumors

The common existence of hypoxia in solid tumors has been heavily researched because it renders tumors more resistant to most standard therapeutic methods, such as radiotherapy (RT), chemotherapy, and photodynamic therapy (PDT), and is associated with a more malignant phenotype and poor survival in patients with tumors. The development of hypoxia modulation methods for advanced therapeutic activity is therefore of great interest but remains a considerable challenge. Since the significant development of nanotechnology and nanomedicine, functionalized nanomaterials can be exploited as adjuvant "drugs" for these oxygen-dependent standard therapies or as hypoxia initiators for advanced new therapies to solid tumors. In this Account, we summarize our recent studies on the design and synthesis of nanomaterials with a set of desired chemistry benefits achievable by modulating hypoxia, suggesting a valid therapeutic option for tumors. The investigated strategies can be categorized into three groups: The first strategy is based on countering hypoxia. Considering that O₂ deficiency is the major obstacle for the oxygen-dependent therapies, we initially developed methods to supply O₂ by taking advantage of the hypoxia-responsive properties of nano-MnO₂ or nanomaterials' photothermal effects for increased intratumoral blood flow. The second approach is to disregard hypoxia. Possible benefits of nanoagents include reducing/eliminating reliance on O₂ or making O₂ replacements as adjuvants to standard therapies. To this end, we investigated a nano-upconversion/scintillator with the capacity toup-/down-convert near-infrared light (NIR)/X-ray to luminescence in the ultraviolet/visible region fortype-I PDT with minimized oxygen-tension dependency or developed Fe-based nanomaterials for chemodynamic therapy (CDT) without external energy and oxygen participation for efficient free radical killing of deep tumors. The third strategy involves exploiting hypoxia. The unique biological characteristics of hypoxia are exploited to activate nanoagents for new therapies. To address the discrepancy between the nanoagents' demand and supply within the hypoxia region, a smart "molecule-nano" medicine that stays small-molecule-like in the bloodstream and turns into self-assembled nanovesicles after entry into the hypoxia region was constructed for hypoxia-adaptive photothermal therapy (PTT). In addition to traditional anti-angiogenesis therapy, we prepared Mg₂Si nanoparticles by a special self-propagating high-temperature synthesis approach. These nanoparticles can directly remove the intratumoral oxygen via the oxidation reactions of Mg₂Si and later efficiently block the rapid reoxygenation via tumor blood vessels by the resultant SiO₂ microsheets for cancer starvation therapy. Taken together, these findings indicate that nanomaterials will assume a valuable role for anticancer exploration based on either their properties to make up oxygen deficiency or the use of hypoxia for therapeutic applications.

Cell type-dependent HIF1 α-mediated effects of hypoxia on proliferation, migration and metastatic potential of human tumor cells

Tumor hypoxia promotes neoangiogenesis and contributes to the radio- and chemotherapy resistant and aggressive phenotype of cancer cells. However, the migratory response of tumor cells and the role of small GTPases regulating the organization of cytoskeleton under hypoxic conditions have yet to be established. Accordingly, we measured the proliferation, migration, RhoA activation, the mRNA and protein levels of hypoxia inducible factor-1alpha (HIF-1α) and three small G-proteins, Rac1, cdc42 and RhoA in a panel of five human tumor cell lines under normoxic and hypoxic conditions. Importantly, HT168-M1 human melanoma cells with high baseline migration capacity showed increased HIF-1α and small GTPases expression, RhoA activation and migration under hypoxia. These activities were blocked by anti- HIF-1α shRNA. Moreover, the in vivo metastatic potential was promoted by hypoxia mimicking CoCl₂ treatment and reduced upon inhibition of HIF-1α in a spleen to liver colonization experiment. In contrast, HT29 human colon cancer cells with low migration capacity showed limited response to in vitro hypoxia. The expression of the small G-proteins decreased both at mRNA and protein levels and the RhoA activation was reduced. Nevertheless, the number of lung or liver metastatic colonies disseminating from orthotopic HT29 grafts did not change upon CoCl₂ or chetomin treatment. Our data demonstrates that the hypoxic environment induces cell-type dependent changes in the levels and activation of small GTPases and results in varying migratory and metastasis promoting responses in different human tumor cell lines.

Chlorogenic acid inhibits hypoxia-induced angiogenesis via down-regulation of the HIF-1α/AKT pathway

BACKGROUND

The hypoxia-inducible factor-1 (HIF-1) is known to play an important role in cellular responses to hypoxia, including the transcriptional activation of a number of genes involved in tumor angiogenesis. Chlorogenic acid (CGA), one of the most abundant polyphenols in the human diet, has been reported to inhibit cancer cell growth. The effect of CGA on tumor angiogenesis and its underlying mechanisms are, as yet, unknown.

METHODS

The effect of CGA on HIF-1α expression was assessed by Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) assays in A549 lung cancer cells. The transcriptional activity of the HIF-1 complex was confirmed using a luciferase assay. To assess whether angiogenic factors are increased under hypoxic conditions in these cells, vascular endothelial growth factor (VEGF) expression levels were measured by RT-PCR and Western blotting. The direct effect of CGA on human vascular endothelial cells (HUVEC) under hypoxic conditions was analyzed using in vitro assays, including tube-formation, wound healing and Transwell invasion assays. To investigate the effect of CGA on angiogenesis in vivo, we performed a Matrigel plug assay in a mouse model. Finally, the effect of CGA on AKT and ERK activation (phosphorylation) as a putative mechanism underlying the effect of CGA on VEGF-mediated angiogenesis inhibition was assessed using Western blotting.

RESULTS

We found that CGA significantly decreases the hypoxia-induced HIF-1α protein level in A549 cells, without changing its mRNA level. CGA was, however, found to suppress the transcriptional activity of HIF-1α under hypoxic conditions, leading to a decrease in the expression of its downstream target VEGF. We also found that CGA can block hypoxia-stimulated angiogenesis in vitro and VEGF-stimulated angiogenesis in vivo using HUVEC cells. In addition, we found that CGA can inhibit the HIF-1α/AKT signaling pathway, which plays an important role in VEGF activation and angiogenesis.

CONCLUSIONS

Our data indicate that CGA plays a role in the suppression of angiogenesis via inhibition of the HIF-1α/AKT pathway. CGA may represent a novel therapeutic option for the treatment of (lung) cancer.

Probing hypoxia-induced staurosporine resistance in prostate cancer cells with a microfluidic culture system

A microfluidic system for cell culture and drug response studies was developed to elucidate the effects of hypoxia on drug susceptibility. Drug response studies were performed in prostate cancer cells and Ramos B cells under normoxic and hypoxic conditions. A vacuum actuated microfluidic culture device was used for cell culture and PC3 cells were cultured in the chip up to 16 hours. Cells were treated with several concentrations of staurosporine and apoptosis was assayed using the fluorescent probes MitoTracker Deep Red and Annexin-V. For hypoxic samples, the chip was placed in a hypoxia chamber and pre-conditioned at <1% oxygen before inducing the cells with staurosporine. Cells exposed to 2 μM staurosporine were 32% ± 10% apoptotic under normoxic conditions but only 1.5% ± 12% apoptotic under hypoxic conditions. As little as 1 hour of hypoxic preconditioning increased drug resistance. Cell apoptosis correlated with drug dose, although in each case hypoxia reduced the apoptotic fraction significantly. Given the rapid nature of cell adaptation to hypoxia, this chip and analysis approach can be used to identify compounds that can induce cell death in hypoxic tumor cells rapidly.

PET imaging of the impact of extracellular pH and MAP kinases on the p-glycoprotein (Pgp) activity

The functional activity of p-glycoprotein (Pgp) can be increased in vitro by an extracellular acidosis via activation of MAP kinases (p38, ERK1/2). In order to study these effects in vivo a new (68)Ga-labeled PET tracer was developed which serves as a substrate of the Pgp and therefore indirectly mirrors the Pgp activity. For in vivo studies, experimental tumors were imaged under acidic conditions (inspiratory hypoxia, injection of lactic acid) and during inhibition of MAP kinases in a μ-PET system. In vitro, [(68)Ga]MFL6.MZ showed an accumulation within the cells of about 20% which was increased to 30% by Pgp inhibition. In solid tumors a marked tracer uptake was observed showing spatial heterogeneity. When the tumors were acidified, the PET tracer accumulation was reduced by 20-30%. Changing the inspiratory O(2)-fraction to 8% led dynamically to a decrease in pH and in parallel to a reduced tracer concentration. Inhibition of the p38 pathway reduced the Pgp transport rate. The new (68)Ga-labeled tracer is suitable for PET imaging of the tissue Pgp activity. In vivo imaging reveals that an acidosis activates the Pgp markedly, a mechanism in which the p38-MAPK pathway seems to play an important role.

Acute versus chronic hypoxia in tumors: Controversial data concerning time frames and biological consequences

BACKGROUND

Many tumors contain hypoxic regions. Hypoxia, in turn, is known to increase aggressiveness and to be associated with treatment resistance. The two most frequently described and investigated subtypes of tumor hypoxia are acute and chronic. These two subtypes can lead to completely different hypoxia-related responses within the tumor, which could have a direct effect on tumor development and response to treatment. In order to accurately assess the specific biological consequences, it is important to understand which time frames best define acute and chronic hypoxia.

MATERIALS AND METHODS

This article provides an overview of the kinetics of in vitro and in vivo acute and chronic tumor hypoxia. Special attention was paid to differentiate between methods to detect spontaneous in vivo hypoxia and to describe the biological effects of experimental in vitro and in vivo acute and chronic tumor hypoxia.

RESULTS AND CONCLUSIONS

There are large variations in reported spontaneous fluctuations in acute hypoxia that are dependent on the cell lines investigated and the detection method used. In addition to differing hypoxia levels, exposure times used to induce in vitro and in vivo experimental acute and chronic hypoxia range from 30 min to several weeks with no clear boundaries separating the two. Evaluation of the biological consequences of each hypoxia subtype revealed a general trend that acute hypoxia leads to a more aggressive phenotype. Importantly, more information on the occurrence of acute and chronic hypoxia in human tumors is needed to help our understanding of the clinical consequences.

Impact of hypoxia on the metastatic potential of human prostate cancer cells

PURPOSE

Intratumoral hypoxia is known to be associated with radioresistance and metastasis. The present study examined the effect of acute and chronic hypoxia on the metastatic potential of prostate cancer PC-3, DU145, and LNCaP cells.

METHODS AND MATERIALS

Cell proliferation and clonogenicity were tested by MTT assay and colony formation assay, respectively. "Wound-healing" and Matrigel-based chamber assays were used to monitor cell motility and invasion. Hypoxia-inducible factor 1 alpha (HIF-1α) expression was tested by Western blot, and HIF-1-target gene expression was detected by real-time polymerase chain reaction. Secretion of matrix metalloproteinases (MMPs) was determined by gelatin zymography.

RESULTS

When PC-3 cells were exposed to 1% oxygen (hypoxia) for various periods of time, chronic hypoxia (≥24 h) decreased cell proliferation and induced cell death. In contrast, prostate cancer cells exposed to acute hypoxia (≤6 h) displayed increased motility, clonogenic survival, and invasive capacity. At the molecular level, both hypoxia and anoxia transiently stabilized HIF-1α. Exposure to hypoxia also induced the early expression of MMP-2, an invasiveness-related gene. Treatment with the HIF-1 inhibitor YC-1 attenuated the acute hypoxia-induced migration, invasion, and MMP-2 activity.

CONCLUSIONS

The length of oxygen deprivation strongly affected the functional behavior of all three prostate cancer cell lines. Acute hypoxia in particular was found to promote a more aggressive metastatic phenotype.

Small animal tumour imaging with MRI and the ECAT EXACT scanner: application of partial volume correction and comparison with microPET data

OBJECTIVE

Partial volume effects caused by limited spatial resolution of conventional positron emission tomography (PET) scanners result in an underestimation of the activity concentration in small tumours. The aim of the study was to evaluate the feasibility of small animal tumour imaging with the clinical PET scanner ECAT EXACT after partial volume correction based on MRI calculations. The same tumour model was examined additionally with the small animal PET system, microPET focus 120.

METHODS

Before the ECAT EXACT studies recovery coefficients for different sphere volumes were generated with phantom experiments. For the following in-vivo study DS-sarcoma cells were implanted on both hind foot dorsum of male Sprague-Dawley rats. In-vivo tumour volume calculations were done with the high-resolution MRI system, Magnetom Vision Experimental. Dynamic F-fluorodeoxyglucose (FDG) PET was performed with the scanner ECAT EXACT (5 MBq intravenous, two-dimensional mode, n = 16 tumours) or with the microPET focus 120 (20 MBq intravenous, two-dimensional mode, n = 10 tumours). The animals were then killed, the tumours rapidly explanted, weighed and homogenized. The concentration of F-FDG was measured with a gamma counter and decay corrected; the ex-vivo F-FDG concentration was compared with the mean tumour activity concentration of the PET data.

RESULTS

Using the ECAT EXACT mean underestimation of actual tumour F-FDG concentration was 35.4%, for partial volume-corrected data this error decreased to 1.7%. In addition, after partial volume correction congruence and linear correlation between the regions of interest-based activity concentration and ex-vivo measurements were excellent (r = 0.98). These results were quite similar to the microPET experiments without partial volume correction: r = 0.99.

CONCLUSION

These data indicate that partial volume correction might allow use of the clinical PET system, ECAT EXACT, for the metabolic assessment of small animal tumours >/=10 mm with sufficient accuracy if no dedicated animal PET is available.

Activation of P-glycoprotein (Pgp)-mediated drug efflux by extracellular acidosis: in vivo imaging with 68Ga-labelled PET tracer

PURPOSE

In vitro it has been shown that the functional activity of P-glycoprotein (Pgp), an important drug transporter responsible for multidrug resistance, can be strongly increased by extracellular acidosis. Here mitogen-activated protein kinases (MAPK) (p38, ERK1/2) seem to play an important role for signal transduction. However, it is unclear whether these effects are also relevant in vivo.

METHODS

With the newly developed PET tracer Schiff base-based (68)Ga-MFL6.MZ the functional Pgp activity was visualized under acidic conditions and during inhibition of MAPKs non-invasively by means of microPET in rat tumours. Tumours were acidified either by inspiratory hypoxia (8% O(2)) or by injection of lactic acid. Inhibitors of the MAPK were injected intratumourally.

RESULTS

With increasing tumour volume the tumour pH changed from 7.0 to 6.7 and simultaneously the Pgp activity increased almost linearly. When the tumour was acidified by direct lactic acid injection the PET tracer uptake was reduced by 20% indicating a higher transport rate out of the cells. Changing the inspiratory O(2) fraction to 8% dynamically led to a reduction of extracellular pH and in parallel to a decrease of tracer concentration. While inhibition of the p38 pathway reduced the Pgp transport rate, inhibition of ERK1/2 had practically no impact.

CONCLUSION

An acidic extracellular environment significantly stimulates the Pgp activity. The p38 MAPK pathway plays an important role for Pgp regulation in vivo, whereas ERK1/2 is of minor importance. From these results new strategies for overcoming multidrug resistance (e.g. reducing tumour acidosis, inhibition of p38) may be developed.

The role of hypoxia in recurrence following resection of Dukes' B colorectal cancer

GOALS

Tumour hypoxia has been shown to be a predictor of early distant relapse in node-negative breast and cervical cancer. The purpose of the present study was to determine the role of hypoxia in predicting patients who are at high risk of disease recurrence in Dukes B colorectal cancers.

MATERIALS AND METHODS

Archival tissue was retrieved from 52 patients who had undergone surgical resection for primary colorectal cancer. Tissue micro-arrays were constructed using tissue from the margin and the centre of the tumour. Hypoxia markers hypoxia-inducible factor (Hif)-1 alpha, vascular endothelial growth factor (VEGF), carbonic anhydrase (CA)-9 and glucose transporter (Glut)-1 were visualised using immunohistochemical detection and quantified using semi-quantitative analysis of the digitised images. Clinical details and outcome data were retrieved by case note review and collated with hypoxia markers data in a statistical database.

RESULTS

Primary colorectal cancers with a high Hif-1 alpha expression tended to have a significantly worse disease-free survival (log rank p < 0.001) and overall survival (log rank p = 0.012). VEGF was also a significant predictor of disease recurrence in primary colorectal cancers (p = 0.015). Significant correlations were also noted between Hif-1 alpha and VEGF (Pearson's p = 0.009). Glut-1 and CA-9 did not show a similar pattern with no differences in the expression pattern and no correlation observed with any of the markers. Multivariate analysis of prognostic factors showed vascular invasion (p < 0.001) and Hif-1 alpha at the tumour margin (p < 0.001) to be independent predictors for the development of liver metastases.

CONCLUSION

These results suggest an important role for Hif-1 alpha and VEGF in colorectal cancer progression, with both markers biological mechanisms directly interlinked through the hypoxic pathway. Identification of high-risk patients using the above factors will improve treatment strategies in node-negative disease and help improve patient outcome.

Hyperoxia retards growth and induces apoptosis, changes in vascular density and gene expression in transplanted gliomas in nude rats

This study describes the biological effects of hyperoxic treatment on BT4C rat glioma xenografts in vivo with special reference to tumor growth, angiogenesis, apoptosis, general morphology and gene expression parameters. One group of tumor bearing animals was exposed to normobaric hyperoxia (1 bar, pO(2) = 1.0) and another group was exposed to hyperbaric hyperoxia (2 bar, pO(2) = 2.0), whereas animals housed under normal atmosphere (1 bar, pO(2) = 0.2) served as controls. All treatments were performed at day 1, 4 and 7 for 90 min. Treatment effects were determined by assessment of tumor growth, vascular morphology (immunostaining for von Willebrand factor), apoptosis by TUNEL staining and cell proliferation by Ki67 staining. Moreover, gene expression profiles were obtained and verified by real time quantitative PCR. Hyperoxic treatment caused a approximately 60% reduction in tumor growth compared to the control group after 9 days (p < 0.01). Light microscopy showed that the tumors exposed to hyperoxia contained large "empty spaces" within the tumor mass. Moreover, hyperoxia induced a significant increase in the fraction of apoptotic cells ( approximately 21%), with no significant change in cell proliferation. After 2 bar treatment, the mean vascular density was reduced in the central parts of the tumors compared to the control and 1 bar group. The vessel diameters were significantly reduced (11-24%) in both parts of the tumor tissue. Evidence of induced cell death and reduced angiogenesis was reflected by gene expression analyses.Increased pO(2)-levels in experimental gliomas, using normobaric and moderate hyperbaric oxygen therapy, caused a significant reduction in tumor growth. This process is characterized by enhanced cell death, reduced vascular density and changes in gene expression corresponding to these effects.

Hyperoxia retards growth and induces apoptosis and loss of glands and blood vessels in DMBA-induced rat mammary tumors

Background

This study investigated the effects of hyperoxic treatment on growth, angiogenesis, apoptosis, general morphology and gene expression in DMBA-induced rat mammary tumors.

Methods

One group of animals was exposed to normobaric hyperoxia (1 bar, pO₂ = 1.0 bar) and another group was exposed to hyperbaric hyperoxia (1.5 bar, pO₂ = 1.5 bar). A third group was treated with the commonly used chemotherapeutic drug 5- Fluorouracil (5-FU), whereas animals housed under normal atmosphere (1 bar, pO₂ = 0.2 bar) served as controls. All treatments were performed on day 1, 4, 7 and 10 for 90 min. Tumor growth was calculated from caliper measurements. Biological effects of the treatment, was determined by assessment of vascular morphology (immunostaining for von Willebrandt factor) and apoptosis (TUNEL staining). Detailed gene expression profiles were obtained and verified by quantitative rtPCR.

Results

Tumor growth was significantly reduced (~57–66 %) after hyperoxic treatment compared to control and even more than 5-FU (~36 %). Light microscopic observations of the tumor tissue showed large empty spaces within the tissue after hyperoxic treatment, probably due to loss of glands as indicated by a strong down-regulation of glandular secretory proteins. A significant reduction in mean vascular density (30–50%) was found after hyperoxic treatment. Furthermore, increased apoptosis (18–21%) was found after hyperoxic treatment.

Conclusion

Thus, by increasing the pO₂ in mammary tumor tissue using normobaric and moderate hyperbaric oxygen therapy, a significant retardation in tumor growth is achieved, by loss of glands, reduction in vascular density and enhanced cell death. Hyperbaric oxygen should therefore be further evaluated as a tumor treatment.

Physiological oxygenation status is required for fully differentiated phenotype in kidney cortex proximal tubules

Hypoxia has been suspected to trigger transdifferentiation of renal tubular cells into myofibroblasts in an epithelial-to-mesenchymal transition (EMT) process. To determine the functional networks potentially altered by hypoxia, rat renal tubule suspensions were incubated under three conditions of oxygenation ranging from normoxia (lactate uptake) to severe hypoxia (lactate production). Transcriptome changes after 4 h were analyzed on a high scale by restriction fragment differential display. Among 1,533 transcripts found, 42% were maximally expressed under severe hypoxia and 8% under mild hypoxia (Po2 = 48 mmHg), suggesting two different levels of oxygen sensing. Normoxia was required for full expression of the proximal tubule-specific transcripts 25-hydroxyvitamin D 1-hydroxylase ( Cyp27b1) and l-pyruvate kinase ( Pklr), transcripts involved in tissue cohesion such as fibronectin ( Fn1) and N-cadherin ( Cdh2), and non-muscle-type myosin transcripts. Mild hypoxia increased myogenin transcript level. Conversely, severe hypoxia increased transcripts involved in extracellular matrix remodeling, those of muscle-type myosins, and others involved in creatine phosphate synthesis and lactate transport ( Slc16a7). Accordingly, microscopy showed loss of tubule aggregation under hypoxia, without tubular disruption. Hypoxia also increased the levels of kidney-specific transcripts normally restricted to the less oxygenated medullary zone and others specific for the distal part of the nephron. We conclude that extensive oxygen supply to the kidney tubule favors expression of its differentiated functions specifically in the proximal tubule, whose embryonic origin is mesenchymal. The phenotype changes could potentially permit transient adaptation to hypoxia but also favor pathological processes such as tissue invasion.

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.