Lack of prognostic and predictive value of CA IX in radiotherapy of squamous cell carcinoma of the head and neck with known modifiable hypoxia: An evaluation of the DAHANCA 5 study

Understanding metabolic alterations and heterogeneity in cancer progression through validated immunodetection of key molecular components: a case of carbonic anhydrase IX

Cancer metabolic heterogeneity develops in response to both intrinsic factors (mutations leading to activation of oncogenic pathways) and extrinsic factors (physiological and molecular signals from the extracellular milieu). Here we review causes and consequences of metabolic alterations in cancer cells with focus on hypoxia and acidosis, and with particular attention to carbonic anhydrase IX (CA IX). CA IX is a cancer-associated enzyme induced and activated by hypoxia in a broad range of tumor types, where it participates in pH regulation as well as in molecular mechanisms supporting cancer cells’ invasion and metastasis. CA IX catalyzes reversible conversion of carbon dioxide to bicarbonate ion plus proton and cooperates with a spectrum of molecules transporting ions or metabolites across the plasma membrane. Thereby CA IX contributes to extracellular acidosis as well as to buffering intracellular pH, which is essential for cell survival, metabolic performance, and proliferation of cancer cells. Since CA IX expression pattern reflects gradients of oxygen, pH, and other intratumoral factors, we use it as a paradigm to discuss an impact of antibody quality and research material on investigating metabolic reprogramming of tumor tissue. Based on the validation, we propose the most reliable CA IX-specific antibodies and suggest conditions for faithful immunohistochemical analysis of molecules contributing to heterogeneity in cancer progression.

Hypoxia induces radioresistance, epithelial‑mesenchymal transition, cancer stem cell‑like phenotype and changes in genes possessing multiple biological functions in head and neck squamous cell carcinoma

Hypoxia has been linked with increased resistance to treatment in various solid tumors, including head and neck squamous cell carcinoma (HNSCC). The aim of the present study was to identify genes involved in hypoxia‑mediated responses to radiotherapy in HNSCC. A total of three HNSCC cell lines with an epithelial phenotype were selected for this study and cultured under normoxic (21% O₂) or hypoxic (1% O₂) conditions. The sensitivity of the HNSCC cells to radiotherapy was assessed by a crystal violet assay. Western blotting (for protein expression), cDNA microarrays and reverse transcription‑quantitative PCR (for gene expression) were also applied. Small interfering RNA silencing was used to knock down target genes. The results revealed that hypoxia negatively affected the response of HNSCC cells to radiotherapy. Of note, increased levels of N‑cadherin, vimentin and fibronectin, as well as stem cell‑associated transcription factors, were observed under hypoxia. The microarray analysis revealed a number of hypoxia‑regulated genes that were involved in multiple biological functions. However, downregulation of hypoxia‑regulated genes did not affect sensitivity to radiotherapy of the investigated cell lines. Taken together, the present findings indicated several important pathways and genes that were involved in hypoxia and radiotherapy resistance. It is hypothesized that panels of reported hypoxia‑regulated genes may be useful for the prediction of radiotherapy responses in patients with HNSCC.

Immunohistochemistry-based hypoxia-immune prognostic classifier for head-and-neck cancer patients undergoing chemoradiation - Post-hoc analysis from a prospective imaging trial

PURPOSE

As both tumor hypoxia and an immunosuppressing tumor microenvironment hamper the anti-tumor activity of radiotherapy in head-and-neck squamous cell carcinoma (HNSCC), we aimed to develop an immunohistochemistry-based hypoxia-immune classifier.

METHODS

39 patients receiving definitive chemoradiation for HNSCC within a prospective trial were included in this analysis. Baseline tumor samples were analyzed for the hypoxia marker carbonic anhydrase IX (CAIX) and tumor-infiltrating lymphocytes (TILs) and were correlated with [18F]-misonidazole ([18F]FMISO) PET measurements. The impact of the biomarkers on the locoregional control (LRC) was examined using Cox analyses and concordance index statistics.

RESULTS

Low CAIX (HR = 0.352, 95%CI 0.124-1.001, p = 0.050) and high TIL levels (HR = 0.308, 95%CI 0.114-0.828, p = 0.020) were independent parameters for improved LRC and did not correlate with each other (Spearman's ρ = 0.034, p = 0.846). Harrell's C was 0.66 for CAIX and TIL levels alone and 0.71 for the combination. 2-year LRC was 73%, 62% and 11% for the prognostically good (CAIX_low/TIL_high), intermediate (CAIX_low/TIL_low or CAIX_high/TIL_high) and poor groups (CAIX_high/TIL_low), respectively (p = 0.001). Focusing on T lymphocytes, the hypoxia-immune classifier could still stratify between favorable (CAIX_low/CD3 + TIL_high), intermediate (CAIX_low/CD3 + TIL_low or CAIX_high/CD3 + TIL_high) and poor subgroups (CAIX_high/CD3 + TIL_low) with a 2-year LRC of 80%, 59% and 14%, respectively (p = 0.001). There was a positive correlation between baseline CAIX levels and [18F]FMISO SUV in week 2 of chemoradiation (ρ = 0.324, p = 0.050), indicating an association between higher baseline CAIX expression and tumor hypoxia persistence.

CONCLUSION

We developed a clinically feasible hypoxia-immune prognostic classifier for HNSCC patients based on pre-treatment immunohistochemistry. However, external validation is required to determine the prognostic value and the potential usage for personalized radiation oncology.

[18F]-HX4 PET/CT hypoxia in patients with squamous cell carcinoma of the head and neck treated with chemoradiotherapy: Prognostic results from two prospective trials

Introduction

The presence of hypoxia in head-and-neck squamous cell carcinoma is a negative prognostic factor. PET imaging with [18F] HX4 can be used to visualize hypoxia, but it is currently unknown how this correlates with prognosis. We investigated the prognostic value of [18F] HX4 PET imaging in patients treated with definitive radio(chemo)therapy (RTx).

Materials and methods

We analyzed 34 patients included in two prospective clinical trials (NCT01347281, NCT01504815). Static [18F] HX4 PET-CT images were collected, both pre-treatment (median 4 days before start RTx, range 1-16), as well as during RTx (median 13 days after start RTx, range 3-17 days). Static uptake at both time points (n = 33 pretreatment, n = 28 during RTx) and measured changes in hypoxic fraction (HF) and hypoxic volume (HV) (n = 27 with 2 time points) were analyzed. Univariate cox analyses were done for local progression free survival (PFS) and overall survival (OS) at both timepoints. Change in uptake was analyzed by comparing outcome with Kaplan-Meier curves and log-rank test between patients with increased and decreased/stable hypoxia, similarly between patients with and without residual hypoxia (rHV = ratio week 2/baseline HV with cutoff 0.2). Voxelwise Spearman correlation coefficients were calculated between normalized [18F] HX4 PET uptake at baseline and week 2.

Results

Analyses of static images showed no prognostic value for [18F] HX4 uptake. Analysis of dynamic changes showed that both OS and local PFS were significantly shorter (log-rank P < 0.05) in patients with an increase in HV during RTx and OS was significantly shorter in patients with rHV, with no correlation to HPV-status. The voxel-based correlation to evaluate spatial distribution yielded a median Spearman correlation coefficient of 0.45 (range 0.11-0.65).

Conclusion

The change of [18F] HX4 uptake measured on [18F] HX4 PET early during treatment can be considered for implementation in predictive models. With these models patients with a worse prognosis can be selected for treatment intensification.

Correlative analyses between tissue-based hypoxia biomarkers and hypoxia PET imaging in head and neck cancer patients during radiochemotherapy-results from a prospective trial

PURPOSE

Tumor hypoxia impairs the response of head-and-neck cancer (HNSCC) patients to radiotherapy and can be detected both by tissue biomarkers and PET imaging. However, the value of hypoxia biomarkers and imaging for predicting HNSCC patient outcomes are incompletely understood, and potential correlations between tissue and PET data remain to be elucidated. Here, we performed exploratory analyses of potential correlations between tissue-based hypoxia biomarkers and longitudinal hypoxia imaging in a prospective trial of HNSCC patients.

METHODS

Forty-nine patients undergoing chemoradiation for locally advanced HNSCCs were enrolled in this prospective trial. They underwent baseline biopsies and [¹⁸F]FDG PET imaging and [¹⁸F]FMISO PET at weeks 0, 2, and 5 during treatment. Immunohistochemical analyses for p16, Ki67, CD34, HIF1α, CAIX, Ku80, and CD44 were performed, and HPV status was assessed. Biomarker expression was correlated with biological imaging information and patient outcome data.

RESULTS

High HIF1α tumor levels significantly correlated with increased tumor hypoxia at week 2 as assessed by the difference in the [¹⁸F]FMISO tumor-to-background ratios, and high HIF1α and CAIX expressions were both associated with a deferred decrease in hypoxia between weeks 2 and 5. Loco-regional recurrence rates after radiotherapy were significantly higher in patients with high CAIX expression and also increased for high levels of the DNA repair factor Ku80. HPV status did not correlate with any of the tested hypoxia biomarkers, and HPV-positive patients showed higher loco-regional control rates and progression-free survival independent of their hypoxia dynamics.

CONCLUSION

In this exploratory trial, high expression of the tissue-based hypoxia biomarkers HIF1α and CAIX correlated with adverse hypoxia dynamics in HNSCCs during chemoradiation as assessed by PET imaging, and high CAIX levels were associated with increased loco-regional recurrence rates. Hence, hypoxia biomarkers warrant further investigations as potential predictors of hypoxia dynamics and hypoxia-associated radiation resistance.

Prognostic significance of carbonic anhydrase IX overexpression in stage III non-small cell lung cancer patients after neoadjuvant treatment

BACKGROUND

To assess the prognostic importance of carbonic anhydrase IX (CA IX), a hypoxic biomarker, after neoadjuvant treatment in Stage III non-small cell lung cancer (NSCLC) patients.

METHODS

Tissue CA IX expression was examined after surgical resection in 77 patients who had undergone neoadjuvant treatment. The effects of CA IX overexpression and other clinical factors on disease-free survival and overall survival were investigated.

RESULTS

In multivariate analysis, number of neoadjuvant chemotherapy (CT) courses and gender emerged as significant independent predictors for disease-free survival, where administration of 2-3 courses of neoadjuvant chemotherapy (CT) (HR, 3.2 [95% CI 1.3-7.6], p = 0.009) and female gender were associated with poor survival (HR, 3.2 [95% CI 1.3-7.7], p = 0.009). The only significant independent predictor for overall survival was recurrence (HR, 5.6 [95% CI 2.4-12.8], p < 0.001). On the other hand, CA IX overexpression was not associated with disease free survival (p = 0.560) or overall survival (p = 0.799).

DISCUSSION

Our results do not suggest a prognostic role for CA IX overexpression in stage III NSCLC patients who received neoadjuvant treatment.

RNAi-mediated knockdown of CAIX enhances the radiosensitivity of nasopharyngeal carcinoma cell line, CNE-2

Although radiotherapy remains the most powerful as well as the primary treatment modality for nasopharyngeal carcinoma (NPC), approximately 20% of NPC patients still have local recurrence. Carbonic anhydrase IX (CAIX)-related signaling pathways that mediate radioresistance have been found in various kinds of cancer. However, the role of CAIX in NPC radioresistance is still unknown. In this study, we investigated the effect of CAIX silencing on sensitization to ionizing radiation in NPC by using Lipofectamine 2000, which delivers small interfering ribonucleic acid (siRNA) that targets CAIX. Results showed that Lipofectamine 2000 effectively delivered siRNA into the CNE-2 cells, which resulted in the decrease of CAIX expression and cell viability, decrease in cell proliferation and colony formation, and increase in the number of CNE-2 cells stuck in the G₂/M phase of the cell cycle upon induction of ionizing radiation. Increased sensitivity of radiotherapy in CNE-2 cells under hypoxic conditions was correlated with the suppression of CAIX. Cells treated with irradiation in addition to CAIX-siRNA1 demonstrated reduced radiobiological parameters (survival fraction at 2 Gy [SF2]) compared with those treated with irradiation only, with a sensitization-enhancing ratio of 1.47. These findings suggest that CAIX can be a promising therapeutic target for the treatment of radioresistant human NPC.

Prognostic Significance of Carbonic Anhydrase IX Expression in Cancer Patients: A Meta-Analysis

Hypoxia is a characteristic of many solid tumors and an adverse prognostic factor for treatment outcome. Hypoxia increases the expression of carbonic anhydrase IX (CAIX), an enzyme that is predominantly found on tumor cells and is involved in maintaining the cellular pH balance. Many clinical studies investigated the prognostic value of CAIX expression, but most have been inconclusive, partly due to small numbers of patients included. The present meta-analysis was therefore performed utilizing the results of all clinical studies to determine the prognostic value of CAIX expression in solid tumors. Renal cell carcinoma was excluded from this meta-analysis due to an alternative mechanism of upregulation. 958 papers were identified from a literature search performed in PubMed and Embase. These papers were independently evaluated by two reviewers and 147 studies were included in the analysis. The meta-analysis revealed strong significant associations between CAIX expression and all endpoints: overall survival [hazard ratio (HR) = 1.76, 95% confidence interval (95%CI) 1.58–1.98], disease-free survival (HR = 1.87, 95%CI 1.62–2.16), locoregional control (HR = 1.54, 95%CI 1.22–1.93), disease-specific survival (HR = 1.78, 95%CI 1.41–2.25), metastasis-free survival (HR = 1.82, 95%CI 1.33–2.50), and progression-free survival (HR = 1.58, 95%CI 1.27–1.96). Subgroup analyses revealed similar associations in the majority of tumor sites and types. In conclusion, these results show that patients having tumors with high CAIX expression have higher risk of locoregional failure, disease progression, and higher risk to develop metastases, independent of tumor type or site. The results of this meta-analysis further support the development of a clinical test to determine patient prognosis based on CAIX expression and may have important implications for the development of new treatment strategies.

Hypoxia as a Biomarker and for Personalized Radiation Oncology

Tumor hypoxia is a clinically relevant cause of radiation resistance. Direct measurements of tumor oxygenation have been performed predominantly with the Eppendorf histograph and these have defined the reduced prognosis after radiotherapy in poorly oxygenated tumors, especially head-and-neck cancer, cervix cancer and sarcoma. Exogenous markers have been used for immunohistochemical detection of hypoxic tumor areas (pimonidazole) or for positron-emission tomography (PET) imaging (misonidazole). Overexpression of hypoxia-related proteins such as hypoxia-inducible factor-1α (HIF-1α) has also been linked to poor prognosis after radiotherapy and such proteins are considered as potential endogenous hypoxia markers.

Clinical implications of hypoxia biomarker expression in head and neck squamous cell carcinoma: a systematic review

Awareness increases that the tumor biology influences treatment outcome and prognosis in cancer. Tumor hypoxia is thought to decrease sensitivity to radiotherapy and some forms of chemotherapy. Presence of hypoxia may be assessed by investigating expression of endogenous markers of hypoxia (EMH) using immunohistochemistry (IHC). In this systematic review we investigated the effect of EMH expression on local control and survival according to treatment modality in head and neck cancer (head and neck squamous cell carcinoma [HNSCC]). A search was performed in MEDLINE and EMBASE. Studies were eligible for inclusion that described EMH expression in relation to outcome in HNSCC patients. Quality was assessed using the Quality in Prognosis Studies (QUIPS) tool. Hazard ratios for locoregional control and survival were extracted. Forty studies of adequate quality were included. HIF-1a, HIF-2a, CA-IX, GLUT-1, and OPN were identified as the best described EMHs. With exception of HIF-2a, all EMHs were significantly related to adverse outcome in multiple studies, especially in studies where patients underwent single-modality treatment. Positive expression was often correlated with adverse clinical characteristics, including disease stage and differentiation grade. In summary, EMH expression was common in HNSCC patients and negatively influenced their prognosis. Future studies should investigate the effect of hypoxia-modified treatment schedules in patients with high In summary, EMH expression. These may include ARCON, treatment with nimorazole, or novel targeted therapies directed at hypoxic tissue. Also, the feasibility of surgical removal of the hypoxic tumor volume prior to radiotherapy should be investigated.

Histopathological determinants of tumor resistance: a special look to the immunohistochemical expression of carbonic anhydrase IX in human cancers

Intrinsic and acquired drug resistance of tumor cells still causes the failure of treatment regimens in advanced human cancers. It may be driven by intrinsic tumor cells features, or may also arise from micro environmental influences. Hypoxia is a microenvironment feature associated with the aggressiveness and metastasizing ability of human solid cancers. Hypoxic cancer cells overexpress Carbonic Anhydrase IX (CA IX). CA IX ensures a favorable tumor intracellular pH, while contributing to stromal acidosis, which facilitates tumor invasion and metastasis. The overexpression of CA IX is considered an epiphenomenon of the presence of hypoxic, aggressive tumor cells. Recently, a relationship between CA IX overexpression and the cancer stem cells (CSCs) population has been hypothesized. CSCs are strictly regulated by tumor hypoxia and drive a major non-mutational mechanism of cancer drug-resistance. We reviewed the current data concerning the role of CA IX overexpression in human malignancies, extending such information to the expression of the stem cells markers CD44 and nestin in solid cancers, to explore their relationship with the biological behavior of tumors. CA IX is heavily expressed in advanced tumors. A positive trend of correlation between CA IX overexpression, tumor stage/grade and poor outcome emerged. Moreover, stromal CA IX expression was associated with adverse events occurrence, maybe signaling the direct action of CA IX in directing the mesenchymal changes that favor tumor invasion; in addition, membranous/cytoplasmic co-overexpression of CA IX and stem cells markers were found in several aggressive tumors. This suggests that CA IX targeting could indirectly deplete CSCs and counteract resistance of solid cancers in the clinical setting.

The clinical importance of assessing tumor hypoxia: relationship of tumor hypoxia to prognosis and therapeutic opportunities

Tumor hypoxia is a well-established biological phenomenon that affects the curability of solid tumors, regardless of treatment modality. Especially for head and neck cancer patients, tumor hypoxia is linked to poor patient outcomes. Given the biological problems associated with tumor hypoxia, the goal for clinicians has been to identify moderately to severely hypoxic tumors for differential treatment strategies. The "gold standard" for detecting and characterizing of tumor hypoxia are the invasive polarographic electrodes. Several less invasive hypoxia assessment techniques have also shown promise for hypoxia assessment. The widespread incorporation of hypoxia information in clinical tumor assessment is severely impeded by several factors, including regulatory hurdles and unclear correlation with potential treatment decisions. There is now an acute need for approved diagnostic technologies for determining the hypoxia status of cancer lesions, as it would enable clinical development of personalized, hypoxia-based therapies, which will ultimately improve outcomes. A number of different techniques for assessing tumor hypoxia have evolved to replace polarographic pO2 measurements for assessing tumor hypoxia. Several of these modalities, either individually or in combination with other imaging techniques, provide functional and physiological information of tumor hypoxia that can significantly improve the course of treatment. The assessment of tumor hypoxia will be valuable to radiation oncologists, surgeons, and biotechnology and pharmaceutical companies who are engaged in developing hypoxia-based therapies or treatment strategies.

Prognostic value of hypoxia-associated markers in advanced larynx and hypopharynx squamous cell carcinoma

OBJECTIVES/HYPOTHESIS

To determine the prognostic value of hypoxia-associated markers carbonic anhydrase-9 (CA-9) and hypoxia-inducible factor-1α (HIF-1α) in advanced larynx and hypopharynx squamous cell carcinoma (SCCa) treated by organ preservation strategies.

STUDY DESIGN

Retrospective cohort study.

METHODS

Pretreatment CA-9 and HIF-1α expression, clinicopathologic data, and tumor volume were analyzed in a series of 114 patients with T3-4 SCCa larynx or hypopharynx treated by (chemo)radiation.

RESULTS

Adverse prognostic factors for locoregional control were T4 classification (P = 0.008), and for disease-specific survival were CA-9 positivity (P = 0.039), T4 classification (P = 0.001), larger tumor volume (P = 0.004), N1-3 classification (P = 0.002), and pretreatment hemoglobin < 13.0 g/dl (P = 0.014). With increasing CA-9 expression, there was a trend to increasing tumor recurrence (P trend = 0.009) and decreasing survival (P trend = 0.002). On multivariate analysis, independent variables were T4 classification (hazard ratio [HR] 13.54, P = 0.01) for locoregional failure, and CA-9 positivity (HR = 8.02, P = 0.042) and higher tumor volume (HR = 3.33, P = 0.007) for disease-specific mortality.

CONCLUSION

This is the first study to look specifically at T3 and T4 SCCa larynx and hypopharynx for a relationship between hypoxia-associated marker expression and clinical outcome. Pretreatment immunohistochemical CA-9 expression is an adverse prognostic factor for disease-specific survival, indicating that CA-9 expression may confer a more aggressive tumor phenotype.

HIF-1α and CA-IX as predictors of locoregional control for determining the optimal treatment modality for early-stage laryngeal carcinoma

BACKGROUND

The purpose of this study was to examine the predictive value of hypoxia-inducible factor (HIF)-1α, carbonic anhydrase (CA)-IX, glucose transporter (GLUT)-1, cyclooxygenase (COX)-2, Ki-67, and erythropoietin receptor (EPOR) as immunohistochemical markers for determining the optimal treatment modality for early stage laryngeal carcinoma.

METHODS

Tissue samples from 42 early stage laryngeal carcinomas treated with radiotherapy alone were analyzed immunohistochemically for the expression of 6 markers. The Kaplan-Meier method, univariate and multivariate analyses, and the Cox proportional hazards model were used to analyze the associations between patient and tumor characteristics and immunohistochemical results, and locoregional control.

RESULTS

Increased expression of HIF-1α and CA-IX was significantly correlated with residual tumor; no correlations were observed for the other immunohistochemical markers.

CONCLUSION

High levels of HIF-1α or CA-IX expression were significantly correlated with residual tumor after radiotherapy for early stage laryngeal carcinomas. Alternative treatment modalities to primary radiotherapy should be considered for early stage laryngeal carcinomas showing high HIF-1α or CA-IX expression.

Carbonic anhydrase IX as an imaging and therapeutic target for tumors and metastases

Carbonic anhydrase IX (CAIX) which is a zinc containing metalloprotein, efficiently catalyzes the reversible hydration of carbon dioxide. It is constitutively up-regulated in several cancer types and has an important role in tumor progression, acidification and metastasis. High expression of CAIX generally correlates with poor prognosis and is related to a decrease in the disease-free interval following successful therapy. Therefore, it is considered as a prognostic indicator in oncology.In this review, we describe CAIX regulation and its role in tumor hypoxia, acidification and metastasis. In addition, the molecular imaging of CAIX and its potential for use in cancer detection, diagnosis, staging, and for use in following therapy response is discussed. Both antibodies and small molecular weight compounds have been used for targeted imaging of CAIX expression. The use of CAIX expression as an attractive and promising candidate marker for systemic anticancer therapy is also discussed.

The gene expression profile of inflammatory, hypoxic and metabolic genes predicts the metastatic spread of human head and neck squamous cell carcinoma

OBJECTIVES

To assess the prognostic value of the expression profile of the main genes implicated in hypoxia, glucose and lactate metabolism, inflammation, angiogenesis and extracellular matrix interactions for the metastatic spread of head and neck squamous cell carcinoma.

PATIENTS AND METHODS

Using a high-throughput qRT-PCR, we performed an unsupervised clustering analysis based on the expression of 42 genes for 61 patients. Usual prognostic factors and clustering analysis results were related to metastasis free survival.

RESULTS

With a median follow-up of 48months, 19 patients died from a metastatic evolution of their head and neck squamous cell carcinoma and one from a local recurrence. The unsupervised clustering analysis distinguished two groups of genes that were related to metastatic evolution. A capsular rupture (p=0.005) and the "cluster CXCL12 low" (p=0.002) were found to be independent prognostic factors for metastasis free survival. Using a Linear Predictive Score methodology, we established a 9-gene model (VHL, PTGER4, HK1, SLC16A4, DLL4, CXCL12, CXCR4, PTGER3 and CA9) that was capable of classifying the samples into the 2 clusters with 90% accuracy.

CONCLUSION

In this cohort, our clustering analysis underlined the independent prognostic value of the expression of a panel of genes involved in hypoxia and tumor environment. It allowed us to define a 9-gene model which can be applied routinely to classify newly diagnosed head and neck squamous cell carcinoma. If confirmed by an independent prospective study, this approach may help future clinical management of these aggressive tumors.

Cancer stem cell radioresistance and enrichment: where frontline radiation therapy may fail in lung and esophageal cancers

Many studies have highlighted the role cancer stem cells (CSC) play in the development and progression of various types of cancer including lung and esophageal cancer. More recently, it has been proposed that the presence of CSCs affects treatment efficacy and patient prognosis. In reviewing this new area of cancer biology, we will give an overview of the current literature regarding lung and esophageal CSCs and radioresistance of CSC, and discuss the potential therapeutic applications of these findings.

A 26-gene hypoxia signature predicts benefit from hypoxia-modifying therapy in laryngeal cancer but not bladder cancer

PURPOSE

Tumor hypoxia is associated with a poor prognosis, hypoxia modification improves outcome, and hypoxic status predicts benefit from treatment. Yet, there is no universal measure of clinical hypoxia. The aim of this study was to investigate whether a 26-gene hypoxia signature predicted benefit from hypoxia-modifying treatment in both cancer types.

EXPERIMENTAL DESIGN

Samples were available from 157 T2-T4 laryngeal cancer and 185 T1-T4a bladder cancer patients enrolled on the accelerated radiotherapy with carbogen and nicotinamide (ARCON) and bladder carbogen nicotinamide (BCON) phase III randomized trials of radiotherapy alone or with carbogen and nicotinamide (CON) respectively. Customized TaqMan low density arrays (TLDA) were used to assess expression of the 26-gene signature using quantitative real-time PCR. The median expression of the 26 genes was used to derive a hypoxia score (HS). Patients were categorized as TLDA-HS low (≤median) or TLDA-HS high (>median). The primary outcome measures were regional control (RC; ARCON) and overall survival (BCON).

RESULTS

Laryngeal tumors categorized as TLDA-HS high showed greater benefit from ARCON than TLDA-HS low tumors. Five-year RC was 81% (radiotherapy alone) versus 100% (CON) for TLDA-HS high (P=0.009). For TLDA-HS low, 5-year RC was 91% (radiotherapy alone) versus 90% (CON; P=0.90). TLDA-HS did not predict benefit from CON in bladder cancer.

CONCLUSION

The 26-gene hypoxia signature predicts benefit from hypoxia-modifying treatment in laryngeal cancer. These findings will be evaluated in a prospective clinical trial.

Pattern of CAIX expression is prognostic for outcome and predicts response to ARCON in patients with laryngeal cancer treated in a phase III randomized trial

BACKGROUND AND PURPOSE

In a phase III trial in patients with advanced stage laryngeal carcinoma comparing ARCON (accelerated radiotherapy with carbogen breathing and nicotinamide) to accelerated radiotherapy alone (AR) the prognostic and predictive value of CAIX, a hypoxia-associated protein, was investigated.

MATERIAL AND METHODS

261 Paraffin embedded tumor biopsies and 79 fresh frozen biopsies from patients entered in the trial were immunohistochemically stained for CAIX. CAIX-fraction and CAIX expression pattern were related to tumor control and patient survival.

RESULTS

Low CAIX-fraction was prognostic for worse regional control and overall survival in patients treated with AR. Patients with a low CAIX-fraction treated with ARCON had better regional control and metastasis-free survival compared to AR (RC 97% vs 71%, p < 0.01 and MFS 92% vs 69%, p = 0.06). Patients with a perinecrotic CAIX staining pattern had a significantly worse local control, metastasis-free and overall survival compared to patients with a diffuse pattern (65% vs 84%, p = 0.01, 70% vs 96%, p < 0.01 and 42% vs 71%, p < 0.01 respectively), and this could not be improved with ARCON. After multivariate analysis CAIX pattern and N-stage emerged as significant predictors for metastasis-free survival and overall survival.

CONCLUSIONS

ARCON improves regional control and metastasis-free survival only in patients with low CAIX expression. The different patterns of CAIX expression suggest different mechanisms of upregulation and have important prognostic value.

An immunohistochemical study of the expression of the hypoxia markers Glut-1 and Ca-IX in canine sarcomas

Tumor hypoxia has been associated with increased malignancy, likelihood of metastasis, and increased resistance to radiotherapy and chemotherapy in human medicine. Hypoxia-inducible factor-1 (HIF-1) is a key transcription factor that is induced by tumor hypoxia and regulates the pathways involved in cellular response and adaptation to the hostile tumor microenvironment. HIF-1 induces transcription of different proteins, including Ca-IX and Glut-1, which are considered endogenous markers of chronic hypoxia in solid tumors in humans. In this study, sections from 40 canine sarcomas (20 histiocytic sarcomas and 20 low-grade soft-tissue sarcomas) were immunostained for these markers. Expression of Glut-1 was scored based on percentage of positive staining cells (0 = <1%; 1 = 1%-50%; 2 = >50%) and intensity of cellular staining (1 = weak; 2 = strong); Ca-IX was scored based on percentage of positive cells (0 = <1%; 1 = 1%-30%; 2 = >30%). Intratumoral microvessel density was measured using CD31 to assess intratumoral neoangiogenesis. Histiocytic sarcomas showed statistically significant higher Glut-1 immunoreactivity and angiogenesis than did low-grade soft-tissue sarcomas. Intratumoral microvessel density in histiocytic sarcomas was positively associated with Glut-1 immunoreactivity score. These findings suggest a potential role of hypoxia in the biology of these tumors and may provide a base for investigation of the potential prognostic use of these markers in naturally occurring canine tumors.

Prospective technical validation and assessment of intra-tumour heterogeneity of a low density array hypoxia gene profile in head and neck squamous cell carcinoma

BACKGROUND AND PURPOSE

Tumour hypoxia is associated with a poor prognosis in head and neck squamous cell carcinoma (HNSCC), however there is no accepted method for assessing hypoxia clinically. We aimed to conduct a technical validation of a hypoxia gene expression signature using the TaqMan Low Density Array (TLDA) platform to investigate if this approach reliably identified hypoxic tumours.

MATERIALS AND METHODS

Tumour samples (n=201) from 80 HNSCC patients were collected prospectively from two centres. Fifty-three patients received pimonidazole prior to surgery. TaqMan Low Density Array-Hypoxia Scores (TLDA-HS) were obtained by quantitative real-time PCR (qPCR) using a 25-gene signature and customised TLDA cards. Assay performance was assessed as coefficient of variation (CoV).

RESULTS

The assay was sensitive with linear reaction efficiencies across a 4 log(10) range of inputted cDNA (0.001-10 ng/μl). Intra- (CoV=6.9%) and inter- (CoV=2.0%) assay reproducibility were excellent. Intra-tumour heterogeneity was lower for TLDA-HS (23.2%) than for pimonidazole (67.2%) or single gene measurements of CA9 (62.2%), VEGFA (45.0%) or HIG2 (39.4%). TLDA-HS in HNSCC cell lines increased with decreasing pO(2). TLDA-HS correlated with Affymetrix U133 Plus 2.0 microarray HS (p<0.01) and positive pimonidazole scores (p=0.005).

CONCLUSIONS

Gene expression measurements of hypoxia using a 25-gene signature and TLDA cards are sensitive, reproducible and associated with lower intra-tumour heterogeneity than assaying individual genes or pimonidazole binding. The approach is suitable for further assessment of prognostic and predictive capability in clinical trial material.

Lack of prognostic effect of carbonic anhydrase-9, hypoxia inducible factor-1α and bcl-2 in 286 patients with early squamous cell carcinoma of the glottic larynx treated with radiotherapy

AIMS

To evaluate the prognostic significance of potential tumour markers of hypoxia and apoptosis in early squamous cell carcinoma of the glottic larynx managed with radiotherapy.

MATERIALS AND METHODS

In total, 382 patients with T1 and T2 squamous cell carcinoma of the glottic larynx (vocal cords) received radical radiotherapy (50-55 Gy, in 16 fractions in 98% of cases). Pre-treatment haemoglobin was available for 328 patients; biopsy samples were available for 286. Immunohistochemistry was carried out for carbonic anhydrase-9 (CA-9), hypoxia inducible factor-1α (HIF-1α) and Bcl-2.

RESULTS

At 5 years, locoregional control was achieved in 88.2%, cancer-specific survival in 95.0% and overall survival in 78.7%. Adverse prognostic factors for locoregional tumour recurrence were pre-treatment haemoglobin <13.0 g/dl (P = 0.035, Log rank test; sensitivity 0.28, specificity 0.84) and stage T2 rather than T1 (P = 0.002). The effect of haemoglobin level on locoregional control was not significant when stratified by the median of 14.2 g/dl (P = 0.43) or as a continuous variable (P = 0.59). High CA-9 (P = 0.11), HIF-1α (P = 0.67) and Bcl-2 (P = 0.77) expression had no prognostic significance.

CONCLUSIONS

High CA-9, HIF-1α and Bcl-2 do not add to the prognostic significance of tumour stage and lower haemoglobin in predicting failure of local control in early glottic larynx squamous cell carcinoma managed with radiotherapy. The effect of haemoglobin was not strong enough to be useful as a prognostic biomarker.

Predicting recurrence after radiotherapy in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Radiotherapy is a mainstay of treatment, either alone for early stage tumors or combined with chemotherapy for late stage tumors. An overall 5-year survival rate of around 50% for HNSCC demonstrates that treatment is often unsuccessful. Prediction of outcome is, therefore, aimed at sparing patients from ineffective and toxic treatments on the one hand, and indicating more successful treatment modalities on the other. Both functional and genetic assays have been developed to predict intrinsic radiosensitivity, hypoxia, and repopulation rate. Few, however, have shown consistent correlations with outcome across multiple studies. Messenger RNA and microRNA profiling show promise for predicting hypoxia, whereas epidermal growth factor receptor expression combined with other measures of tumor differentiation grade shows promise for predicting repopulation rate. Intrinsic radiosensitivity assays have not proven useful to date, although development of repair protein foci assays indicates promise from preclinical studies. Assays for cancer stem cell content have shown promise in several clinical studies. In addition, 2 assays showing robustness as predictors for outcome in HNSCC are human papilloma virus status and epidermal growth factor receptor expression. Neither these nor stem cell assays, however, can as yet reliably indicate alternative and better treatments for poor prognosis patients. It would be of great value to have assays that predict the benefit for an individual from combining new molecularly targeted agents with radiotherapy to increase response, in particular those that exploit tumor mutations to provide tumor specificity. Predictive assays are being developed for detecting defects in repair pathways for single- and double-strand DNA breaks, which should allow selection of drugs targeting the appropriate backup pathway, thus exploiting the concept of synthetic lethality. This is one of the most promising areas for prediction, both currently and in the future.

Carbonic anhydrase-9 expression in head and neck cancer: a meta-analysis

The purpose of the study was to compare CA-9 positivity versus CA-9 negativity in head and neck malignancies and to correlate levels of CA-9 with tumor grade, size, and nodal status. Overall and disease-free survival were also compared for CA-9 positive and negative tumors. A literature search was performed using Medline, Embase, Ovid and Cochrane databases for studies between 1990 and 2009. Carbonic anhydrase IX, CA IX, CA-9, head and neck, and survival were used as search terms. Random-effect meta-analytical techniques were conducted for outcome measures of overall survival and disease-free survival. Sixteen studies matched the selection criteria, reporting on 1,470 patients. Eight hundred and forty two specimens were reported as being CA-9 positive or negative: 512 (60.81%) were CA-9 positive and 330 (39.19%) were CA-9 negative. Nine hundred and eighty specimens had levels of CA-9 expression recorded: 547 (55.82%) had high levels of CA-9 and 433 (44.18%) had low CA-9 levels. Survival was significantly reduced if the tumor was positive for CA-9 (P < 0.0001). Disease-free survival is significantly reduced in patients with CA-9 positive (P = 0.0008) head and neck malignant tumors. The presence of CA-9 in head and neck malignant tumors is associated with reduced overall survival and disease-free survival.

Radiation resistance of cancer stem cells: the 4 R's of radiobiology revisited

There is compelling evidence that many solid cancers are organized hierarchically and contain a small population of cancer stem cells (CSCs). It seems reasonable to suggest that a cancer cure can be achieved only if this population is eliminated. Unfortunately, there is growing evidence that CSCs are inherently resistant to radiation, and perhaps other cancer therapies. In general, success or failure of standard clinical radiation treatment is determined by the 4 R's of radiobiology: repair of DNA damage, redistribution of cells in the cell cycle, repopulation, and reoxygenation of hypoxic tumor areas. We relate recent findings on CSCs to these four phenomena and discuss possible consequences.

Prognostic relevance of carbonic anhydrase-IX in high-risk, early-stage cervical cancer: a Gynecologic Oncology Group study

OBJECTIVES

This study aimed to determine whether carbonic anhydrase-IX (CA-IX) was associated with progression-free survival (PFS) and overall survival (OS) in women with high-risk, early-stage cervical cancer treated with adjuvant pelvic radiotherapy with or without radiosensitizing chemotherapy.

METHODS

CA-IX expression was detected using an immunohistochemistry assay and categorized as low when <or=80% of tumor cells exhibited CA-IX staining and high when >80% tumor cells display CA-IX staining. Associations between CA-IX expression and clinical characteristics, angiogenesis marker expression, and clinical outcome were evaluated.

RESULTS

High CA-IX expression was observed in 35/166 (21.1%) of cases. CA-IX expression was not associated with age, race, stage, cell type, grade, positive margins, parametrial extensions, positive lymph nodes, or lymphovascular space invasion but was associated with tumor size categorized as <2 , 2-2.9 , or >or=3 cm (high expression: 4.7% vs. 23.2% vs. 32.5%, P=0.003) and cervical invasion confined to the inner two-thirds compared with the outer third of the cervix (high expression: 6.1% vs. 23.7%, P=0.028). CA-IX expression was not associated with immunohistochemical expression of p53, CD31, CD105, thrombospondin-1, or vascular endothelial growth factor-A. Women with high versus low CA-IX expression had similar PFS (P=0.053) and significantly worse OS (P=0.044). After adjusting for prognostic clinical covariates, high CA-IX expression was an independent prognostic factor for PFS (hazard ratio [HR]=2.12; 95% confidence interval [CI]=1.13-3.95; P=0.019) and OS (HR=2.41; 95% CI=1.24-4.68; P=0.009).

CONCLUSIONS

Tumor hypoxia measured by immunohistochemical expression of CA-IX is an independent prognostic factor for both PFS and OS in high-risk, early-stage cervical cancer.

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.

Co-expression of Hif1alpha and CAIX is associated with poor prognosis in oral squamous cell carcinoma patients

BACKGROUND

This study investigates the prognostic impact of the expression of hypoxia-inducible factor 1alpha (Hif1alpha) and carbonic anhydrase IX (CAIX) detected by immunohistochemistry in oral squamous cell carcinoma (OSCC).

METHODS

Statistical analysis of immunohistochemical results with clinical parameters including survival outcomes was performed for 80 OSCC patients.

RESULTS

Patients with a low expression of both proteins survived on average 54.8 months, whereas those with an increased expression of Hif1alpha in their tumors combined with a low expression of CAIX survived on average only 37.6 months (P = 0.026). In multivariate Cox's regression hazard analysis, again patients with a low expression of Hif1alpha/CAIX had the best prognosis, whereas patients with increased Hif1alpha and low CAIX expression carried a 4.97-fold increased risk of tumor-related death (P = 0.042).

CONCLUSION

A co-detection of low Hif1alpha/CAIX expression is significantly correlated with a better prognosis for OSCC patients, which may have implications for therapy options for these patients.

Can hypoxia-PET map hypoxic cell density heterogeneity accurately in an animal tumor model at a clinically obtainable image contrast?

BACKGROUND

PET allows non-invasive mapping of tumor hypoxia, but the combination of low resolution, slow tracer adduct-formation and slow clearance of unbound tracer remains problematic. Using a murine tumor with a hypoxic fraction within the clinical range and a tracer post-injection sampling time that results in clinically obtainable tumor-to-reference tissue activity ratios, we have analyzed to what extent inherent limitations actually compromise the validity of PET-generated hypoxia maps.

MATERIALS AND METHODS

Mice bearing SCCVII tumors were injected with the PET hypoxia-marker fluoroazomycin arabinoside (FAZA), and the immunologically detectable hypoxia marker, pimonidazole. Tumors and reference tissue (muscle, blood) were harvested 0.5, 2 and 4h after FAZA administration. Tumors were analyzed for global (well counter) and regional (autoradiography) tracer distribution and compared to pimonidazole as visualized using immunofluorescence microscopy.

RESULTS

Hypoxic fraction as measured by pimonidazole staining ranged from 0.09 to 0.32. FAZA tumor to reference tissue ratios were close to unity 0.5h post-injection but reached values of 2 and 6 when tracer distribution time was prolonged to 2 and 4h, respectively. A fine-scale pixel-by-pixel comparison of autoradiograms and immunofluorescence images revealed a clear spatial link between FAZA and pimonidazole-adduct signal intensities at 2h and later. Furthermore, when using a pixel size that mimics the resolution in PET, an excellent correlation between pixel FAZA mean intensity and density of hypoxic cells was observed already at 2h post-injection.

CONCLUSIONS

Despite inherent weaknesses, PET-hypoxia imaging is able to generate quantitative tumor maps that accurately reflect the underlying microscopic reality (i.e., hypoxic cell density) in an animal model with a clinical realistic image contrast.

Hypoxia in larynx carcinomas assessed by pimonidazole binding and the value of CA-IX and vascularity as surrogate markers of hypoxia

Tumour hypoxia as driving force in tumour progression and treatment resistance has been well established. Assessment of oxygenation status of tumours may provide important prognostic information and improve selection of patients for treatment. In this study, a large homogenous group of 103 laryngeal carcinomas has been investigated in the presence of hypoxia by pimonidazole binding and the usefulness of Carbonic anhydrase IX (CA-IX) and vascular parameters as surrogate markers of hypoxia. These parameters are further related to clinical and biological characteristics. One hundred and three patients with T2-T4 larynx carcinoma were included. They were given the hypoxia marker pimonidazole intravenously (i.v.) 2h prior to taking a biopsy. Expression of all the parameters was examined by immunohistochemistry, excluding large necrotic areas. Among tumours a large variation in pimonidazole positivity (hypoxic fraction based on pimonidazole, HFpimo) (range 0-19%) and CA-IX expression (hypoxic fraction based on CA-IX staining, HFCA-IX) (range 0-34%) was observed. In 67% of the tumours, hypoxia involved 1% of the viable tumour area. HFpimo and HFCA-IX correlated significantly albeit weak (p=0.04). Both parameters showed weak inverse correlations with the relative vascular area (RVA) (p=0.01). HFpimo was further associated with histopathological grade, with poorly differentiated tumours being more hypoxic. The fraction of the tumour area positive for both pimonidazole and CA-IX correlated significantly with N stage. From these results, it was concluded that CA-IX and RVA have only limited value for measuring hypoxia and are not as robust as pimonidazole, probably due to the influence of other factors in the microenvironment. A combination of staining patterns of exogenous and endogenous markers might give important additive information about tumour biology and behaviour.

Effect of HPV-associated p16INK4A expression on response to radiotherapy and survival in squamous cell carcinoma of the head and neck

PURPOSE

A subset of head and neck cancers is associated with the human papillomavirus (HPV). Viral infection is closely correlated with expression of p16(INK4A) in these tumors. We evaluated p16(INK4A) as a prognostic marker of treatment response and survival in a well-defined and prospectively collected cohort of patients treated solely with conventional radiotherapy in the Danish Head and Neck Cancer Group (DAHANCA) 5 trial.

PATIENTS AND METHODS

Immunohistochemical expression of p16(INK4A) was analyzed in pretreatment paraffin-embedded tumor blocks from 156 patients treated with conventional primary radiotherapy alone. The influence of p16(INK4A) status on locoregional tumor control, disease-specific survival, and overall survival after radiotherapy was evaluated.

RESULTS

p16(INK4A) positivity was found in 35 tumors (22%). Tumor-positivity for p16(INK4A) was significantly correlated with improved locoregional tumor control (5-year actuarial values 58% v 28%; P = .0005), improved disease-specific survival (72% v 34%; P = .0006), and improved overall survival (62% v 26%; P = .0003). In multivariate analysis, p16(INK4A) remained a strong independent prognostic factor for locoregional failure (hazard ratio [HR], 0.35; 95% CI, 0.19 to 0.64), disease-specific death (HR, 0.36; 95% CI, 0.20 to 0.64), and overall death (HR, 0.44; 95% CI, 0.28 to 0.68).

CONCLUSION

Expression of p16(INK4A) has a major impact on treatment response and survival in patients with head and neck cancer treated with conventional radiotherapy.

Exploring the role of cancer stem cells in radioresistance

Radiobiological research over the past decades has provided evidence that cancer stem cell content and the intrinsic radiosensitivity of cancer stem cells varies between tumours, thereby affecting their radiocurability. Translation of this knowledge into predictive tests for the clinic has so far been hampered by the lack of methods to discriminate between stem cells and non-stem cells. New technologies allow isolation of cells expressing specific surface markers that are differentially expressed in tumour cell subpopulations that are enriched for cancer stem cells. Combining these techniques with functional radiobiological assays holds the potential to elucidate the role of cancer stem cells in radioresistance in individual tumours, and to use this knowledge for the development of predictive markers for optimization of radiotherapy.

Carbonic anhydrase IX and response to postmastectomy radiotherapy in high-risk breast cancer: a subgroup analysis of the DBCG82 b and c trials

INTRODUCTION

A significant survival improvement after postmastectomy radiotherapy was identified in the Danish Breast Cancer Cooperative Group (DBCG82) b and c studies and in the British Columbia Randomized Radiation Trial. Recently, potential predictive value regarding response to postmastectomy radiotherapy was reported for carbonic anhydrase (CA) IX in a study (reported in abstract form) that included 160 patients. The purpose of the present study was to examine the importance of CA IX to response to postmastectomy radiotherapy in the larger scaled DBCG82 b and c studies.

METHODS

The DBCG82 b and c studies included 3,083 high-risk Danish breast cancer patients. The women were randomly assigned to postmastectomy radiotherapy plus systemic therapy (cyclophosfamide, methotrexate and fluorouracil in premenopausal women; and tamoxifen in postmenopausal women) or to systemic therapy alone. Cores from invasive tumour-containing paraffin blocks from 1,000 patients (more than seven nodes surgically removed) were transferred to tissue microarrays. Tissue microarray sections were stained immunohistochemically for CA IX (M75). The median follow up for patients remaining alive was 17 years. Clinical end-points were loco-regional recurrence, distant metastases, disease-specific survival and overall survival. Statistical analyses included kappa statistics, chi2 or exact tests, Kaplan-Meier probability plots, Log-rank test and Cox regression analyses.

RESULTS

CA IX was assessable in 945 cores. The percentage of tumours positive for CA IX was 16% (> or = 10% invasive tumour staining). CA IX was not an independent prognostic marker for survival, distant metastases, or locoregional recurrence in the subgroup of 945 patients or within either of the two randomization arms. In subgroup analyses, however, CA IX was an independent prognostic marker for overall survival among postmenopausal women (P = 0.001), women with one to three positive nodes (P = 0.02) and hormone receptor positive women (P = 0.001). Fifteen-year probabilities of overall survival were improved by 9% and 7% after postmastectomy radiotherapy for the subgroups of CA IX negative and CA IX positive patients, respectively.

CONCLUSION

Within this series of 945 high-risk premenopausal and postmenopausal women, positivity for CA IX was not overall an independent prognostic marker for survival; only in subgroup analyses was it found to have prognostic value. The improvement in 15-year survival after postmastectomy radiotherapy was of similar magnitude in the two subgroups of CA IX positive and CA IX negative patients.

Hypoxic radiosensitization: adored and ignored

Since observations from the beginning of the last century, it has become well established that solid tumors may contain oxygen-deficient hypoxic areas and that cells in such areas may cause tumors to become radioresistant. Identifying hypoxic cells in human tumors has improved by the help of new imaging and physiologic techniques, and a substantial amount of data indicates the presence of hypoxia in many types of human tumors, although with a considerable heterogeneity among individual tumors. Controlled clinical trials during the last 40 years have indicated that this source of radiation resistance can be eliminated or modified by normobaric or hyperbaric oxygen or by the use of nitroimidazoles as hypoxic radiation sensitizers. More recently, attention has been given to hypoxic cytotoxins, a group of drugs that selectively or preferably destroys cells in a hypoxic environment. An updated systematic review identified 10,108 patients in 86 randomized trials designed to modify tumor hypoxia in patients treated with curative attempted primary radiation therapy alone. Overall modification of tumor hypoxia significantly improved the effect of radiotherapy, with an odds ratio of 0.77 (95% CI, 0.71 to 0.86) for the outcome of locoregional control and with an associated significant overall survival benefit (odds ratio = 0.87; 95% CI, 0.80 to 0.95). No significant influence was found on the incidence of distant metastases or on the risk of radiation-related complications. Ample data exist to support a high level of evidence for the benefit of hypoxic modification. However, hypoxic modification still has no impact on general clinical practice.

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.