Textural features of hypoxia PET predict survival in head and neck cancer during chemoradiotherapy.

PURPOSE: The aim of this study was to investigate whether textural features of tumour hypoxia, assessed with serial [18F]fluoromisonidazole (FMISO)-PET, were able to predict clinical outcome in patients with head and neck squamous cell carcinoma (HNSCC, T1-4, N+, M0) during chemoradiotherapy (CRT). METHODS: In a preliminary evaluation of a prospective trial, tumour hypoxia was evaluated in 29 patients via serial FMISO-PET before and during CRT. All patients received an initial [18F]fluorodeoxyglucose (FDG)-PET before CRT, and tumour regions were defined on this FDG-PET. The first-order metrics tumour-to-background ratio (TBRmean, TBRmax, TBRpeak), coefficient of variation, total lesion uptake and integral non-uniformity were calculated for all scans. Further, 3 second-order (textural) features from two grey-level matrices were calculated, as well as differential non-uniformity (udiff). Prognostic value was examined by median split for group separation (GS) in Kaplan-Meier estimates and correlated with overall survival (OS), quantified via log-rank tests (p ≤ 0.05) and group-relative hazard ratios (HR). RESULTS: Within a median follow-up of 29.6 months (95% CI: 16.8-48.0 months), no first-order metrics predicted OS with a significant GS (all p > 0.05) on any FMISO-PET scan. Only udiff before and in week 2 during CRT (p = 0.03, HR = 10.8 and p = 0.05, HR = 5.2) and non-uniformity from grey-level run length matrix in week 2 separated prognostic groups (p = 0.05, HR = 5.3); lower values were correlated with better OS. Further, the decrease in udiff from before CRT to week 2 was correlated with better OS (p = 0.04, HR = 9.4). FDG-PET before CRT did not predict outcome in any measure. CONCLUSIONS: Textural features on FMISO-PET scans before CRT, in week 2 and, to a limited degree, the change of features during CRT, were able to identify head and neck squamous cell carcinoma patients with better OS, suggesting that a higher homogeneity of the degree of hypoxia in tumours could correlate with a better outcome after CRT.

'Oxygen Level in a Tissue' - What Do Available Measurements Really Report?

The aim of the paper is to discuss what currently is feasible clinically to measure the level of oxygen and how that measurement can be clinically useful. Because oxygen in tissues is quite heterogeneous and all methods of measurement can only provide an average across heterogeneities at some spatial and temporal resolution, the values that are obtained may have limitations on their clinical utility. However, even if such limitations are significant, if one utilizes repeated measurements and focuses on changes in the measured levels, rather than 'absolute levels', it may be possible to obtain very useful clinical information. While these considerations are especially pertinent in cancer, they also pertain to most other types of pathology.

Clinical and Statistical Considerations when Assessing Oxygen Levels in Tumors: Illustrative Results from Clinical EPR Oximetry Studies.

The success of treatment for malignancies, especially those undergoing radiation therapy or chemotherapy, has long been recognized to depend on the degree of hypoxia in the tumor. In addition to the prognostic value of knowing the tumor's initial level of hypoxia, assessing the tumor oxygenation during standard therapy or oxygen-related treatments (such as breathing oxygen-enriched gas mixtures or taking drugs that can increase oxygen supply to tissues) can provide valuable data to improve the efficacy of treatments. A series of early clinical studies of tumors in humans are ongoing at Dartmouth and Emory using electron paramagnetic resonance (EPR) oximetry to assess tumor oxygenation, initially and over time during either natural disease progression or treatment. This approach has the potential for reaching the long-sought goal of enhancing the effectiveness of cancer therapy. In order to effectively reach this goal, we consider the validity of the practical and statistical assumptions when interpreting the measurements made in vivo for patients undergoing treatment for cancer.

Lacking hypoxia-mediated downregulation of E-cadherin in cancers of the uterine cervix.

BACKGROUND: Experimental studies have established a causal connection between tumour hypoxia, hypoxia-associated proteome changes and downregulation of E-cadherin, the final common pathway of epithelial-to-mesenchymal transition (EMT). Our study aimed at elucidating the interrelationship of these processes in cancers of the uterine cervix in vivo. METHODS: Tumour oxygenation was assessed in 48 squamous cell carcinomas (SCC) of the uterine cervix using polarographic needle electrodes. The expression pattern of E-cadherin was investigated by immunohistochemistry and western blotting, and was compared with that of the hypoxia-inducible proteins glucose transporter (GLUT)-1 and carbonic anhydrase (CA) IX in biopsy specimens of the oxygenation measurement tracks. RESULTS: The majority of cervical cancers (52%) were E-cadherin positive, with a complete absence of the antigen in only 10% of the tumours. No correlation was found between the level of E-cadherin expression and the oxygenation status (mean pO(2), median pO(2) and hypoxic fractions). In patients showing partial expression of E-cadherin (38%), staining was not preferentially diminished in GLUT-1- or CA IX-positive areas, and loss of E-cadherin occurred independently of tumour cell scattering. CONCLUSION: Our data provide no evidence in favour of a hypoxia-induced EMT as a mechanistic basis of cervical cancer invasiveness.

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.

Intra- and intertumor heterogeneities in total, chronic, and acute hypoxia in xenografted squamous cell carcinomas. Detection and quantification using (immuno-)fluorescence techniques.

BACKGROUND: Heterogeneously distributed hypoxia is a major characteristic of solid tumors. (Immuno-)fluorescence detection of hypoxia in experimental tumors is frequently assessed in a single central section; however, this may not necessarily be representative of the whole tumor. In order to determine whether analysis of one central section is exemplary of the whole tumor and whether different volumes have an impact on tumor oxygenation, we assessed the fractions of total (TH), chronic (CH), and acute hypoxia (AH) throughout different layers of tumors of varying volumes. MATERIALS AND METHODS: Xenografted FaDu human squamous cell carcinomas of different volumes were investigated for intra- and intertumor heterogeneities. Tissue blocks located at the apical, central, and basal layer were sliced from individual tumors. Four serial cryosections were analyzed from each tissue block. Vital tumor tissue was explored for the distribution of Hoechst 33342 (perfusion), pimonidazole (hypoxia), and CD31 (endothelium) to assess TH, CH, and AH. RESULTS: Fractions of TH, CH, and AH were consistently similar in the serial sections of individual tissue blocks. However, significant differences were found between the apical, central, and basal blocks that were even opposite depending on the tumor volume. Pooled data from all three tissue blocks revealed significantly higher fractions of hypoxia in the large tumors than in the small tumors. CONCLUSION: FaDu tumors exhibit a heterogeneous and volume-dependent oxygenation status. Assessing the average fractions of TH, CH, and AH from central blocks corresponds best to the average of the entire tumor. However, information on intratumor heterogeneities is lost, especially when considering tumors of substantially different volumes.

Basal HIF-1α expression levels are not predictive for radiosensitivity of human cancer cell lines.

BACKGROUND AND PURPOSE: High levels of hypoxia inducible factor (HIF)-1α in tumors are reported to be associated with tumor progression and resistance to therapy. To examine the impact of HIF-1α on radioresistance under normoxia, the sensitivity towards irradiation was measured in human tumor cell lines that differ significantly in their basal HIF-1α levels. MATERIAL AND METHODS: HIF-1α levels were quantified in lysates of H1339, EPLC-272H, A549, SAS, XF354, FaDu, BHY, and CX- tumor cell lines by ELISA. Protein levels of HIF-1α, HIF-2α, carbonic anhydrase IX (CA IX), and GAPDH were assessed by Western blot analysis. Knock-down experiments were performed using HIF-1α siRNA. Clonogenic survival after irradiation was determined by the colony forming assay. RESULTS: According to their basal HIF-1α status, the tumor cell lines were divided into low (SAS, XF354, FaDu, A549, CX-), intermediate (EPLC-272H, BHY), and high (H1339) HIF-1α expressors. The functionality of the high basal HIF-1α expression in H1339 cells was proven by reduced CA IX expression after knocking-down HIF-1α. Linear regression analysis revealed no correlation between basal HIF-1α levels and the survival fraction at either 2 or 4 Gy in all tumor cell lines investigated. CONCLUSION: Our data suggest that basal HIF-1α levels in human tumor cell lines do not predict their radiosensitivity under normoxia.

Adipokine expression in brown and white adipocytes in response to hypoxia.

BACKGROUND: Adipose tissue has emerged as an important endocrine regulator by secreting hormones referred to as adipokines. Recent studies showed that adipose tissue considerably responds to hypoxia. Although the impact of white adipose tissue on regulative processes is established, the importance of brown adipose tissue in adults has emerged just recently. METHODS: Brown (BA) and white adipocytes (WA) were cultured either in the presence of chemical hypoxia-mimetics or under hypoxic atmosphere of 1% oxygen. Expression of hypoxia-inducible factor 1α (HIF- 1α) was assessed by western blot. The expression levels of several known HIF-1α-regulated proteins [vascular endothelial growth factor (VEGF), leptin, adiponectin, and angiotensinogen (AGT)] were quantified. RESULTS: Both chemical hypoxia-mimetics and physical hypoxia led to increased nuclear HIF-1α expression and to decreased cytoplasmatic adiponectin in both cell types. In contrast, VEGF and AGT expression did not change upon hypoxic stimulation. Leptin was exclusively detectable in WA, while uncoupling-protein 1 (UCP-1) was expressed in BA only. CONCLUSIONS: WA and BA are sensitive to hypoxia, in which HIF-1α expression is induced. Protein expression of adiponectin is hypoxia-dependent, whereas AGT, VEGF, leptin, and UCP-1 expression do not change secondary to hypoxia.

Purified monocyte-derived angiogenic substance (angiotropin) induces controlled angiogenesis associated with regulated tissue proliferation in rabbit skin.

Angiotropin is a differentiation factor for microvascular endothelial cells isolated from serum-free cultures of lectin-activated, porcine monocytes. We used an ear lobe model in rabbits, single intradermal injection of angiotropin to induce phenotypical changes of the endothelial cells in capillaries and postcapillary venules, vascular engorgement, and subsequent angiogenesis in dose-dependent manner. The vascular changes are associated with epidermal and stromal cell proliferation. Angiogenesis and tissue proliferation occur in the absence of tissue necrosis and do not lead to scar formation. Angiotropin-induced angiogenesis is not inhibited by local dexamethasone although it involves a defined turnover of inflammatory cells. Proliferation is transient and regressive events follow. The overall tissue reaction resembles changes found in the undamaged skin margin of a primary healing wound during the inflammatory/proliferative phase. From these observations we conclude that angiotropin is an important secretory product of activated peripheral macrophages that triggers inflammatory and proliferative reactions in wound healing by activating microvascular endothelial cells.

ESPEN expert group recommendations for action against cancer-related malnutrition.

Patients with cancer are at particularly high risk for malnutrition because both the disease and its treatments threaten their nutritional status. Yet cancer-related nutritional risk is sometimes overlooked or under-treated by clinicians, patients, and their families. The European Society for Clinical Nutrition and Metabolism (ESPEN) recently published evidence-based guidelines for nutritional care in patients with cancer. In further support of these guidelines, an ESPEN oncology expert group met for a Cancer and Nutrition Workshop in Berlin on October 24 and 25, 2016. The group examined the causes and consequences of cancer-related malnutrition, reviewed treatment approaches currently available, and built the rationale and impetus for clinicians involved with care of patients with cancer to take actions that facilitate nutrition support in practice. The content of this position paper is based on presentations and discussions at the Berlin meeting. The expert group emphasized 3 key steps to update nutritional care for people with cancer: (1) screen all patients with cancer for nutritional risk early in the course of their care, regardless of body mass index and weight history; (2) expand nutrition-related assessment practices to include measures of anorexia, body composition, inflammatory biomarkers, resting energy expenditure, and physical function; (3) use multimodal nutritional interventions with individualized plans, including care focused on increasing nutritional intake, lessening inflammation and hypermetabolic stress, and increasing physical activity.

Tumor hypoxia: definitions and current clinical, biologic, and molecular aspects.

Tissue hypoxia results from an inadequate supply of oxygen (O(2)) that compromises biologic functions. Evidence from experimental and clinical studies increasingly points to a fundamental role for hypoxia in solid tumors. Hypoxia in tumors is primarily a pathophysiologic consequence of structurally and functionally disturbed microcirculation and the deterioration of diffusion conditions. Tumor hypoxia appears to be strongly associated with tumor propagation, malignant progression, and resistance to therapy, and it has thus become a central issue in tumor physiology and cancer treatment. Biochemists and clinicians (as well as physiologists) define hypoxia differently; biochemists define it as O(2)-limited electron transport, and physiologists and clinicians define it as a state of reduced O(2) availability or decreased O(2) partial pressure that restricts or even abolishes functions of organs, tissues, or cells. Because malignant tumors no longer execute functions necessary for homeostasis (such as the production of adequate amounts of adenosine triphosphate), the physiology-based definitions of the term "hypoxia" are not necessarily valid for malignant tumors. Instead, alternative definitions based on clinical, biologic, and molecular effects that are observed at O(2) partial pressures below a critical level have to be applied.

Effects of hydralazine-induced vasodilation on the energy metabolism of murine tumors studied by in vivo 31P-nuclear magnetic resonance spectroscopy.

The effects of hydralazine on tumor energy metabolism and on some cardiovascular parameters were measured. Tumor energy metabolism was studied in C3Hf/Sed mice with isotransplants of a spontaneous murine fibrosarcoma (FSaII, congruent to 100 mm3 in volume) and 31P-NMR. Cardiovascular parameters were measured in anesthetized C3Hf/Sed mice via intracarotid catheter. Hydralazine doses of 0.25 mg/kg given ip caused an increase of the phosphocreatine to inorganic phosphate ratio (PCr: Pi) in 5 of 6 animals. These doses had minimal effects on mean arterial blood pressure, though there may have been an increased cardiac output due to a decreased afterload. Hydralazine doses greater than or equal to 2.0 mg/kg given ip were associated with a decrease in PCr, nucleotide triphosphate, and pH, and an increase in Pi (P less than .01 for control vs. 10 mg hydralazine/kg). This substantial decrease in high-energy phosphates was associated with a pronounced decrement in mean arterial blood pressure. These findings provide a rational basis for the study in experimental systems of hydralazine-induced enhancement of cell killing by hyperthermia and by agents toxic to hypoxic cells. Further, these results can be taken as a sign that hydralazine should be used with care in patients undergoing radiation treatment.

Metabolic imaging in microregions of tumors and normal tissues with bioluminescence and photon counting.

A method has been developed for metabolic imaging on a microscopic level in tumors, tumor spheroids, and normal tissues. The technique makes it possible to determine the spatial distribution of glucose, lactate, and ATP in absolute terms at similar locations within tissues or cell aggregates. The substrate distributions are registered in serial cryostat sections from tissue cryobiopsies or from frozen spheroids with the use of bioluminescence reactions. The light emission is measured directly by a special imaging photon counting system enabling on-line image analysis. The technique has been applied to human breast cancer xenografts, to spheroids originating from a human colon adenocarcinoma, and to skeletal rat muscle. Preliminary data obtained indicate that heterogeneities in the substrate distributions measured are much more pronounced in tumors than in normal tissue. There was no obvious correlation among the three quantities measured at similar locations within the tissues. The distribution of ATP corresponded well with the histological structure of larger spheroids; values were low in the necrotic center and high in the viable rim of these cell aggregates.

Oxygenation status of primary and recurrent squamous cell carcinomas of the vulva.

INTRODUCTION: Cancers of the vulva are relatively rare and, therefore, little is known about the pathophysiological role of tumor oxygenation in this entity. METHODS: Data are presented on the oxygenation status of primary (n = 15) and recurrent (n = 19) cancers of the vulva, as measured by the Eppendorf pO2 histography system. RESULTS: Contrary to other tumor entities, no significant differences in the oxygenation status between primary (median pO2 = 13 mmHg; hypoxic fraction < or = 5 mmHg = 37%) and recurrent (median pO2 = 11 mmHg; hypoxic fraction < or = 5 mmHg = 45%) tumors were found. Oxygenation was significantly lower in cancers of the vulva than in the subcutis. Anemic patients had significantly poorer tumor oxygenation compared with patients whose cHb values were within the normal range (p = 0.02). CONCLUSIONS: The oxygenation of vulvar cancers is similar to other tumor entities, but does not show more severe hypoxia in recurrent cases. Anemia is associated with a poorer oxygenation status in vulvar cancers, whereas in the normal tissue no impact of cHb values on the median pO2 was observed.

Role of hypovolemic hemoconcentration in dose-dependent flow decline observed in murine tumors after intraperitoneal administration of glucose or mannitol.

Responses of tumor microcirculation (RBC flux) to i.p. glucose or mannitol injections were studied in early generation isotransplants of a spontaneous C3Hf/Sed mouse fibrosarcoma (FSaII). RBC flux in superficial tumor microregions was assessed using laser Doppler flowmetry. After administration of glucose or mannitol (a nonmetabolized sugar alcohol), a dose-dependent reduction in laser Doppler flow, and a dose-dependent increase in systemic hematocrit occurred concurrently. Maximum flow reductions induced by i.p. glucose or mannitol were statistically indistinguishable for equal osmotic load. Maximum decreases in RBC flux for glucose or mannitol were 20 and 25% (1.25 mg/g i.p.), 42 and 48% (2.5 mg/g i.p.), 72 and 60% (5 mg/g i.p.), and 80 and 75% (10 mg/g i.p.), respectively. Maximum increases in systemic hematocrit ranged from 18% (1.25 mg/g glucose i.p.) to 33% (10 mg/g glucose i.p.). Examination of RBC count, blood hemoglobin concentration, and fluid accumulation in the abdominal cavity after glucose or mannitol administration were all compatible with a significant shift of intravascular/extracellular water into the abdominal cavity with resultant systemic hypovolemic hemoconcentration. RBC volume and mean hemoglobin content of RBC remained unchanged with glucose loading. The data suggest that reductions in laser Doppler flow are predominantly caused by hypovolemic hemoconcentration following i.p. administration of hyperosmolar sugar solutions. Changes in laser Doppler flow due to specific glucose-mediated or glucose-related phenomena are probably of minor importance in the murine tumor system investigated. Future studies on murine tumors, examining for specific effects of glucose on metabolism and/or therapy, should not use i.p. administration of hyperosmolar solutions.

Effect of intraperitoneal versus intravenous glucose administration on laser Doppler flow in murine FSaII tumors and normal skin.

The effects of i.p. versus i.v. glucose administration on laser Doppler flow (LDF) were studied in peripheral tissue areas of murine FSaII tumors implanted s.c. in the hind foot dorsum and in normal skin of conscious C3Hf/Sed mice. LDF was monitored prior to and continuously for 90 min following the administration of glucose, galactose, or mannitol at doses of 5 or 10 mg/g. Results showed that i.p. administration of hyperosmolar solutions was followed by a substantial, dose-dependent flow reduction which was indistinguishable for the various agents at equal osmotic load, and similar in tumor tissue and normal skin. Reductions in LDF are, therefore, primarily caused by hypovolemic hemoconcentration following i.p. administration of hyperosmolar sugar solutions. In contrast, i.v. administration of these solutions at 5 mg/g caused an initial flow increase (most probably due to a transient hypervolemic hemodilution), with a return to baseline readings within 5-10 min. At 10 mg/g i.v., a biphasic change in LDF occurred with an initial, temporary increase and a significant decline thereafter with no recovery within the observation period. This drop in LDF most probably is due to a decrease in cardiac output and an increase in viscous resistance to flow. Since comparable changes were observed with all agents and in both tissues investigated, it is concluded that the alterations in flow pattern following injection of hyperosmolar solutions are neither glucose nor tissue specific. Glucose- or tumor-specific effects, if present at all, must be of secondary importance in the animal model chosen.

Blood flow, oxygen and nutrient supply, and metabolic microenvironment of human tumors: a review.

The objective of this review article is to summarize current knowledge of blood flow and perfusion-related parameters, which usually go hand in hand and in turn define the cellular metabolic microenvironment of human malignancies. A compilation of available data from the literature on blood flow, oxygen and nutrient supply, and tissue oxygen and pH distribution in human tumors is presented. Whenever possible, data obtained for human tumors are compared with the respective parameters in normal tissues, isotransplanted or spontaneous rodent tumors, and xenografted human tumors. Although data on human tumors in situ are scarce and there may be significant errors associated with the techniques used for measurements, experimental evidence is provided for the existence of a compromised and anisotropic blood supply to many tumors. As a result, O2-depleted areas develop in human malignancies which coincide with nutrient and energy deprivation and with a hostile metabolic microenvironment (e.g., existence of severe tissue acidosis). Significant variations in these relevant parameters must be expected between different locations within the same tumor, at the same location at different times, and between individual tumors of the same grading and staging. Furthermore, this synopsis will attempt to identify relevant pathophysiological parameters and other related areas future research of which might be most beneficial for designing individually tailored treatment protocols with the goal of predicting the acute and/or long-term response of tumors to therapy.

Dose-dependent effects of hydralazine on microcirculatory function and hyperthermic response of murine FSall tumors.

The effects of the vasodilator hydralazine (HYD) on microcirculatory function and hyperthermic response were studied in early generation isotransplants of a spontaneous C3Hf/Sed mouse fibrosarcoma (FSall). Red blood cell flux (RBC flux) in superficial tumor regions was assessed using laser Doppler flowmetry. A differential microcirculatory response was seen between tumor and normal skin after 0.25 micrograms/g i.p. HYD, the tumor showing a transient increase in flow and the skin remaining almost stable. At 1.0 micrograms/g i.p., the differential response continued, this time with a transient fall in tumor blood flow but again no change in skin flow. High dose hydralazine (10.0 micrograms/g i.p.) was associated with a dramatic and prolonged decrease in tumor blood flow but a lesser and only transient decline in skin flow. Identical doses of hydralazine were given 30 min prior to heat treatment (43.5 degrees C for 15, 30, or 60 min). Tumor growth was measured daily and compared to controls (HT without hydralazine). Hydralazine at 0.25 micrograms/g i.p. did not affect heat induced growth delay. At 1.0 micrograms/g i.p., it significantly increased growth delay upon heat exposures of 15 min, but not after 30 or 60 min HT. Hydralazine at 10 micrograms/g i.p. increased growth delay for all heat doses (P less than 0.05). Hydralazine alone had no influence on growth delay of sham-heated tumors. The results obtained clearly indicate that tumor and normal tissues have microcirculatory differences in the time-course, degree and/or direction of response after hydralazine, and that hydralazine has potential for increasing the response of tumor to HT.

Oxygenation of carcinomas of the uterine cervix: evaluation by computerized O2 tension measurements.

Direct oxygen partial pressure (pO2) readings in cancers of the cervix and in the normal cervix of nulliparous or parous women were obtained using a computerized pO2 histography system. The oxygenation status of the tumors was evaluated as a function of clinical staging and histological grading. pO2 measurements were performed with a customized electrode system in conscious pre- and postmenopausal, untreated patients with well-defined arterial blood gas status. With this technique, pO2 measurements in the normal cervix of nulliparous women resulted in oxygenation patterns which were characteristic for normal, adequately supplied tissues (median pO2, 48 mm Hg) with approximately 1% of the pO2 values grouped between zero and 2.5 mm Hg, i.e., in a range with less than half-maximum radiosensitivity. As a rule, the mean (and median) pO2 values were distinctly lower in the normal cervix of parous women (most probably due to scar formation following vaginal delivery) and in malignancies. In the normal cervix of parous women the median pO2 value was 13 mm Hg (with approximately 14% of the pO2 readings in the lowest class), 14 mm Hg in International Federation of Gynecologists and Obstetricians I/II tumors (2% of the readings in the lowest pO2 class), and 11 mm Hg in International Federation of Gynecologists and Obstetricians III/IV cancers (1% of the pO2 data in the lowest class). To date, 5 of 18 cervical cancers exhibited pO2 values between zero and 2.5 mm Hg. The oxygenation pattern in cervical cancers and the occurrence of hypoxia and/or anoxia did not correlate with either the clinical stages and histological grades or with a series of clinically relevant parameters (e.g., tumor size). No significant differences were found between pre- and postmenopausal tumors, between squamous cell carcinomas and adenocarcinomas, and between endophytic or exophytic tumors. From these studies there is clear indication that the oxygenation status of individual tumors cannot be predicted on the basis of staging and/or grading, predominantly because of the pronounced tumor-to-tumor variabilities. Evaluation of the tissue oxygenation of individual tumors is thus mandatory to prove that tumor oxygenation can predict the overall prognosis and/or treatment outcome.