Anemia: a problem or an opportunity in radiotherapy?

Tumor hypoxia: From basic knowledge to therapeutic implications

Diminished oxygen availability, termed hypoxia, within solid tumors is one of the most common characteristics of cancer. Hypoxia shapes the landscape of the tumor microenvironment (TME) into a pro-tumorigenic and pro-metastatic niche through arrays of pathological alterations such as abnormal vasculature, altered metabolism, immune-suppressive phenotype, etc. In addition, emerging evidence suggests that limited efficacy or the development of resistance towards antitumor therapy may be largely due to the hypoxic TME. This review will focus on summarizing the knowledge about the molecular machinery that mediates the hypoxic cellular responses and adaptations, as well as highlighting the effects and consequences of hypoxia, especially for angiogenesis regulation, cellular metabolism alteration, and immunosuppressive response within the TME. We also outline the current advances in novel therapeutic implications through targeting hypoxia in TME. A deep understanding of the basics and the role of hypoxia in the tumor will help develop better therapeutic avenues in cancer treatment.

Therapeutic Modification of Hypoxia

Regions of reduced oxygenation (hypoxia) are a characteristic feature of virtually all animal and human solid tumours. Numerous preclinical studies, both in vitro and in vivo, have shown that decreasing oxygen concentration induces resistance to radiation. Importantly, hypoxia in human tumours is a negative indicator of radiotherapy outcome. Hypoxia also contributes to resistance to other cancer therapeutics, including immunotherapy, and increases malignant progression as well as cancer cell dissemination. Consequently, substantial effort has been made to detect hypoxia in human tumours and identify realistic approaches to overcome hypoxia and improve cancer therapy outcomes. Hypoxia-targeting strategies include improving oxygen availability, sensitising hypoxic cells to radiation, preferentially killing these cells, locating the hypoxic regions in tumours and increasing the radiation dose to those areas, or applying high energy transfer radiation, which is less affected by hypoxia. Despite numerous clinical studies with each of these hypoxia-modifying approaches, many of which improved both local tumour control and overall survival, hypoxic modification has not been established in routine clinical practice. Here we review the background and significance of hypoxia, how it can be imaged clinically and focus on the various hypoxia-modifying techniques that have undergone, or are currently in, clinical evaluation.

EPOETIN A ALFA IN RADIOTERAPIA

Sixty per cent of oncologic patients need radiation therapy for cure or palliation. In fact, in most neoplastic diseases, a better local control positively impacts on disease-free survival and overall survival. The efficacy of radiotherapy depends on several factors: while some are tumor-related, others are host-related.

Radiobiological phenomena are also important: ionizing radiation is responsible for cell damage (double rupture of DNA chains), mostly an indirect mechanism with the formation of free radicals. Their toxic action is enhanced by the oxygen partial pressure at the cellular level.

A number of studies have confirmed that good tissue oxygenation is a function of a high hemoglobin level in the peripheral blood (Hb≥13g/dL). Unfortunately, these values are rarely present in oncologic patients due to the disease-related toxicosis as well as to the therapy induced hematologic toxicity.

The treatment of anemia is free of risk for the recent developments in technology which with gene cloning and the technique of recombinant DNA has allowed the production of human recombinant erythropoietin.

Erythropoietin is produced by the interstitial cells of renal tubules in response to hypoxia. It prevents apoptosis and promotes erythroid proliferation and differentiation with consequent reticulocyte release and hemoglobin synthesis.

It is not completely understood whether the efficacy of radiotherapy depends on hemoglobin values present at the start of irradiation (often less than 12-13 g/dL) or on the higher ones observed during and at the end of radiotherapy.

Therefore, preventive systemic erythropoietin therapy in non anemic patients in terms of costs/benefits is at present non sustainable.

To the contrary, in patients undergoing radiotherapy to extended fields or aggressive multimodal treatments, for the higher risk of anemia, the early use of this treatment can be hypothesized in case of initial anemia to improve therapy compliance and prevent negative conditioning of results.

Keeping in mind that grade 1 minimum toxicity for red cells, according to the Radiation Therapy Oncology Group (RTOG) is equal to 11gHb/dL we think that this value can be considered as cutoff to start erythropoietin therapy.

DAHANCA 10 - Effect of darbepoetin alfa and radiotherapy in the treatment of squamous cell carcinoma of the head and neck. A multicenter, open-label, randomized, phase 3 trial by the Danish head and neck cancer group

PURPOSE

To evaluate if correction of low hemoglobin (Hb) levels by means of darbepoetin alfa improves the outcomes of radiotherapy in patients with squamous cell carcinoma of the head and neck (HNSCC).

PATIENTS AND METHODS

Patients eligible for primary radiotherapy and who had Hb values below 14.0 g/dl were randomized to receive accelerated fractionated radiotherapy with or without darbepoetin alfa. Patients also received the hypoxic radiosensitizer nimorazole. Darbepoetin alfa was given weekly during radiotherapy or until the Hb value exceeded 15.5 g/dl.

RESULTS

Following a planned interim analysis which showed inferiority of the experimental treatment the trial was stopped after inclusion of 522 patients (of a planned intake of 600). Of these, 513 were eligible for analysis (254 patients treated with darbepoetin alfa and 259 patients in the control group). Overall, the patients were distributed according to the stratification parameters (gender, T and N staging, tumor site). Treatment with darbepoetin alfa increased the Hb level to the planned value in 81% of the patients. The compliance was good without excess serious adverse events. The results showed a poorer outcome with a 5-year cumulative loco-regional failure rate of 47% vs. 34%, Hazard Ratio (HR): 1.53 [1.16-2.02], for the darbepoetin alfa vs. control arm, respectively. This was also seen for the endpoints of event-free survival (HR: 1.36 [1.09-1.69]), disease-specific death (HR: 1.43 [1.08-1.90]), and overall survival (HR: 1.30 [1.02-1.64]). There was no enhanced risk of cardio-vascular events observed in the experimental arm or any significant differences in acute or late radiation related morbidity. All univariate analyses were confirmed in a multivariate setting.

CONCLUSION

Correction of the Hb level with darbepoetin alfa during radiotherapy of patients with HNSCC resulted in a significantly poorer tumor control and survival.

Improved recurrence-free survival with ARCON for anemic patients with laryngeal cancer

PURPOSE

Anemia is associated with poor tumor control. It was previously observed that accelerated radiotherapy combined with carbogen breathing and nicotinamide (ARCON) can correct this adverse outcome in patients with head and neck cancer. The purpose of this study was to validate this observation based on data from a randomized trial.

EXPERIMENTAL DESIGN

Of 345 patients with cT2-4 laryngeal cancer, 174 were randomly assigned to accelerated radiotherapy and 171 to ARCON. Hemoglobin levels, measured before treatment, were defined as low when <7.5 mmol/L for women and <8.5 mmol/L for men. The hypoxia marker pimonidazole was used to assess the oxygenation status in tumor biopsies. Data were analyzed 2 years after inclusion of the last patient.

RESULTS

Pretreatment hemoglobin levels were available and below normal in 27 of 173 (16%) accelerated radiotherapy and 27 of 167 (16%) ARCON patients. In patients with normal pretreatment, hemoglobin levels treatment with ARCON had no significant effect on 5-year loco-regional control (LRC, 79% versus 75%; P = 0.44) and disease-free survival (DFS, 75% vs. 70%; P = 0.46) compared with accelerated radiotherapy. However, in patients with low pretreatment, hemoglobin levels ARCON significantly improved 5-year LRC (79% vs. 53%; P = 0.03) and DFS (68% vs. 45%; P = 0.04). In multivariate analysis including other prognostic factors, pretreatment hemoglobin remained prognostic for LRC and DFS in the accelerated radiotherapy treatment arm. No correlation between pretreatment hemoglobin levels and pimonidazole uptake was observed.

CONCLUSION

Results from the randomized phase III trial support previous observations that ARCON has the potential to correct the poor outcome of cancer patients with anemia (ClinicalTrials.gov number, NCT00147732).

Importance of hemoglobin concentration and its modification for the outcome of head and neck cancer patients treated with radiotherapy

INTRODUCTION

Hypoxia induced radioresistance has been acknowledged for decades. One of the indirect evidences of the influence of hypoxia on radiation response comes from the observations of a correlation between tumor control and hemoglobin level. This review examines the clinical data on the prognostic and predictive role of hemoglobin level and hemoglobin manipulation in radiotherapy of squamous cell carcinomas of the head and neck, a tumor type where hypoxic radioresistance have been previously documented.

THE INFLUENCE OF HEMOGLOBIN CONCENTRATION ON TUMOR OXYGENATION AND OUTCOME

The aim is to evaluate the existing literature for information of the influence of hemoglobin concentration and hemoglobin modifications on tumor oxygenation and outcome in head and neck squamous cell cancer patients. The data from several randomized trials show that while most studies have confirmed the prognostic value of hemoglobin, increasing the hemoglobin level through transfusion or erythropoietin stimulation did not result in improved outcome for patients with low initial hemoglobin levels. Clinical studies showed that smoking reduced the oxygen carrying capacity of the blood through formation of carboxyhemoglobin, and lead to poorer response to radiotherapy in smokers compared to non-smokers. Smoking also increased the risk of the development of secondary cancers.

CONCLUSION AND FUTURE PERSPECTIVES

In conclusion, low hemoglobin is a significant negative prognostic factor for radiotherapy of head and neck cancer. Correction of pre-treatment low hemoglobin by blood transfusion and/or erythropoietin stimulating agents does, however, not improve the outcome. Smoking leads to a decrease in effective hemoglobin and poorer treatment outcome. Smoking should be avoided in order to improve the therapeutic efficacy of radiotherapy and development of other smoking-related diseases and/or secondary cancers.

Effect of smoking on oxygen delivery and outcome in patients treated with radiotherapy for head and neck squamous cell carcinoma--a prospective study

BACKGROUND

Head and neck cancer patients with high hemoglobin respond better to irradiation compared to patients with low hemoglobin possibly due to hypoxia induced radioresistance. The hemoglobin level is, however, a crude indicator of the amount of oxygen available to the tissue and may be influenced by a number of factors, smoking being of potential importance. The aim of the present study was to examine the effect of smoking on available oxygen to tumors and the effect on outcome in head and neck cancer patients treated with radiotherapy in a prospective study.

MATERIALS AND METHODS

A total of 232 consecutive patients with squamous cell carcinoma of the larynx, pharynx and oral cavity completed questionnaires on smoking habits prior to treatment. Venous blood samples were collected before and/or during treatment to determine the hemoglobin and carboxyhemoglobin level. Patients were treated with primary curative radiotherapy 62-68 Gy, 2 Gy/fx, 5 fx/week.

RESULTS

All but 12 patients had a history of smoking, 35 were long term quitters, 23 recent quitters, 54 moderate smokers and 108 heavy smokers (>1 pack/day). There was no relationship between total hemoglobin and carboxyhemoglobin, but effective hemoglobin and carboxyhemoglobin were linearly correlated. The amount of carboxyhemoglobin increased with increasing smoking status. Actuarial 5-year univariate analysis showed that heavy smokers had a significantly reduced probability of loco-regional control (44% vs. 65%, p = 0.001), disease-specific (56% vs. 77%, p = 0.003) and overall survival (39% vs. 66%, p = 0.0004) compared to non-smoking patients. Multivariate analyses showed that patients characterized as non-smokers, with low T and N classifications and high hemoglobin level had the best outcome measurements. A rise in carboxyhemoglobin significantly decreased the probability of loco-regional control and each additional pack year increased the risk of death. Smokers and former smokers develop secondary cancers.

CONCLUSION

The study showed a significant negative impact of smoking during radiotherapy for head and neck cancer and the risk of death was increased with each additional pack year of smoking. The effect on loco-regional control could be explained by a rise in carboxyhemoglobin level in smokers, e.g. a reduced oxygen supply to tumors. The data strongly advocate that smoking should be avoided in order to improve the therapeutic efficacy of radiotherapy and development of other smoking-related diseases and/or secondary cancers.

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

BACKGROUND AND PURPOSE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

Hypoxic tumors and their effect on immune cells and cancer therapy

The abnormal decrease or the lack of oxygen supply to cells and tissues is called hypoxia. This condition is commonly seen in various diseases such as rheumatoid arthritis and atherosclerosis, also in solid cancers. Pre-clinical and clinical studies have shown that hypoxic cancers are extremely aggressive, resistant to standard therapies (chemotherapy and radiotherapy), and thus very difficult to eradicate. Hypoxia affects both the tumor and the immune cells via various pathways. This review summarizes the most common effects of hypoxia on immune cells that play a key role in the anti-tumor response, the limitation of current therapies, and the potential solutions that were developed for hypoxic malignancies.

Microbubble-mediated oxygen delivery to hypoxic tissues as a new therapeutic device

Chitosan-coated oxygen microbubbles of average diameter 2.5 mum, narrow size distribution and spherical shape were prepared. A core-shell structure was evidenced by fluorescence microscopy using fluorescent microbubbles. Such microbubbles can be a therapeutic device for vehiculating oxygen to hypoxic tissues, provided they show proper permeability and diffusivity properties and are non-toxic. Our study proves that oxygen is efficiently delivered both in 'in vitro' and 'in vivo' preparations, and can be conveniently metabolized reversing the cellular hypoxic response. Moreover, toxic effects were investigated in human blood and in cultured cells and no evidence for them was found.

The radiation dose-response of the human spinal cord

PURPOSE

To characterize the radiation dose-response of the human spinal cord.

METHODS AND MATERIALS

Because no single institution has sufficient data to establish a dose-response function for the human spinal cord, published reports were combined. Requisite data were dose and fractionation, number of patients at risk, number of myelopathy cases, and survival experience of the population. Eight data points for cervical myelopathy were obtained from five reports. Using maximum likelihood estimation correcting for the survival experience of the population, estimates were obtained for the median tolerance dose, slope parameter, and alpha/beta ratio in a logistic dose-response function. An adequate fit to thoracic data was not possible. Hyperbaric oxygen treatments involving the cervical cord were also analyzed.

RESULTS

The estimate of the median tolerance dose (cervical cord) was 69.4 Gy (95% confidence interval, 66.4-72.6). The alpha/beta = 0.87 Gy. At 45 Gy, the (extrapolated) probability of myelopathy is 0.03%; and at 50 Gy, 0.2%. The dose for a 5% myelopathy rate is 59.3 Gy. Graphical analysis indicates that the sensitivity of the thoracic cord is less than that of the cervical cord. There appears to be a sensitizing effect from hyperbaric oxygen treatment.

CONCLUSIONS

The estimate of alpha/beta is smaller than usually quoted, but values this small were found in some studies. Using alpha/beta = 0.87 Gy, one would expect a considerable advantage by decreasing the dose/fraction to less than 2 Gy. These results were obtained from only single fractions/day and should not be applied uncritically to hyperfractionation.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Anemia correction in malignancy management: threat or opportunity?

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

AIMS

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Analysis of the prognostic impact of tumor embolization before definitive radiotherapy for cervical carcinoma

PURPOSE

To assess whether embolization compromises the radiocurability of primary cervical cancer.

METHODS AND MATERIALS

Two hundred fifty-four patients with primary cervical cancer (International Federation of Gynecology and Obstetrics [FIGO] stages IB: 47; II: 91; IIIB: 102; IV: 14) were treated with external beam irradiation and Ir-192 high-dose-rate brachytherapy over a period of 15 years. Of these, 24 patients (9.4%) (FIGO stages IB: 1; II: 8; IIIB: 12; IV: 3) had had bilateral embolization of the internal iliac arteries before referral. The median age of the entire cohort was 66 years (range, 34-85 years). Tumor size was >5 cm and paraortic nodes were enlarged (> or =1 cm) on pretreatment CAT scan in 39.4% and 9.1% of patients, respectively. All patients with hemoglobin levels (hb-l) < or =11 g/dL (28.3%) received packed red cell transfusions (PRCT) before and/or during radiotherapy in an attempt to maintain levels >11 g/dL throughout treatment. Cross-table tests were used to compare the distribution of FIGO stage, tumor size, lymph node status, and pretreatment and treatment hb-l of embolized and nonembolized patients. The impact of embolization, along with the above-listed tumor characteristics, on disease-specific survival (DSS), pelvic control (PC), and distant metastases-free survival (MFS) was determined by univariate and multivariate analyses.

RESULTS

Embolized patients presented at a statistically significant younger median age (55 vs. 67 years; p = 0.003), with larger tumors (66.7% vs. 36.5%; p = 0.007), and lower pretreatment hb-l (75% vs. 23.5%; p < 0.001) than nonembolized patients. There was no significant difference in stage distribution or lymph node status, and although embolized patients responded better to PRCT (50% vs. 29.6%), this difference was not statistically significant. Univariate analysis showed a trend toward decreased DSS (p = 0.09) and PC (p = 0.07) for embolized patients but no effect on MFS, whereas all other variables tested were significantly correlated with DSS, PC, and MFS (all p < 0.001). In the multivariate model, tumor embolization, FIGO stage, and pretreatment hb-l ceased to impact significantly on outcome. Tumor size remained the most powerful independent predictor for all endpoints tested, followed by treatment hb-l. Paraortic node status was significantly correlated with DSS and MFS.

CONCLUSION

Although a trend toward poorer DSS and PC was observed in embolized patients, no impact on radiocurability could be demonstrated in multivariate analysis after controlling for the major tumor characteristics and treatment hb-l.

The impact of anaemia on outcome in cancer

Anaemia is not an inconsequential side effect of cancer and its treatment should not be ignored. Current practice for anaemia management varies and its role in influencing outcome in cancer patients is under recognized. As a common complication of cancer, anaemia is prevalent in virtually all tumour types to varying degrees. Predictive factors for anaemia include baseline haemoglobin concentration, decrease in haemoglobin concentration within the first month of treatment, tumour type, duration of treatment and prior blood transfusions. Interest in the prognostic significance of anaemia in cancer patients has generated extensive clinical research. Data is now published in a wide range of tumour types confirming that anaemia is a negative prognostic indicator of outcome (e.g. survival, disease-free recurrence and local relapse), with the strongest association in patients receiving radiotherapy. The association has also been documented in patients undergoing chemotherapy and chemoradiation. A retrospective meta-analysis has shown an overall 65% increased risk of death associated with anaemia in cancer patients. The impact of anaemia as an independent prognostic factor for outcome may be mediated by several factors, however the emerging consensus is on the central role of tumour hypoxia. It has been nearly 50 years since R. Thomlinson and L. Gray (British Journal of Cancer 1955, 9: 539) first documented the existence of hypoxia in tumours and it is now well accepted that tumour hypoxia protects tumour cells from therapeutic damage directly by reducing the availability of oxygen-free radicals which are necessary for optimal impact of radiotherapy, certain chemotherapeutic agents and photodynamic therapy. The indirect effects include the impact of hypoxia on gene expression, which affects genetic stability, proliferation kinetics and cellular metabolism. There has been an emergence of preclinical and circumstantial data over recent years that are suggestive of the ability to correct the negative effect of anaemia on outcome by the use of repeated blood transfusions or recombinant human erythropoietin. This has led to some attempts to measure the impact on survival in cancer patients of treating anaemia, but early attempts have served to underline the complexity of the relationship and have produced unexpected results.

Impact of anemia in patients with head and neck cancer treated with radiation therapy

Locoregional recurrence remains a major obstacle to achieving a cure of locally advanced head and neck cancers, despite multimodality therapy. Multiple studies report that a low hemoglobin (Hgb) before or during radiation therapy is an important risk factor for poor locoregional disease control and survival. Anemia is common in the head and neck cancer population and is suspected to contribute to intratumoral hypoxia with resultant radioresistance. Although having a low Hgb level has been shown to be detrimental, it is unclear as to exactly what the threshold should be for low Hgb (studies in this area have used thresholds ranging from 9-14.5 g/dL). Quality-of-life studies suggest that correction of moderately severe anemia may result in significant gains. Optimal Hgb levels for improving outcomes may vary across and within tumor types, and this is an area that requires further evaluation. However, the correction of anemia may be a worthwhile strategy for radiation oncologists to improve local control and survival. This article reviews the impact of anemia on outcomes after radiotherapy of head and neck cancers.

Predictors of survival end points in patients with cancer of the cervix on long-term follow-up: inferences and implications from an audit of patients treated with a specific radiotherapy protocol

AIMS

An audit of patients with cancer of the cervix treated with a specified protocol of external beam radiotherapy (EXRT) followed by intracavitary brachytherapy (ICBT) was carried out to determine the prognosticators for major survival end points.

MATERIALS AND METHODS

Patients treated between 1991 and 2003 with a uniform protocol of EXRT (50 Gy/25 fractions/5 weeks) followed by high-dose-rate ICBT (18 Gy/3 fractions/3 weeks) were selected from the database. Various clinical and treatment parameters were evaluated for extent of locoregional response at completion of EXRT, namely absence or presence of gross residual tumour (AGRT and PGRT, respectively) and survival end points. These included locoregional disease-free survival (LDFS), disease-free survival (DFS) and overall survival (OS).

RESULTS

Of the 157 evaluable patients, 145 (92%) belonged to FIGO stages II and III. Eighty-three (53%) at completion of EXRT had AGRT, which was influenced by age and gross tumour features. The estimated 10-year LDFS, DFS and OS were 38.6%, 33.1% and 38.5%, respectively. Factors significant on univariate analysis for these survival end points were EXRT duration, ICBT time, overall treatment time (OTT) and EXRT response. On multivariate analysis, AGRT to EXRT, an OTT of < or = 67 days, and patients older than 50 years were the significant favourable determinants for all the above survival end points.

CONCLUSION

The audit highlights that younger people, especially those with bulky tumours that determine response to EXRT, are poor prognosticators for survival end points. They could perhaps benefit from treatment intensification regimens using chemoradiotherapy, provided that OTT is not unduly prolonged.

Impact of tumor hypoxia and anemia on radiation therapy outcomes

Local recurrence remains a major obstacle to achieving cure of many locally advanced solid tumors treated with definitive radiation therapy. The microenvironment of solid tumors is hypoxic compared with normal tissue, and this hypoxia is associated with decreased radiosensitivity. Recent preclinical data also suggest that intratumoral hypoxia, particularly in conjunction with an acid microenvironment, may be directly or indirectly mutagenic. Investigations of the prognostic significance of the pretreatment oxygenation status of tumors in patients with head and neck or cervical cancer have demonstrated that increased hypoxia, typically designated in these studies as pO(2) levels below 2.5-10 mm Hg, is associated with decreased local tumor control and lower rates of disease-free and overall survival. Hypoxia-directed therapies in the radiation oncology setting include treatment using hyperbaric oxygen, fluosol infusion, carbogen breathing, and electron-affinic and hypoxic-cell sensitizers. These interventions have shown the potential to increase the effectiveness of curative-intent radiation therapy, demonstrating that the strategy of overcoming hypoxia may be a viable and important approach. Anemia is common in the cancer population and is suspected to contribute to intratumoral hypoxia. A review of the literature reveals that a low hemoglobin level before or during radiation therapy is an important risk factor for poor locoregional disease control and survival, implying that a strong correlation could exist between anemia and hypoxia (ultimately predicting for a poor outcome). While having a low hemoglobin level has been shown to be detrimental, it is unclear as to exactly what the threshold for "low" should be (studies in this area have used thresholds ranging from 9-14.5 g/dl). Optimal hemoglobin and pO(2) thresholds for improving outcomes may vary across and within tumor types, and this is an area that clearly requires further evaluation. Nonetheless, the correction of anemia may be a worthwhile strategy for radiation oncologists to improve local control and survival.

Evaluation of the effect of routine packed red blood cell transfusion in anemic cervix cancer patients treated with radical radiotherapy

PURPOSE

It is well established that anemia predicts diminished radiocurability in cervix cancer. However, the therapeutic benefit of measures to correct the anemia remains controversial. The objective of this study was to determine the impact of routine transfusion in patients with hemoglobin level (hb-l) < or =11 g/dl.

METHODS AND MATERIALS

Since 1985, it has been departmental policy to attempt to correct hb-l < or =11 g/dl before and/or during radiotherapy by red blood cell transfusion (RBCT) in patients undergoing radical radiotherapy for primary cervix cancer. To assess the benefit of RBCT, the charts of 204 patients (FIGO: IB-IV) treated until 1997 were reviewed. Parameters analyzed for their impact on disease-specific survival (DSS), pelvic control (PC), and metastases-free survival (MFS) included pretreatment hb-l, treatment hb-l, stage, tumor size, and lymph node status. To determine any differences in outcome according to type of anemia, a separate analysis was performed, grouping patients by cause of anemia (tumor vs. other medical illness related).

RESULTS

Each of the parameters tested was significantly correlated with the end points studied in univariate analysis. Patients whose hb-l were corrected (18.5%) had an outcome that did not differ significantly from that of nontransfused patients, whereas DSS, PC, and MFS (all: p < 0.001) were significantly decreased in nonresponders to RBCT. Subgroup analysis showed no impact of hb-l in patients with other medical illness-related anemia (n = 12). In multivariate analysis treatment, but not pretreatment, hb-l remained predictive for DSS, PC, and MFS. Persistent anemia was associated with a significantly increased risk of death (relative risk: 2.1) and pelvic failure (relative risk: 2.4) compared with nontransfused patients. If only patients with tumor anemia were considered, the respective risks increased (2.7; 3.6). None of the patients with other causes of anemia recurred, whether or not their hb-l was maintained. Assessment of the therapeutic gain in patients who responded to RBCT showed improved PC (p = 0.02) and a trend toward increased DSS (p = 0.06), but no effect on MFS after adjustment for tumor size and lymph node status.

CONCLUSION

Treatment hb-l, in addition to tumor size and lymph node status, independently predicted outcome. Although our final multivariate analysis showed a therapeutic benefit for patients whose hb-l was corrected, the response to RBCT was disappointing. Results of our subgroup analysis suggest that the cause of anemia in patients with cervical cancer warrants in-depth investigation.

Anemia, hypoxia and transfusion in patients with cervix cancer: a review

BACKGROUND AND PURPOSE

With the recent development of hemopoietic growth factors and alternatives to transfusion, there has been a renewed interest in the relationships between anemia, tumor hypoxia and treatment outcome in a number of human malignancies. This review is intended to provoke a reconsideration of these issues and their effect on clinical trials, aimed at improving treatment outcome in patients with cervix cancer.

MATERIALS AND METHODS

Using data from the literature and from our own prospective series of tumor oxygenation in cervix cancer, we modeled the impact of anemia on tumor blood flow and hypoxia in animal models and human tumors, examined the relationship between anemia and hypoxia and treatment outcome in patients, and reviewed the impact of transfusion on tumor hypoxia and treatment outcome in cervix cancer.

RESULTS

Anemia may result in a significant reduction in oxygen delivery to tumors, but compensatory mechanisms reduce the impact on tumor oxygenation. Anemia is associated with inferior treatment outcome in cervix cancer, but hemoglobin levels prior to and during treatment are strongly correlated with tumor size, and this may explain the prognostic impact of anemia in older studies. Transfusion and erythropoietin ameliorate hypoxia in only a proportion of anemic patients. Critical analysis of the published data from the Princess Margaret Hospital randomized trial of transfusion in cervix cancer reveals that, when analyzed by intention-to-treat, transfusion did not result in a benefit to patients.

CONCLUSIONS

This review suggests that the relationships among anemia, hypoxia, transfusion and treatment outcome are complex. Further study of anemia as an independent prognostic factor is required and randomized studies of transfusion alternatives, such as erythropoietin, must be of sufficient size to detect small treatment effects.

Effect of nitroimidazole sensitizers on in vitro glycolytic metabolism of hypoxic squamous cell carcinoma

Two nitroimidazole compounds, misonidazole (MISO) and nimorazole (NIMO), were evaluated for their potential to modify uptake of [5,6-3H] 2-fluoro-2-deoxy-D-glucose (3H-FDG) in the human squamous carcinoma cell line UT-SCC-5 exposed to increasing levels of hypoxia. UT-SCC-5 cells were incubated with 0-10 mM of MISO or NIMO under normal or reduced oxygen concentrations of 20%, 1.5%, or 0% with 5% CO2 for 6 h, after which 74 KBq of 3H-FDG was added in media for 1 h. In the presence of normal concentrations of O2, both sensitizers increased 3H-FDG uptake by up to 178% (MISO) or 84% (NIMO) when compared with untreated cells. In anoxia, MISO decreased 3H-FDG uptake to 35% of that of control whereas NIMO-treated cells showed a respective decrease in tracer uptake to 62%. Clonogenic assays clearly indicated that MISO was toxic and NIMO moderately toxic for hypoxic cells, whereas both sensitizers exerted only a very modest effect on survival of fully oxygenated cells. Our findings indicate that nitroimidazole treatment consistently increases 3H-FDG uptake into UT-SCC-5 cells under normal oxygen concentrations. In hypoxia, the observed decrease in tracer uptake is dependent on both the level of ambient oxygen and drug concentration and may reflect both direct toxicity and inhibition of glycolysis. The observations may be useful for further applications of 18F-FDG positron emission tomography (PET) to monitor effects of hypoxic cell radiosensitizers on tumor metabolism in vivo.

The importance of hemoglobin levels during radiotherapy for carcinoma of the cervix

BACKGROUND

It is unclear whether blood transfusion can overcome the negative impact of anemia before or during radiotherapy (RT) in patients with carcinoma of the cervix. The objective of this retrospective study was to examine the impact of anemia and blood transfusion on 605 patients with carcinoma of the cervix treated with radical RT at 7 centers across Canada in 1989, 1990, and 1992.

METHODS

The data collected included hemoglobin (Hgb) levels from the time of diagnosis to the end of therapy; blood transfusions administered; and identifiable patient-, tumor-, and treatment-related factors. Survival, disease free survival, and pelvic control analyses were evaluated by univariate and multivariate analysis.

RESULTS

The median follow-up was 41 months (range, 0-92 months). Presenting Hgb level, average weekly nadir Hgb (AWNH) during RT, and blood transfusion were correlated significantly with local control, disease free survival, and overall survival on univariate analysis. However, the AWNH remained significant on multivariate analysis, whereas Hgb at presentation and blood transfusion did not. The 5-year survival was 74% for patients with an AWNH >/= 120 g/L, 52% for patients with AWNH levels 110-119 g/L inclusive, and 45% for patients with AWNH levels < 110 g/L (P < 0.0001). At each Hgb level, patients who were transfused and maintained a specific Hgb level had a survival rate that was not significantly different from patients who were at that level spontaneously. There was a significant reduction in both pelvic and distant recurrence (P < 0.0001 and P < 0.0006, respectively) in patients whose AWNH level during RT was >/= 120 g/L compared with < 120 g/L. A reduction in the rate of distant recurrence was observed in patients with and without pelvic recurrence.

CONCLUSIONS

AWNH is highly predictive of outcome for patients treated with RT for carcinoma of the cervix. Blood transfusion appears to overcome the negative prognostic effects of low presenting Hgb levels and AWNH levels.

Influence of erythropoietin on transfusion requirements in patients receiving preoperative chemoradiotherapy for rectal cancer

PURPOSE

Perioperative homologous blood transfusion has been suggested to have an adverse effect on survival in patients undergoing resection of colorectal cancers. Preoperative therapy is being increasingly used for rectal cancer patients and has an adverse effect on erythropoietic capacity. The objectives of this study were to evaluate the feasibility and safety of administration of recombinant human erythropoietin to patients receiving preoperative therapy for rectal cancer and to assess the impact of such treatment on blood transfusion requirements.

METHODS

The study was an open-label, Phase I and II, nonrandomized, two-center trial. All patients received 50.4 Gy of irradiation with 5-fluorouracil infusions. Ten patients diagnosed with rectal cancer received 250 U/kg of recombinant human erythropoietin subcutaneously three times per week during preoperative radiation and chemotherapy. Oral iron was given to patients receiving erythropoietin. Ten contemporaneously treated patients who received both radiation and chemotherapy were used as controls.

RESULTS

Of the 20 patients 13 were males; mean age was 64 years. Surgical procedures that patients underwent were abdominoperineal resection (14 patients), low anterior resection (4 patients), coloanal anastomosis (1 patient), or none (1 patient). There were no significant differences between groups in age, gender, stage or hemoglobin levels before therapy. No adverse reactions to erythropoietin were encountered. Hemoglobin levels were significantly higher in the treatment group during Weeks 1, 3, and 5 (P < 0.02 for each). Transfusion requirements were significantly decreased in patients who received erythropoietin (0.4 vs. 3.7 units; P < 0.0003).

CONCLUSIONS

The data showed that use of erythropoietin during preoperative therapy can prevent the decline in hemoglobin that commonly occurs during therapy. Further, this was not associated with adverse events and significantly decreased the need for perioperative blood transfusions. This suggests that the use of erythropoietin in support of a preoperative chemoradiotherapy regimen for patients with rectal cancer is safe and should be considered. Whether such transfusion avoidance will translate into a survival benefit in this setting will require a large, prospective, clinical trial.

Prognostic factors in patients with carcinoma of the uterine cervix treated with external beam irradiation and IR-192 high-dose-rate brachytherapy

PURPOSE

Prognostic factors in cancer of the cervix for patients treated with external beam irradiation (EBR) and low-dose-rate (LDR) brachytherapy have been characterized. However, despite the increasing use of high-dose-rate (HDR) intracavitary placements (ICP), few studies with adequate follow-up have analyzed prognostic factors. This study investigates pretreatment and treatment factors for their correlation with treatment outcome after EBR and HDR-ICP.

METHODS AND MATERIALS

Between September 1985 and December 1994, 181 patients with carcinoma of the cervix FIGO stages IB-IV received EBR and HDR brachytherapy. Hemoglobin (Hb) levels were maintained above a level of 11 g/dl during the treatment by transfusion. Patient age ranged from 34 to 84 years (median: 66). The median follow-up time for patients at risk is 69 months (range: 23-140). Pretreatment and treatment parameters analyzed to determine their prognostic value included age, FIGO stage, tumor size, tumor type and grade, pretreatment Hb level, number of HDR-ICP, total dose from HDR-ICP, overall dose to point A, and overall treatment time. Also evaluated was the prognostic value of enlarged lymph nodes noted on pretreatment CAT scan of the abdomen and pelvis. Endpoints studied in uni- and multivariate analyses were disease-specific survival (DSS), freedom from disease (FFD), pelvic control (PC), and probability of distant metastases (DM).

RESULTS

At 5 years the DSS, FFD, and PC rates for all patients were 60%, 58%, and 67%, respectively. The 5-year FFD by stage was: IB: 94%; II: 63%; IIIB: 43%; and IV: 0%. The PC rates were 94%, 66%, 59%, and 0%, respectively. In univariate analysis the prognostic factors identified for FFD were FIGO stage, tumor size, initial Hb level, and enlarged pelvic and/or paraaortic nodes (all: p < 0.0001). Age was inversely correlated with outcome (p = 0.0081). The 5-year FFD rates for tumors (< 3, > or = 3 < 6, > or = 6 cm) were 97%, 65%, and 24%; patients with initial Hb levels < or = 11g/dl had a FFD of 26% versus 69% for patients with levels > 11g/dl; and those with pelvic and/or paraaortal nodes > or = 1 cm had a survival of 32% versus 68% in patients with negative readings. The same factors were also prognostically significant for DSS, PC, and DM. Patients with persistent disease or pelvic failures had a significantly higher incidence of DM than patients in whom pelvic disease was controlled (p < 0.0001).Histological and treatment parameters including overall treatment time were not of prognostic significance for any of the endpoints studied. In multivariate analysis tumor size was the most powerful parameter for DSS, FFD, PC (p < 0.0001) and DM (p = 0.0001), followed by low initial Hb level (DSS: p = 0.0004, FFD: p = 0.0009, PC: p = 0.0012, DM: p = 0.0265), and enlarged pelvic and/or paraaortic nodes which were predictive for DSS (p = 0.0210) and DM (p = 0.0011).

CONCLUSION

This study confirms that prognostic factors for patients treated with HDR brachytherapy are similar to those reported in previous series that employed LDR brachytherapy. The significance of tumor size, pretreatment Hb level, and enlarged pelvic and/or paraaortic lymph nodes on CAT scan over FIGO stage of disease were demonstrated. Future prospective trials should be undertaken to confirm the validity of these factors and to elucidate their therapeutic implications.

Effect of subcutaneous recombinant human erythropoietin in cancer patients receiving radiotherapy: final report of a randomized, open-labelled, phase II trial

The purpose of this study was to determine the safety, efficacy and impact on quality of life of recombinant human erythropoietin (r-HuEPO) for cancer patients undergoing radiotherapy (RT). An open-labelled randomized design was used, with patients randomized to either treatment or control arms. Patients in the treatment arm received r-HuEPO given by subcutaneous injection at a dose of 200 units kg(-1) day(-1) plus oral iron supplements (ferrous sulphate 325 mg p.o. t.i.d.). Entry was restricted to patients with carcinoma of the lung, uterine cervix, prostate or breast who presented for RT with anaemia parameters reflective of 'the anaemia of chronic disease'. Radiotherapy policies (portals, doses, fraction size, etc.) were determined by the site and stage of disease. Complete blood counts (CBCs) were obtained weekly. The target level of haemoglobin was 15 g dl(-1) for men and 14 g dl(-1) for women. Quality of life (QOL) was assessed weekly by using an analogue scale to judge energy, activities of daily living and overall quality of life. Forty-eight patients were entered in the study, 24 in the treatment arm and 24 in the control arm. The prerandomization demographic characteristics and mean laboratory values were comparable in both arms. The mean haemoglobin at completion was 13.6 g dl(-1) for r-HuEPO-treated patients compared with 11.0 g dl(-1) for control subjects (P = 0.0012). Patients who received r-HuEPO demonstrated a mean weekly haemoglobin increase of 0.41 g dl(-1) compared with a decrease in mean haemoglobin level in controls for 6 of the 7 weeks of the study (mean weekly decrease of 0.073 g dl(-1)). Target levels of haemoglobin were achieved by 41.6% of r-HuEPO-treated patients compared with none of the control subjects. The mean platelet count declined in both arms of the study with RT but the decline from pretreatment was less rapid in r-HuEPO-treated patients (11.2% decrease) compared with controls (26.3% decrease) and was statistically significant during weeks 4-6. Toxicity was minor with only mild irritation at the injection site. Mean quality of life end points were superior in the treatment arm but not statistically significant. r-HuEPO had a beneficial effect on weekly haemoglobin levels in patients undergoing RT with response rates similar to other studies. There was also a less rapid decline in weekly platelet counts in r-HuEPO-treated patients compared with control subjects. Further studies are needed to address the optimum dose and scheduling as well as the impact of r-HuEPO on clinical outcomes.

A randomized double-blind phase III study of nimorazole as a hypoxic radiosensitizer of primary radiotherapy in supraglottic larynx and pharynx carcinoma. Results of the Danish Head and Neck Cancer Study (DAHANCA) Protocol 5-85

PURPOSE

A multicenter randomized and balanced double-blind trial with the objective of assessing the efficacy and tolerance of nimorazole given as a hypoxic radiosensitizer in conjunction with primary radiotherapy of invasive carcinoma of the supraglottic larynx and pharynx.

PATIENTS AND TREATMENT

Between January 1986 and September 1990, 422 patients (414 eligible) with pharynx and supraglottic larynx carcinoma were double-blind randomized to receive the hypoxic cell radiosensitizer nimorazole, or placebo, in association with conventional primary radiotherapy (62-68 Gy, 2 Gy per fraction, five fractions per week). The median observation time was 112 months.

RESULTS

Univariate analysis showed that the outcome (5-year actuarial loco-regional tumor control) was significantly related to T-classification (T1-T2 48% versus T3-T4 36%, P = 0.0008), neck-nodes (N- 53% versus N+ 33%), pre-irradiation hemoglobin (Hb) concentration (high 46% versus low 37%, P = 0.02) and sex (females 51% versus males 38%, P = 0.03). Overall the nimorazole group showed a significantly better loco-regional control rate than the placebo group (49 versus 33%, P = 0.002). A similar significant benefit of nimorazole was observed for the end-points of final loco-regional control (including surgical salvage) and cancer-related deaths (52 versus 41%, P = 0.002). This trend was also found in the overall survival but to a lesser, non-significant extent (26 versus 16%, 10-year actuarial values, P = 0.32). Cox multivariate regression analysis showed the most important prognostic parameters for loco-regional control to be positive neck nodes (relative risk 1.84 (1.38-2.45)), T3-T4 tumor (relative risk 1.65 (1.25-2.17)) and nimorazole (relative risk 0.69 (0.52-0.90)). The same parameters were also significantly related to the probability of dying from cancer. The compliance to radiotherapy was good and 98% of the patients received the planned dose. Late radiation-related morbidity was observed in 10% of the patients, irrespective of nimorazole treatment. Drug-related side-effects were minor and tolerable with transient nausea and vomiting being the most frequent complications.

CONCLUSION

Nimorazole significantly improves the effect of radiotherapeutic management of supraglottic and pharynx tumors and can be given without major side-effects.

Anemia of cancer

Cancer patients frequently develop anemia, due either to the cancer itself or to the effects of cancer-related therapy. Recent years have brought insights into both the pathogenesis of the anemia of cancer and the extent to which erythropoietin regulation participates in this process. Although transfusion therapy was the mainstay of therapy for symptomatic anemia in the past, clinical trials have demonstrated that recombinant human erythropoietin can alleviate both anemia and transfusion requirements in many cancer patients and may prove to have an important role in the treatment of cancer-related anemia in the future.

Evaluation of oxygenation status during fractionated radiotherapy in human nonsmall cell lung cancers using [F-18]fluoromisonidazole positron emission tomography

PURPOSE

Recent clinical investigations have shown a strong correlation between pretreatment tumor hypoxia and poor response to radiotherapy. These observations raise questions about standard assumptions of tumor reoxygenation during radiotherapy, which has been poorly studied in human cancers. Positron emission tomography (PET) imaging of [F-18]fluoromisonidazole (FMISO) uptake allows noninvasive assessment of tumor hypoxia, and is amenable for repeated studies during fractionated radiotherapy to systematically evaluate changes in tumor oxygenation.

METHODS AND MATERIALS

Seven patients with locally advanced nonsmall cell lung cancers underwent sequential [F-18]FMISO PET imaging while receiving primary radiotherapy. Computed tomograms were used to calculate tumor volumes, define tumor extent for PET image analysis, and assist in PET image registration between serial studies. Fractional hypoxic volume (FHV) was calculated for each study as the percentage of pixels within the analyzed imaged tumor volume with a tumor:blood [F-18]FMISO ratio > or = 1.4 by 120 min after injection. Serial FHVs were compared for each patient.

RESULTS

Pretreatment FHVs ranged from 20-84% (median 58%). Subsequent FHVs varied from 8-79% (median 29%) at midtreatment, and ranged from 3-65% (median 22%) by the end of radiotherapy. One patient had essentially no detectable residual tumor hypoxia by the end of radiation, while two others showed no apparent decrease in serial FHVs. There was no correlation between tumor size and pretreatment FHV.

CONCLUSIONS

Although there is a general tendency toward improved oxygenation in human tumors during fractionated radiotherapy, these changes are unpredictable and may be insufficient in extent and timing to overcome the negative effects of existing pretreatment hypoxia. Selection of patients for clinical trials addressing radioresistant hypoxic cancers can be appropriately achieved through single pretreatment evaluations of tumor hypoxia.

Tumor oxygenation in anemic rats: effects of erythropoietin treatment versus red blood cell transfusion

Anemia was induced in rats by the development of a hemorrhagic ascites. These animals also bore solid tumors (DS-sarcomas) on the hind foot dorsum. The effects of two methods for anemia correction on oxygenation in the solid tumors were compared in this study. Anemia was corrected either chronically by erythropoietin administration (1000 IU/kg) over 14 days (EPO) or acutely by transfusion with red blood cells (TR). Non-anemic and untreated anemic animals served as controls. Tumor oxygenation was determined in anesthetized animals using polarographic needle electrodes and pO2 histography. The reduction in hematocrit and hemoglobin content found in anemic animals could successfully be corrected either by EPO or by TR. Anemia resulted in a worsening of tumor oxygenation which could partially be reversed by EPO or TR in small tumors (< 1.4 ml). In larger tumors (> or = 1.4 ml), neither method of anemia correction resulted in significant changes in tumor oxygenation.

The effect of recombinant human erythropoietin treatment on tumour radiosensitivity and cancer-associated anaemia in the mouse

Recombinant human erythropoietin (rHuEpo) has recently become available for the treatment of chronic anaemia, including that associated with cancer. Carcinoma NT in CBA mice causes a progressive anaemia which can be overcome by daily injections of recombinant human erythropoietin (rHuEpo). This model was used to study the effect of haematocrit on tumour blood flow, growth rate and radiosensitivity, in mice with haematocrits ranging from approximately 38% (control) to 65% (20 U/day rHuEpo). Tumours showed a small but significant slowing in growth rate with higher haematocrit. In vitro studies showed rHuEpo had no direct effect on the growth of NT cells. Tumour blood flow was measured by two methods in each mouse (133Xe clearance and 86Rubidium uptake). Blood flow showed a tendency to decrease with increasing blood viscosity although this effect was not significant despite the large differences in haematocrit. Although tumour doubling time was prolonged despite the large differences in haematocrit. Although tumour doubling time was prolonged with increasing radiation dose, from 0 (sham irradiated) to 35 Gy, haematocrit was not found to influence the growth delay. This was attributed to adaptation of the tumour during the relatively slow change in the haematocrit. rHuEpo is being considered for clinical use in anaemic cancer patients. Our data suggest that this treatment will correct haematocrit with no effect on tumour radiosensitivity.

The "anti-pyrimidine effect" of hypoxia and brequinar sodium (NSC 368390) is of consequence for tumor cell growth

The rationale of the present study was to investigate the simultaneous effect of hypoxia and drugs with an "anti-pyrimidine effect" on tumor cell proliferation to evaluate putative changes in the sensitivity of cells to these kinds of chemotherapeutic treatment on reduced O2 tension. Pyrimidine de novo biosynthesis, at the stage of respiratory chain-dependent dihydroorotate dehydrogenase, was found to be a biochemical target site for oxygen deficiency as well as for Brequinar Sodium (6-fluoro-2-(2'-fluoro-1,1'-biphenyl-4-yl)-3-methyl-4-quinoline carboxylic acid sodium salt) (Brequinar). Increasing drug concentrations (0.1-50 microM) reduced the proliferation rate of in vitro cultured Ehrlich ascites tumor cells (IC50 = 0.25 microM). Decreasing concentrations of O2 reduced the proliferation rate (50% at approximately 3.5% O2). Brequinar at 2.5 microM stimulated the incorporation of exogenous [14C]uridine into RNA to 140 and 190% of controls, respectively, as a result of active salvage pathways, whereas it decreased the incorporation of [14C]NaHCO3 by the de novo pathway (to 20 and 5% of controls, respectively). Cells routinely grown in glucose-free, uridine-supplemented medium were resistant to 12.5 microM of the drug. The complete growth pattern of the tumor cells (increase in cell number and protein, RNA and DNA content of cultures during a 24-hr culture period) was examined (i) on reducing the O2 tension of the atmosphere stepwise from 20 to 1% O2; (ii) on addition of 0.125 microM Brequinar; and (iii) under both conditions. The combination was found to give an additive inhibitory effect under moderate hypoxia (5-20% O2) and a greater than additive effect if the oxygen tension was further reduced (1-5%).

A cytokinetic approach to determine the range of O2-dependence of pyrimidine(deoxy)nucleotide biosynthesis relevant for cell proliferation

In vitro cultured Ehrlich ascites tumour (EAT) cells were used because of the ease of their manipulation under different levels of hypoxia. They were used to clarify further the complex mechanism of oxygen-dependent cell proliferation. On reducing the oxygen concentration from 20% to lower levels (1-7%) an increase in the length of the population doubling time with concomitant reductions in protein, RNA and DNA content of cultures were observed. The incorporation of [14C]HCO3- into the RNA fraction of cells by de novo biosynthesis of uridine monophosphate (UMP) was reduced proportionally to the microenvironmental O2 tension. Uptake of this labelled precursor by cells in the presence of N-phosphonoacetyl-L-aspartate was found to be similarly inhibited. To correlate the reduction of cell growth under hypoxia with the functional pyrimidine supply, hypoxic cells were cultured in the presence of a balanced mixture of deoxynucleosides and/or uridine (100 microM deoxycytidine, 10 microM deoxyadenosine, 10 microM deoxyguanosine, 100 microM uridine). Above 3% O2 in the protective atmosphere, no improvement of growth parameters by the exogenous pyrimidinenucleotide precursors was obtained, whereas these compounds had a positive influence below this level. The increase in cell number was raised to about 60% of that of control cultures (20% O2) irrespective of the oxygen tension. In addition, when above 3% O2 the incorporation of HCO3- into RNA was comparable to that of controls, indicating that the pyrimidine de novo pathway is not a limiting factor in RNA biosynthesis. In conclusion, whereas at suboptimal O2 levels (5-7%) no correlation between pyrimidine metabolism and reduction of proliferation rate appears to exist, at low O2 concentrations (less than 3%) the rate of orotate/UMP production seems to be an important factor in the growth cessation of EAT cells; at critical O2 tensions (less than 1%) the lack of pyrimidine-deoxynucleosides substantially reduces cell cycle progression.

The prognostic value of hemoglobin and a decrease in hemoglobin during radiotherapy in laryngeal carcinoma

An association between a low Hb-content and a poor response on radiation therapy has been established in previous years, especially in patients with squamous cell carcinomas. Whether this is linked with hypoxic conditions of the tumour or associated with tumour volume, blood loss or other conditions, is not yet known for certain. Patients with small head and neck tumours seem to form an interesting group to study this issue because several factors can be ruled out. Therefore, a retrospective analysis of 306 patients with glottic or supraglottic carcinoma was performed, to identify whether the Hb-value was of prognostic importance and whether this was linked to other patient characteristics. All patients were treated with primary radiotherapy with doses ranging from 60 to 70 Gy in 6-7 weeks. It appeared that in glottic carcinoma, the disease-free survival was significantly worse in patients with a Hb-value below normal at the start or/and at the end of therapy (p = 0.09, p = 0.0012, respectively). In patients with supraglottic carcinoma, the above mentioned difference approved only for a Hb-value below normal at the end of treatment (p = 0.05). A decrease in Hb-level of greater than or equal to 0.5 mmol/l during therapy, regardless whether the Hb-values were within or beyond normal range, reduced the disease-free survival in patients with glottic carcinoma (p = 0.0125). In a multivariate analysis, the Hb-value at the end of treatment proved to be an independent prognostic factor after T- and N-classification. There was no relationship with nutritional condition of the patient, nor with the Karnofsky Performance scale.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of two fractions of radiation, delivered in air or in hyperbaric oxygen, on the Fib/T tumour in WHT mice pretreated with a hypoxic gas mixture

The response of the Fib/T tumour to equal fractions of radiation, spaced by an interval of 24 hours, was determined in tumour-bearing mice that were pretreated either with 8% oxygen for 48 h or with air. An increase in tumour cell kill occurred in the group of animals that received a low oxygen pretreatment. Tumour cell kill was further and significantly increased if mice were retained in the low oxygen environment for the 24-h interval between radiation fractions. Possible explanations for these findings are proposed and discussed. The effect of a 48 h 8% oxygen exposure in modifying the response of the Fib/T tumour to two fractions of radiation, both delivered in hyperbaric oxygen, was also investigated. The low oxygen pretreatment did not significantly alter the tumour response to radiation given under conditions of hyperbaric oxygenation.

In situ tumour radiosensitization induced by clofibrate administration: single dose and fractionated studies

It is generally accepted that hypoxia is a common occurrence in many experimental and human tumours and that it is a major cause of local failure after radiotherapy. Many attempts have been made over the last years to eliminate this problem. One of the manoeuvres to improve tumour oxygenation is to manipulate the binding affinity of oxygen (O2) and haemoglobin (Hb). Previous studies have shown that some antilipidaemic drugs (clofibrate and its analogues) can reduce the Hb/O2 binding affinity and sensitize various animal tumours to radiation. The present study evaluated the ability of clofibrate to sensitize in situ a mouse carcinoma (CaNT) to radiation. Clofibrate at 1.5 mmol/kg increased the tumour radiosensitivity, when it was administered per os 2-6 h before a single radiation dose or 2 to 4 h before each of 10 fractions in 5 days. In both the single dose and fractionated regimens, the radiosensitizing effect was drug dose-dependent, but was only statistically significant at doses from 1.0 to 2.0 mmol/kg. These results suggest that clofibrate may be an effective radiosensitizer at radiation doses that are clinically relevant. Further experiments need to be carried out to evaluate clofibrate analogues for their radiosensitizing properties. Clofibrate tolerable doses in man have to be determined first in order to know if clofibrate and analogues could play a role in the clinical management of tumours where hypoxia may limit the outcome of radiotherapy.

Should tumors be clamped in radiobiological fractionation experiments?

In radiobiological fractionation experiments tumors are often clamped during irradiation. This is done not only to facilitate the interpretation of the data by eliminating the influence of reoxygenation but also to avoid uncontrolled changes in the hypoxic fraction that are caused by anesthesia or stress from physical restraint. In this study it is shown that clamping of tumors during irradiation also affects repair, repopulation, and redistribution. From these results it is concluded that clamping of tumors during fractionated irradiation treatment does not appear to be an adequate measure to elucidate the mechanisms that determine tumor response to radiotherapy. Even some of the fundamental concepts of tumor radiobiology might contain some uncertainties, since they are often based on data resulting from clamped tumors.

Changes in tumour morphology with alterations in oxygen availability: further evidence for oxygen as a limiting substrate

The ability of cancer cells to survive at a distance from blood vessels should be dependent on the local supply of nutrients to each vessel. The corded growth of tumour cells around blood vessels within regions of necrosis in the RH carcinoma in the mouse allows the limit to which cells can be supported by individual vessels to be observed. The thickness of individual tumour cords was measured in conventionally stained tumour sections using a scanning technique to determine the distance between the blood vessel wall and the most distant viable cell adjacent to necrosis. Cord radius was found to vary with the oxygen supply conditions. Control animals had a mean radius of 105 +/- 2 microns while animals that had breathed 10% oxygen had significantly narrower cords (93 +/- 3 microns after 48 h) and animals breathing 100% oxygen had significantly wider cords (117 +/- 3 microns after 24 h). Mice made anaemic (mean hct. 28%) by phlebotomy and plasma transfusion had cord radii that were not significantly different from controls at any time up to 48 h. We conclude that this relatively slow growing mouse tumour is capable of rapid morphological adaptation (less than 3 h) to changes in nutrient availability and that oxygen is probably the limiting substrate.

The influence of chronic anaemia on the radiosensitivity of two mouse tumours

There is clear clinical evidence that tumours in anaemic patients are difficult to control with radiotherapy. We have studied the radiosensitivity of two transplantable mouse tumours, the SCCVII/St carcinoma and the KHT sarcoma in hosts made anaemic either with an iron poor diet or as a result of tumour growth. The haemoglobin level and haematocrits of mice on the low iron diet fell to about 60% of normal within 11 weeks. The number of clonogenic cells after a single X-ray dose of 20 Gy was slightly lower (P less than 0.05) in the anaemic animals (2.3 X 10(4) g-1) than in controls (5.2 X 10(4) g-1) though there was no significant difference in the surviving fractions. Mice bearing KHT tumours became anaemic with haematocrits falling to 65% of normal as their tumours grew from 300-1200 mg. A second 'test' tumour was implanted one week after the first 'anaemia-inducing' tumour so that estimates of radiosensitivity could all be carried out on tumours within the same size range (150-300 mg). Radiosensitivity was significantly greater in the most anaemic hosts with 2.2 X 10(4) cells g-1 surviving a dose of 20 Gy compared with 6.7 x 10(4) g-1 in controls (P less than 0.01). These results are consistent with most published data for mouse tumours though not for many human tumours.