Accelerated radiotherapy, carbogen and nicotinamide (ARCON) in locally advanced head and neck cancer: a feasibility study

Clinical trials targeting hypoxia

The concept of tumour hypoxia as a cause of radiation resistance has been prevalent for over 100 years. During this time, our understanding of tumour hypoxia has matured with the recognition that oxygen tension within a tumour is influenced by both diffusion and perfusion mechanisms. In parallel, clinical strategies to modify tumour hypoxia with the expectation that this will improve response to radiation have been developed and tested in clinical trials. Despite many disappointments, meta-analysis of the data on hypoxia modification confirms a significant impact on both tumour control and survival. Early trials evaluated hyperbaric oxygen followed by a generation of studies testing oxygen mimetics such as misonidazole, pimonidazole and etanidazole. One highly significant result stands out from the use of nimorazole in advanced laryngeal cancer with a significant advantage seen for locoregional control using this radiosensitiser. More recent studies have evaluated carbogen and nicotinamide targeting both diffusion related and perfusion related hypoxia. A significant survival advantage is seen in muscle invasive bladder cancer and also for locoregional control in hypopharygeal cancer associated with a low haemoglobin. New developments include the recognition that mitochondrial complex inhibitors reducing tumour oxygen consumption are potential radiosensitising agents and atovaquone is currently in clinical trials. One shortcoming of past hypoxia modifying trials is the failure to identify oxygenation status and select those patient with significant hypoxia. A range of biomarkers are now available including histological necrosis, immunohistochemical intrinsic markers such as CAIX and Glut 1 and hypoxia gene signatures which have been shown to predict outcome and will inform the next generation of hypoxia modifying clinical trials.

Temporal variation in the response of tumors to hyperoxia with breathing carbogen and oxygen

The effect of hyperoxygenation with carbogen (95% O₂ + 5% CO₂) and 100% oxygen inhalation on partial pressure of oxygen (pO₂) of radiation-induced fibrosarcoma (RIF-1) tumor was investigated. RIF-1 tumors were innoculated in C3H mice, and aggregates of oximetry probe, lithium phthalocyanine (LiPc), was implanted in each tumor. A baseline tumor pO₂ was measured by electron paramagnetic resonance (EPR) oximetry for 20 minutes in anesthetized mice breathing 30% O₂ and then the gas was switched to carbogen or 100 % oxygen for 60 minutes. These experiments were repeated for 10 days. RIF-1 tumors were hypoxic with a baseline tissue pO₂ of 6.2–8.3 mmHg in mice breathing 30% O₂. Carbogen and 100% oxygen significantly increased tumor pO₂ on days 1 to 5, with a maximal increase at approximately 32–45 minutes on each day. However, the extent of increase in pO₂ from the baseline declined significantly on day 5 and day 10. The results provide quantitative information on the effect of hyperoxic gas inhalation on tumor pO₂ over the course of 10 days. EPR oximetry can be effectively used to repeatedly monitor tumor pO₂ and test hyperoxic methods for potential clinical applications.

Dose prescription and optimisation based on tumour hypoxia

INTRODUCTION. Tumour hypoxia is an important factor that confers radioresistance to the affected cells and could thus decrease the tumour response to radiotherapy. The development of advanced imaging methods that quantify both the extent and the spatial distribution of the hypoxic regions has created the premises to devise therapies that target the hypoxic regions in the tumour. MATERIALS AND METHODS. The present study proposes an original method to prescribe objectively dose distributions that focus the radiation dose to the radioresistant tumour regions and could therefore spare adjacent normal tissues. The effectiveness of the method was tested for clinically relevant simulations of tumour hypoxia that take into consideration dynamics and heterogeneity of oxygenation. RESULTS AND DISCUSSION. The results have shown that highly heterogeneous dose distributions may lead to significant improvements of the outcome only for static oxygenations. In contrast, the proposed method that involves the segmentation of the dose distributions and the optimisation of the dose prescribed to each segment to account for local heterogeneity may lead to significantly improved local control for clinically-relevant patterns of oxygenation. The clinical applicability of the method is warranted by its relatively easy adaptation to functional imaging of tumour hypoxia obtained with markers with known uptake properties.

Accelerated radiotherapy, carbogen, and nicotinamide (ARCON) in the treatment of advanced bladder cancer: mature results of a Phase II nonrandomized study

PURPOSE

We previously showed that accelerated radiotherapy combined with carbogen and nicotinamide (ARCON) was an effective approach to use in the radical treatment of patients with advanced bladder carcinoma. Interim analysis from this Phase II study showed that it achieved a high level of locoregional control and overall survival (OS) and an acceptable level of adverse events.

METHODS AND MATERIALS

From 1994 to 2000, a total of 105 consecutive patients with high-grade superficial or muscle-invasive bladder carcinoma were given accelerated radiotherapy (50-55 Gy in 4 weeks) with carbogen alone or ARCON. End points of the study were OS, disease-specific, and local regional relapse-free survival, and for late adverse events, urinary (altered urination frequency, incontinence, hematuria, and urgency) and bowel dysfunction (stool frequency and blood loss).

RESULTS

At 5 and 10 years, local regional relapse-free survival rates were 44% after ARCON excluding the effect of salvage treatment and 62% after ARCON including the effect of salvage treatment (p = 0.04). Five- and 10-year rates were 35% and 27% for OS and 47% and 46% for disease-specific survival. The highest actuarial rate for Grade 3 or worse late urinary or bowel dysfunction was observed for altered urinary frequency (44% of patients had urinary events every 1 hour or less) and stool frequency of four or more events (26% at 5 years).

CONCLUSIONS

Historic comparisons with other studies indicate no evidence of an increase in severe or worse adverse events and good permanent control of bladder disease after ARCON radiotherapy.

Chemical radiosensitizers for use in radiotherapy

Radiosensitizers are intended to enhance tumour cell killing while having much less effect on normal tissues. Some drugs target different physiological characteristics of the tumour, particularly hypoxia associated with radioresistance. Oxygen is the definitive hypoxic cell radiosensitizer, the large differential radiosensitivity of oxic vs hypoxic cells being an attractive factor. The combination of nicotinamide to reduce acute hypoxia with normobaric carbogen breathing is showing clinical promise. 'Electron-affinic' chemicals that react with DNA free radicals have the potential for universal activity to combat hypoxia-associated radioresistance; a nitroimidazole, nimorazole, is clinically effective at tolerable doses. Hypoxia-specific cytotoxins, such as tirapazamine, are valuable adjuncts to radiotherapy. Nitric oxide is a potent hypoxic cell radiosensitizer; variations in endogenous levels might have prognostic significance, and routes to deliver nitric oxide specifically to tumours are being developed. In principle, many drugs can be delivered selectively to hypoxic tumours using either reductase enzymes or radiation-produced free radicals to activate drug release from electron-affinic prodrugs. A redox-active agent based on a gadolinium chelate is being evaluated clinically. Pyrimidines substituted with bromine or iodine are incorporated into DNA and enhance free radical damage; fluoropyrimidines act by different mechanisms. A wide variety of drugs that influence the nature or repair of DNA damage are being evaluated in conjunction with radiation; it is often difficult to define the mechanisms underlying chemoradiation regimens. Drugs being evaluated include topoisomerase inhibitors (e.g. camptothecin, topotecan), and the hypoxia-activated anthraquinone AQ4N; alkylating agents include temozolomide. Drugs involved in DNA repair pathways being investigated include the potent poly(ADP ribose)polymerase inhibitor, AG14,361. Proteins involved in cell signalling, such as the Ras family, are attractive targets linked to radioresistance, as are epidermal growth factor receptors and linked kinases (drugs including vandetanib [ZD6,474], cetuximab and gefitinib), and cyclooxygenase-2 (celecoxib). The suppression of radioprotective thiols seems to offer more potential with alkylating agents than with radiotherapy, although it remains a strategy worthy of exploration.

Endogenous markers of two separate hypoxia response pathways (hypoxia inducible factor 2 alpha and carbonic anhydrase 9) are associated with radiotherapy failure in head and neck cancer patients recruited in the CHART randomized trial

PURPOSE

Randomized controlled trials have generally shown a benefit from accelerated radiotherapy in head and neck squamous cell carcinoma (HNSCC). However, the large randomized United Kingdom trial CHART (Continuous Hyperfractionated Accelerated Radiotherapy) failed to show a benefit of strongly accelerated over standard radiotherapy (RT) in 918 patients with HNSCC. In this study, we investigated the impact of tumor hypoxia on the outcome of HNSCC patients in the CHART trial. There are two distinct hypoxia inducible factors (HIFs) that control different gene response pathways and we assessed them both with endogenous markers of hypoxia, hypoxia inducible factor HIF-2 alpha (HIF-2) and carbonic anhydrase CA9, an indicator of HIF-1 alpha (HIF-1) function.

METHODS

Tissue from pre-RT biopsies performed in 198 of 918 patients recruited was analyzed for the immunohistochemical expression of HIF-2 and CA9.

RESULTS

A significant association of high HIF2 and of high CA9 reactivity with poor locoregional control (P < .0001 and P = .0002, respectively) and poor survival (P = .0004 and 0.002, respectively) was noted. In multivariate analysis, HIF-2 and CA9 maintained their independent prognostic significance. Coexpression of both pathways had an additive effect, supporting their independent role. The uni-directional hypothesis, that a benefit from randomization to CHART should be seen in the nonhypoxic tumors, was supported by the data (one-tailed P = .04).

CONCLUSION

Expression of endogenous markers of hypoxia for the HIF-1 and HIF-2 pathway is strongly associated with radiotherapy failure. Using immunohistochemical methods it is possible to identify subgroups of HNSCC patients who are highly curable with radiotherapy, or who are excellent candidates for clinical trials on hypoxia-targeting drugs in two distinct pathways.

Acute and late morbidity in the treatment of advanced bladder carcinoma with accelerated radiotherapy, carbogen, and nicotinamide

BACKGROUND

Accelerated radiotherapy combined with carbogen and nicotinamide (ARCON) to overcome tumor hypoxia and cell proliferation achieved high tumor control and survival in Phase II studies of patients with advanced head and neck and bladder carcinomas. Thus, morbidity and treatment outcomes from the latter study were analyzed to evaluate the therapeutic potential of ARCON.

METHODS

Acute and late morbidity was assessed in 105 patients with high-grade superficial or muscle-invasive bladder carcinoma who were given accelerated radiotherapy (50-55 grays in 4 weeks) with carbogen alone or with ARCON. Urinary dysfunction was scored based on daytime frequency, nocturia, incontinence, dysuria, hematuria, and urgency. Bowel morbidity was based on stool frequency and consistency, rectal discharge, blood loss, and medication. Endpoints for treatment outcome were overall survival, disease-free survival, and locoregional control.

RESULTS

Nearly all patients experienced reduced ability to retain urine beyond 2 hours, although 20-30% had almost normal function at night. Incidence of acute moderate or worse dysuria was 41% with ARCON and 56% with carbogen; 96% and 76% of patients, respectively, had bowel frequencies > or = 3 times per day. By 10-12 weeks from the start of radiotherapy, acute reactions returned to baseline levels. At 3 years, the daytime frequency < or = 2 times per hour was approximately 75% in both arms. Incidence of severe hematuria (< or = 25%) and urinary urgency (< or = 16%) was much lower. No more than 6% of patients had severe bowel morbidity. With most assays, the differences between schedules were not significant either for acute or late morbidity. Local tumor control and survival rates at 3 years were 53% and 43%, respectively, for ARCON, similar to the rates for carbogen alone.

CONCLUSIONS

Historical comparisons suggested no overt increase in normal tissue radiosensitivity when adding carbogen and nicotinamide. Although, for some endpoints, the incidence of late sequelae was higher than expected, overall morbidity was no worse than reported by others. The data indicated that ARCON could achieve a therapeutic gain in patients with advanced bladder carcinoma. A Phase III, randomized, multicenter trial is underway currently in the United Kingdom to evaluate these findings.

Radiotherapy alone or combined with carbogen breathing for squamous cell carcinoma of the head and neck

BACKGROUND

The current study was performed to investigate the efficacy of carbogen (95% oxygen [O(2)] and 5% carbon dioxide [CO(2)]) breathing during definitive radiotherapy (RT) to enhance local control.

METHODS

Between November 1996 and November 2002, 101 patients with previously untreated T2 to T4 squamous cell carcinomas of the oropharynx, larynx, and hypopharynx were entered onto a prospective trial and randomized to receive definitive hyperfractionated RT alone or combined with carbogen breathing. Patients were stratified according to T classification and primary tumor site. Follow-up ranged from 1-91 months (median, 38 months). All living patients had follow-up for more than 2 years. Outcomes analyses were performed according to intent to treat.

RESULTS

Definitive RT alone was completed as planned in 50 of 51 patients (98%); 49 of the 50 patients (98%) who were randomized to receive carbogen breathing were able to complete the RT as planned. Three patients randomized to receive carbogen breathing declined carbogen. The 5-year outcomes after RT alone or combined with carbogen were as follows: local control, 83% versus 88% (P = 0.5155); locoregional control, 81% versus 83% (P = 0.7174); distant metastasis-free survival, 82% versus 86% (P = 0.5184); cause-specific survival, 73% versus 77% (P = 0.5866); and absolute survival, 53% versus 58% (P = 0.4856).

CONCLUSIONS

The addition of carbogen breathing to definitive RT did not appear to improve the likelihood of local control significantly. However, because of the limited size of the current study, the authors cannot definitively conclude that carbogen breathing is ineffective.

Report from the Radiation Oncology Committee of the Southwest Oncology Group (SWOG)

To achieve the ultimate goal of cancer treatment, which is 100% cancer control with negligible toxicity, the therapeutic window must be enlarged, allowing for higher doses of beneficial treatments with reduced toxicity. The advent of image- and metabolism-guided therapy offers the best opportunity to date for combining modern radiation targeting and imaging techniques. Indeed, for the first time, it is reasonable to locally target metastatic disease with the goal of sterilization. Combining these focal radiation techniques with novel targeted antiproliferative agents and full-dose classic cytotoxic chemotherapy will become more effective as we learn to use these compounds in a less systemically toxic manner and as radiation fields become more defined. In addition, increasing numbers of biologic modifiers of normal tissue response are becoming available, and they suggest great promise for decreasing the normal tissue toxicity resulting from both radiation and chemotherapy treatments. Thus, radiation metastectomy for gross metastases, used together with systemic control of micrometastatic disease, may yield improved survival rates. This hypothesis is ready for testing in cancers of the breast, prostate, colon, and in sarcomas. Enlarging the therapeutic window is a major goal that would allow for an increasingly favorable therapeutic gain.

Dynamic response of breast tumor oxygenation to hyperoxic respiratory challenge monitored with three oxygen-sensitive parameters

The simultaneous measurement of three oxygen-sensitive parameters [arterial hemoglobin oxygen saturation (SaO2), tumor vascular-oxygenated hemoglobin concentration ([HbO2]), and tumor oxygen tension (pO2)] in response to hyperoxic respiratory challenge is demonstrated in rat breast tumors. The effects of two hyperoxic gases [oxygen and carbogen (5% CO2 and 95% O2)] were compared, by use of two groups of Fisher rats with subcutaneous 13762NF breast tumors implanted in pedicles on the foreback. Two different gas-inhalation sequences were compared, i.e., air-carbogen-air-oxygen-air and air-oxygen-air-carbogen-air. The results demonstrate that both of the inhaled, hyperoxic gases significantly improved the tumor oxygen status. All three parameters displayed similar dynamic response to hyperoxic gas interventions, but with different response times: the fastest for arterial SaO2, followed by biphasic changes in tumor vascular [HbO2], and then delayed responses for pO2. Both of the gases induced similar changes in vascular oxygenation and regional tissue pO2 in the rat tumors, and changes in [HbO2] and mean pO2 showed a linear correlation with large standard deviations, which presumably results from global versus local measurements. Indeed, the pO2 data revealed hetergeneous regional response to hyperoxic interventions. Although preliminary near-infrared measurements had been demonstrated previously in this model, the addition of the pO2 optical fiber probes provides a link between the noninvasive relative measurements of vascular phenomena based on endogenous reporter molecules, with the quantitative, albeit, invasive pO2 determinations.

Radiotherapy and chemotherapy with or without carbogen and nicotinamide in inoperable biopsy-proven glioblastoma multiforme

BACKGROUND

Nicotinamide and carbogen have been shown to enhance the radiation effect in tumour models.

PURPOSE

Prospective evaluation of the toxicity and efficacy of carbogen and nicotinamide with external beam radiotherapy in the management of inoperable glioblastoma.

PATIENTS AND METHODS

From April 1995 to December 1997, 33 patients with inoperable biopsy-proven glioblastoma multiforme (GBM) were enrolled in a phase II trial, to undergo radiotherapy (59.4 Gy in 1.8 Gy/fraction), intra-arterial cerebral chemotherapy (ACNU 100 mg/m(2), three cycles), carbogen breathing (15 l/min), and nicotinamide (85 mg/kg). This experimental group was compared to a control group of 38 patients with inoperable GBM treated with radiotherapy and three cycles of nitrosourea-based chemotherapy from January 1990 to March 1995, in our institution.

RESULTS

In the experimental group, carbogen breathing was well tolerated, but only 51.5% of patients completed daily nicotinamide over the 6.5-week treatment period. Nausea and vomiting were the most frequent side effects of nicotinamide. No significant difference in overall survival was observed among the two treatment groups: median survival times were 36.7 and 35.3 weeks for patients treated with carbogen and nicotinamide, and for those treated in the control group, respectively.

CONCLUSION

The association of carbogen and nicotinamide with radiotherapy is feasible, but tolerable only in 51.5% of patients with GBM. Carbogen and nicotinamide did not appear to modify the evolution of glioblastoma.

ARCON: a novel biology-based approach in radiotherapy

Two mechanisms of radiotherapy resistance which are of major importance in various tumour types are tumour-cell repopulation and hypoxia. ARCON (accelerated radiotherapy with carbogen and nicotinamide) is a new therapeutic strategy that combines radiation treatment modifications, with the aim of counteracting these resistance mechanisms. To limit clonogenic repopulation during therapy, the overall duration of the radiotherapy is reduced, generally by delivering several fractions per day. This accelerated radiotherapy is combined with inhalation of hyperoxic gas to decrease diffusion-limited hypoxia, and nicotinamide, a vasoactive agent, to decrease perfusion-limited hypoxia. Preclinical studies have been done to test the enhancing effects of these three components of ARCON, individually and in combination, in several experimentally induced tumours and normal tissues. In a mouse mammary carcinoma, the tumour-control rate obtained with ARCON was the same as that with conventional treatment, but with a radiation dose almost 50% lower. Phase 1 and 2 clinical trials have shown the feasibility and tolerability of ARCON, and have produced promising results in terms of tumour control. In particular in cancers of the head and neck and bladder, the local tumour-control rates are higher than in other studies, and phase 3 trials for these tumour types are underway. In conjunction with these trials, hypoxia markers detectable by immunohistochemistry are being tested for their potential use in predictive assays to select patients for ARCON and other hypoxia-modifying therapies.

Accelerated radiation therapy, seven fractions per week, for advanced head and neck cancer--a feasibility study

AIM

The feasibility and improved efficacy of six conventional fractions per week has previously been proven in a Danish randomized trial. We tested the tolerance and efficacy of seven conventional fractions per week using a concomitant boost technique.

METHODS

From September 1996 to May 1998, 20 patients with squamous cancer of the head and neck were treated with radiation alone. The site of disease was oropharynx in 35%, larynx in 30%, oral cavity 20%, and hypopharynx in 15%. All patients had stage III (10%)/IV (90%) disease. The planned total dose to gross disease was 66 Gy delivered in 33 fractions of 2 Gy each in 31 days. Large volumes were treated to 46 Gy, 2 Gy per fraction, once each morning, Monday-Friday. Boosts to gross disease consisted of 20 Gy in 10 fractions > or = 6 h after the morning dose on Tuesday and Thursday.

RESULTS

Acute toxicity > or = grade 3 was mucous membrane 75%, pharynx 60%, skin 65%, and larynx 35%. One acute toxicity was fatal. Chronic toxicity > or = grade 3 (three patients) was mucous membrane 5%, pharynx 10%, skin 5%, salivary 15%, and larynx 5%. All patients with grade III or greater late toxicity had grade III acute toxicity in each toxicity category. At 30 months Kaplan-Meier survival is 55%, and local control is 39%.

CONCLUSIONS

Without increasing resource utilization this scheme accelerates treatment by 30%. As expected acute toxicity is high but manageable. Chronic toxicity appears comparable to other altered fractionation strategies however the median follow up is only 30 months more toxicity may emerge as the data matures. We plan further trials using 1.8 Gy fractions to reduce toxicity.

ARCON: experience in 215 patients with advanced head-and-neck cancer

PURPOSE

"ARCON" combines accelerated radiotherapy to counteract tumor repopulation with carbogen breathing and nicotinamide to reduce chronic and acute hypoxia. The aim of this Phase II study was to assess the feasibility, toxicity, and potential effectiveness of ARCON for advanced head-and-neck cancer.

METHODS AND MATERIALS

The study included 215 patients with head-and-neck carcinoma distributed as follows: larynx, n = 100; hypopharynx, n = 50; oropharynx, n = 52; oral cavity, n = 13; Stage II, n = 8, Stage III, n = 71, and Stage IV, n = 136. Accelerated radiotherapy was given to a total dose of 64-68 Gy in 2-Gy fractions within 36-38 days. This was combined with carbogen breathing during irradiation and administration of nicotinamide (60-80 mg/kg) 1-1.5 h before irradiation.

RESULTS

There was full compliance with carbogen breathing in 88% of the patients. A nicotinamide dose of 80 mg/kg produced severe nausea and vomiting, necessitating discontinuation of the drug, in 31% of the patients. Adjustment of the dose to 60 mg/kg and antiemesis prophylaxis reduced the discontinuation rate to 10%. Confluent mucositis was observed in 91% of the patients with a median duration of 6 weeks. Grade 4 late complications occurred in 5% of the patients. The actuarial 3-year local control rates were 80% for larynx, 69% for hypopharynx, 88% for oropharynx, and 37% for oral cavity tumors. For T3-4 tumors, the local control rates were 80% for larynx, 60% for hypopharynx, 87% for oropharynx, and 29% for oral cavity. Regional control rates were 100% for N0, 93% for N1, and 74% for N2 disease.

CONCLUSION

ARCON yields high local and regional control rates in advanced head-and-neck carcinomas, and compliance is satisfactory and morbidity acceptable. The local control rate of 80% for T3 and T4 larynx carcinomas offers excellent possibilities for organ preservation.

Dynamics of tumor oxygenation and red blood cell flux in response to inspiratory hyperoxia combined with different levels of inspiratory hypercapnia

BACKGROUND AND PURPOSE

Increasing arterial oxygen partial pressure (pO2) by breathing hyperoxic gases is an effective means of improving tumor oxygenation, although the efficacy of adding CO2 to the inspiratory gas has been discussed controversially. This study aimed at analyzing the impact of different inspiratory CO2 fractions on the time course of oxygenation and perfusion changes in experimental tumors during and after inspiratory hyperoxia.

MATERIAL AND METHODS

Perfusion and oxygenation of rat DS-sarcomas were studied during spontaneous breathing of pure oxygen or hyperoxic gas mixtures containing different CO2 fractions (1, 2.5 or 5%). Red blood cell (RBC) flux was assessed as a measure of tumor perfusion using the laser Doppler technique and temporal changes in mean tumor pO2 were measured polarographically.

RESULTS

Mean tumor pO2 increased 3.6-fold with pure oxygen, approx. 3.3-fold when 1 or 2.5% CO2 was added and 2.7-fold during carbogen breathing. RBC flux also increased by 25-30% with all gases. With pure oxygen and with 1% CO2 (+99% O2), perfusion changes paralleled those of the mean arterial blood pressure whereas with higher CO2 fractions, a decrease in resistance to flow was observed. The differences found with the various gas mixtures were more pronounced after the end of hyperoxia. With pure oxygen, perfusion immediately returned to pretreatment values whereas with higher CO2 fractions perfusion remained elevated for at least 30 min.

CONCLUSIONS

Higher inspiratory CO2 fractions (2.5 or 5%) lead to a prolonged improvement of tumor perfusion after the end of inspiratory hyperoxia when compared with pure oxygen breathing. Since no principal differences in oxygenation and perfusion were seen between the gases containing 2.5 and 5% CO2, the former may be preferable for inspiratory hyperoxia.

Simultaneous administration of glucose and hyperoxic gas achieves greater improvement in tumor oxygenation than hyperoxic gas alone

PURPOSE

To test the feasibility of hyperglycemic reduction of oxygen consumption combined with oxygen breathing (O(2)), to improve tumor oxygenation.

METHODS AND MATERIALS

Fischer-344 rats bearing 1 cm R3230Ac flank tumors were anesthetized with Nembutal. Mean arterial pressure, heart rate, tumor blood flow ([TBF], laser Doppler flowmetry), pH, and pO(2) were measured before, during, and after glucose (1 or 4 g/kg) and/or O(2).

RESULTS

Mean arterial pressure and heart rate were unaffected by treatment. Glucose at 1 g/kg yielded maximum blood glucose of 400 mg/dL, no change in TBF, reduced tumor pH (0.17 unit), and 3 mm Hg pO(2) rise. Glucose at 4 g/kg yielded maximum blood glucose of 900 mg/dL, pH drop of 0.6 unit, no pO(2) change, and reduced TBF (31%). Oxygen tension increased by 5 mm Hg with O(2). Glucose (1 g/Kg) + O(2) yielded the largest change in pO(2) (27 mm Hg); this is highly significant relative to baseline or either treatment alone. The effect was positively correlated with baseline pO(2), but 6 of 7 experiments with baseline pO(2) < 10 mm Hg rose above 10 mm Hg after combined treatment.

CONCLUSION

We demonstrated the feasibility of combining hyperglycemia with O(2) to improve tumor oxygenation. However, some cell lines are not susceptible to the Crabtree effect, and the magnitude is dependent on baseline pO(2). Additional or alternative manipulations may be necessary to achieve more uniform improvement in pO(2).

Blood hemoglobin level may affect radiosensitivity-preliminary results on acutely reacting normal tissues

PURPOSE

To evaluate the influence of blood hemoglobin concentration on the radiosensitivity of acutely reacting normal tissues.

METHODS AND MATERIALS

Weekly scores (EORTC/RTOG criteria) for acute reactions of skin and mucosa are available for 60 patients with cancer of the head and neck undergoing a standard conventional radiotherapy. The prognostic significance of blood hemoglobin levels on the development of acute reactions is studied by multivariate analysis (Cox Proportional Hazards Model). Further, the incidence and the time to development of these reactions is looked at in cohorts of patients with different mean blood hemoglobin concentrations during radiotherapy. Patients are therefore classified into a "severely anemic group" (hemoglobin < 11.0 g/100 mL), and into a cohort with a blood hemoglobin value equal or above 11.0 g/100 mL.

RESULTS

Normal tissue scoring and monitoring of blood hemoglobin levels allows for a detailed analysis of possible correlations. A decrease in the mean blood hemoglobin value of 1 g/100 mL predicts a reduced risk to develop a skin reaction of Grade 2 or 3 (RR = 0.9; p = 0.08; RR = 0.8; p = 0.26, respectively) or a mucosa reaction of Grade 3 (RR = 0.8; p = 0.16), independent from the radiation dose, the treatment time and from previous surgery within the radiation volume (multivariate analysis). Likewise, patients with severe anemia develop grade 3 mucositis or dermatitis less often (0%; 13%) as compared to those with blood hemoglobin concentrations equal or above 11.0 g/100 mL (21%; 19%). Skin and mucosa reactions further tend to occur later in the course of radiation. The observations are not statistically significant and possible reasons will be discussed.

CONCLUSIONS

A decreased blood hemoglobin concentration may-perhaps by an impaired tissue oxygenation-reduce the radiosensitivity of normal tissue such as skin and mucosa. However, the data is preliminary and needs further confirmation.

The effect of nicotinamide on spontaneous and induced activity in smooth and skeletal muscle

BACKGROUND AND PURPOSE

Nicotinamide (NA) is currently undergoing clinical trials as a tumour radiosensitizer. The dose that can be administered is currently 80 mg/kg per day, but this may be restricted to 60 mg/kg per day by the high incidence of nausea and vomiting. To investigate some of NA's underlying mechanisms of action, we have used an ex vivo system to study the direct effect of this drug, over a wide range of concentrations, on isolated spontaneously active rat ileum. Effects on the gut were compared with the action of NA on skeletal and vascular smooth muscle.

MATERIALS AND METHODS

Isolated rat ileum rings were perfused with oxygenated Krebs' solution in an organ bath. NA (1 microM to 10 mM) was introduced to the perfusate and the change in amplitude of spontaneous peristaltic activity recorded. Dissected frog sartorius muscle was bathed in modified oxygenated Ringer's solution in an organ bath. The muscle was electrically stimulated to generate isometric contractions. Tension was then measured before and after the addition of a range of NA concentrations (8.2-24.6 mM) to the organ bath.

RESULTS

NA inhibited peristalsis in the ileum in a dose-dependent manner. At a drug concentration of 1 mM the amplitude of contractions was reduced to <50% of the initial control value. NA had no effect on the electrically induced contractions in the isolated frog sartorius muscle.

CONCLUSIONS

Gut smooth muscle is highly sensitive to the relaxant effect of NA producing 50% relaxation at a concentration approximately 10 fold lower than that required in rat arterial smooth muscle, while having no effect on non-mammalian skeletal smooth muscle. This may provide explanations for the occurrence of emesis in patients undergoing combined nicotinamide therapies and highlight possible alternatives available to counter this unwanted side-effect.

Psychometric testing of fatigue instruments for use with cancer patients

BACKGROUND

Cancer treatment-related fatigue (CRF) is a common side effect of cancer treatment. A problem identified in most reviews of CRF is lack of sound approaches to measurement that are congruent with the conceptualization of CRF as a self-perceived state. The diversity of instruments available to measure fatigue and the lack of comprehensive testing of several promising instruments with cancer patients undergoing treatment provided the rationale for this study. The purpose of this article is to report the results of psychometric testing of several fatigue instruments in patients undergoing cancer treatment.

OBJECTIVES

The aims of this study were to determine the reliability, validity, and responsiveness of each instrument and to determine the ability of each instrument to capture CRF.

METHODS

Existing fatigue instruments with published psychometric information that indicated suitability for further testing were selected and included the Profile of Mood States Short Form fatigue subscale (F_POMS-sf), Multidimensional Assessment of Fatigue (MAF), Lee Fatigue Scale (LFS), and the Multidimensional Fatigue Inventory (MFI). Data were collected at a university-based clinical cancer center and a freestanding comprehensive cancer center. Subjects completed all study instruments, which were presented in random order, at a time when CRF was expected to be high and again when it was expected to be low. A subset of subjects completed the instruments within 48 hours of one of the data collection points when CRF was expected to be relatively unchanged to provide stability data.

RESULTS

Reliability estimates using Cronbach's alpha indicated that all instruments examined had good internal consistency. Test-retest correlations showed good stability for total scores on all the instruments, but some subscales of the LFS and MFI had marginal stability. Factor analysis of all instruments indicated that only the LFS and the F_POMS-sf fully supported their construct validity. All of the instruments showed responsiveness to changes in CRF related to treatment.

CONCLUSIONS

The results of the study provide researchers and clinicians with detailed comparisons of the performance of established fatigue measures in cancer patients undergoing treatment to use when selecting measures of CRF.

Nicotinamide (vitamin B3) as an effective antioxidant against oxidative damage in rat brain mitochondria

Nicotinamide (vitamin B3) an endogenous metabolite, showed significant inhibition of oxidative damage induced by reactive oxygen species (ROS) generated by ascorbate-Fe2+ and photosensitization systems in rat brain mitochondria. It protected against both protein oxidation and lipid peroxidation, at millimolar concentrations. Inhibition was more pronounced against oxidation of proteins than peroxidation of lipids. Chemically related endogenous compounds, tryptophan and isonicotinic acid, showed comparable inhibitory properties. The protective effect observed, at biologically relevant concentrations, with nicotinamide was more than that of the endogenous antioxidants ascorbic acid and alpha-tocopherol. Hence our studies suggest that nicotinamide (vitamin B3) can be considered as a potent antioxidant capable of protecting the cellular membranes in brain, which is highly susceptible to prooxidants, against oxidative damage induced by ROS.

Contractile properties of human renal cell carcinoma recruited arteries and their response to nicotinamide

BACKGROUND AND PURPOSE

The manipulation of tumour blood supply and thus oxygenation is a potentially important strategy for improving the treatment of solid tumours by radiation. Increased knowledge about the characteristics that distinguish the tumour vasculature from its normal counterparts may enable tumour blood flow to be more selectively modified. Nicotinamide (NA) causes relaxation of preconstricted normal and tumour-supply arteries in rats. It has also been shown to affect microregional blood flow in human tumours. Direct effects of NA on human tumour supply arteries have not previously been reported. This paper describes our evaluation of the effects of NA on two parameters: 'spontaneous', oscillatory contractile activity and agonist (phenylephrine)-induced constriction in the arteries supplying human renal cell carcinomas.

MATERIALS AND METHODS

Isolated renal cell carcinoma feeder vessels were perfused in an organ bath with the alpha(1)-adrenoceptor agonist phenylephrine (PE). When the arteries had reached a plateau of constriction, nicotinamide (8.2 mM) was added to the perfusate and changes in perfusion pressure were measured.

RESULTS

PE (10 microM) induced a sustained constriction in the majority of the renal cell carcinoma feeder vessels examined, demonstrating that they retain contractile characteristics, at least in response to this alpha(1)-adrenoceptor agonist. In combination with NA (8.2 mM) the constriction was significantly attenuated in half of the preparations. In addition, seven arteries exhibited spontaneous contractile activity which was significantly attenuated by NA in six of them.

CONCLUSIONS

NA can significantly attenuate both 'spontaneous' and agonist-induced constrictions in tumour-recruited human arteries, though not all arteries are sensitive.

Carcinoma of the cervix and the use of hyperbaric oxygen with radiotherapy: a report of a randomised controlled trial

BACKGROUND AND PURPOSE

A randomised controlled trial of hyperbaric oxygen in the radiotherapy of Stage IIb and III carcinoma of cervix was performed between 1971 and 1980. Apart from an abstract giving an interim report in 1977, results have not been published.

MATERIAL AND METHODS

In a four arm study, 335 patients were randomised to treatment in 10 or 28 fractions, in hyperbaric oxygen or in air. Data is available concerning 327 cases and this has been analysed.

RESULTS

There was no advantage in tumour control shown with the use of hyperbaric oxygen. There was evidence for an increase in late radiation morbidity when treatment was given in hyperbaric oxygen rather than in air and when, using 10 fractions, a total dose of 45 rather than 40 Gy was achieved. For late intestinal morbidity, the fractionation sensitivity (alpha/beta ratio) was calculated to be 4.3 Gy and the steepness of the dose response curve (gamma50) to be 2.6.

CONCLUSIONS

Hyperbaric oxygen gave no benefit in the treatment of patients with stage IIb and III carcinoma of the cervix treated with radiotherapy using two fractionation regimes. Important data regarding late radiation morbidity has been revealed.

The effect of combined nicotinamide and carbogen treatments in human tumour xenografts: oxygenation and tumour control studies

BACKGROUND AND PURPOSE

This was an investigation to study the effect of giving carbogen and nicotinamide (CON) on pO2 and the radiation response of human xenografted tumours.

MATERIALS AND METHODS

The human xenografts were two sarcomas (ENE2 and ES3) and a glioblastoma (HTZ17). Nicotinamide (500 mg/ kg, i.p.) was administered 60 min before PO2 measurements and irradiation, while carbogen was given for 5 min before and during these treatments. Tumour pO2 was measured with an Eppendorf electrode and radiation response was assessed by local tumour control following irradiation with 10 daily fractions.

RESULTS

All three xenografts were found to be poorly oxygenated (about 80% of all pO2 values were < or =2.5 mmHg). CON treatment improved the oxygenation status in all three tumours such that 65, 52 and 71% of the pO2 values were < or =2.5 mmHg in ENE2, ES3 and HTZ17, respectively. However, only in ES3 was this decrease significant. The TCD50 doses for all tumours were around 52-54 Gy. No significant improvement was seen with CON in ENE2 (TCD50 = 48 Gy) and HTZ17 (TCD50 = 56 Gy), but for the ES3 xenograft a significant decrease to 42 Gy was found.

CONCLUSIONS

The three tumours used in this study appeared to show the same level of hypoxia as measured both by pO2 and radiation response. However, only one tumour showed a significant improvement after CON treatment, suggesting that not all hypoxic human tumours might benefit from this type of therapy.

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.