Changes in tumor oxygenation during combined treatment with split-course radiotherapy and chemotherapy in patients with head and neck cancer

Hypo-fractionated radiotherapy with concurrent chemotherapy for locoregional recurrence of non-small cell lung cancer after complete resection: A prospective, single-arm, phase II study (GASTO-1017)

OBJECTIVES

To explore the efficacy and toxicities of split-course hypo-fractionated radiotherapy with concurrent chemotherapy (HFRT-CHT) with intensity modulated radiotherapy (IMRT) technique in non-small cell lung cancer (NSCLC) patients with postoperative locoregional recurrence (LRR).

MATERIALS AND METHODS

NSCLC patients were eligible if confirmed as LRR disease without distant metastasis after complete resection. HFRT-CHT using IMRT technique was administered with 51 Gy in 17 fractions or 40 Gy in 10 fractions as the first course followed by a break. Patients with no disease progression and no persistent Grade ≥2 toxicities had the second course of 15 Gy in 5 fractions or 28 Gy in 7 fractions as a boost. The primary endpoint was progression-free survival (PFS).

RESULTS

Fifty-eight patients were enrolled and analyzed. With a median follow-up of 23.9 months for all, the 2-year and 3-year PFS rate was 59.7 % and 46.4 %, the 2-year and 3-year OS rate was 72.5 % and 52.2 %, respectively, and a favorable objective response rate of 95.9 % was obtained after the whole courses protocol. Grade 3 acute pneumonitis and esophagitis occurred in 2 (3.4 %) and 7 (12.1 %) patients, and fatal pneumonitis was reported in one case (1.7 %). Exploratory subgroup analysis showed that performance status (PS) (PS 0 vs. 1: 2-year PFS, 88.1 % vs. 46.9 %,P = 0.001; 2-year OS, 100 % vs. 59.4 %, P < 0.001), recurrence site (single vs. multiple: 2-year PFS, 93.8 % vs. 47.4 %, P = 0.008; 2-year OS, 100 % vs. 63.0 %, P = 0.001), and gross tumor volume (GTV) (<50cm³ vs. ≥ 50cm³: 2-year PFS, 70.6 % vs. 46.2 %, P = 0.024; 2-year OS, 85.6 % vs. 57.4 %, P = 0.034) were significantly associated with PFS and OS.

CONCLUSION

Split-course HFRT-CHT with IMRT technique achieved promising disease control and satisfactory survival with moderate toxicities in postoperative LRR of NSCLC. Good PS, a single recurrence site and GTV<50cm³ tended to have prolonged PFS and OS. Early detection of LRR may improve the efficacy of HFRT-CHT.

Evolution of the hypoxic compartment on sequential oxygen partial pressure maps during radiochemotherapy in advanced head and neck cancer

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Repeated PET imaging of hypoxia may be pivotal in radiotherapy outcome prediction.

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Oxygen partial pressure maps can be non-linearly derived from radiotracer uptake.

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The hypoxic target volume evolution in extension and severity can be determined.

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The first two treatment week parameters have potential for outcome prediction.

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Information may be used for treatment adaptation personalised strategies.

Background and purpose

Longitudinal Positron Emission Tomography (PET) with hypoxia-specific radiotracers allows monitoring the time evolution of regions of increased radioresistance and may become fundamental in determining the radiochemotherapy outcome in Head-and-Neck Squamous Cell Carcinoma (HNSCC). The aim of this study was to investigate the evolution of the hypoxic target volume on oxygen partial pressure maps (pO₂-HTV) derived from ¹⁸FMISO-PET images acquired before and during radiochemotherapy and to uncover correlations between extent and severity of hypoxia and treatment outcome.

Material and methods

¹⁸FMISO-PET/CT images were acquired at three time points (before treatment start, in weeks two and five) for twenty-eight HNSCC patients treated with radiochemotherapy. The images were converted into pO₂ maps and corresponding pO₂-HTVs (pO₂-HTV₁, pO₂-HTV₂, pO₂-HTV₃) were contoured at 10 mmHg. Different parameters describing the pO₂-HTV time evolution were considered, such as the percent and absolute difference between the pO₂-HTVs (%HTV_i,j and HTV_i-HTV_j with i,j = 1, 2, 3, respectively) and the slope of the linear regression curve fitting the pO₂-HTVs in time. Correlations were sought between the pO₂-HTV evolution parameters and loco-regional recurrence (LRR) using the Receiver Operating Characteristic method.

Results

The Area Under the Curve values for %HTV_1,2, HTV₁-HTV₂, HTV₁-HTV₃ and the slope of the pO₂-HTV linear regression curve were 0.75 (p = 0.04), 0.73 (p = 0.02), 0.73 (p = 0.02) and 0.75 (p = 0.007), respectively. Other parameter combinations were not statistically significant.

Conclusions

The pO₂-HTV evolution during radiochemotherapy showed predictive value for LRR. The changes in the tumour hypoxia during the first two treatment weeks may be used for adaptive personalized treatment approaches.

Spectroscopic investigation of radiation-induced reoxygenation in radiation-resistant tumors

Fractionated radiation therapy is believed to reoxygenate and subsequently radiosensitize surviving hypoxic cancer cells. Measuring tumor reoxygenation between radiation fractions could conceivably provide an early biomarker of treatment response. However, the relationship between tumor reoxygenation and local control is not well understood. We used noninvasive optical fiber-based diffuse reflectance spectroscopy to monitor radiation-induced changes in hemoglobin oxygen saturation (sO2) in tumor xenografts grown from two head and neck squamous cell carcinoma cell lines - UM-SCC-22B and UM-SCC-47. Tumors were treated with 4 doses of 2 Gy over 2 consecutive weeks and diffuse reflectance spectra were acquired every day during the 2-week period. There was a statistically significant increase in sO2 in the treatment-responsive UM-SCC-22B tumors immediately following radiation. This reoxygenation trend was due to an increase in oxygenated hemoglobin (HbO2) and disappeared over the next 48 h as sO2 returned to preradiation baseline values. Conversely, sO2 in the relatively radiation-resistant UM-SCC-47 tumors increased after every dose of radiation and was driven by a significant decrease in deoxygenated hemoglobin (dHb). Immunohistochemical analysis revealed significantly elevated expression of hypoxia-inducible factor (HIF-1) in the UM-SCC-47 tumors prior to radiation and up to 48 h postradiation compared with the UM-SCC-22B tumors. Our observation of a decrease in dHb, a corresponding increase in sO2, as well as greater HIF-1α expression only in UM-SCC-47 tumors strongly suggests that the reoxygenation within these tumors is due to a decrease in oxygen consumption in the cancer cells, which could potentially play a role in promoting radiation resistance.

Lymphocyte Infiltration Determines the Hypoxia-Dependent Response to Definitive Chemoradiation in Head-and-Neck Cancer: Results from a Prospective Imaging Trial

Tumor hypoxia in head-and-neck squamous cell carcinoma (HNSCC) leads to an immunosuppressive microenvironment and reduces the response to radiotherapy. In this prospective imaging trial, we investigated potential interactions between functional hypoxia imaging and infiltrating lymphocyte levels as a potential predictor for treatment response in HNSCC patients. Methods: In total, 49 patients receiving definitive chemoradiation for locally advanced HNSCCs underwent pretherapeutic biopsies and peritherapeutic hypoxia imaging using ¹⁸F-misonidazole PET at weeks 0, 2, and 5 during chemoradiation. Hematoxylin-eosin and immunohistochemical stainings for tumor-infiltrating lymphocytes, tissue-based hypoxia, and microvascular markers were analyzed and correlated with the longitudinal hypoxia dynamics and patient outcomes. Results: High levels of tumor-infiltrating total lymphocytes correlated with superior locoregional control (LRC) (hazard ratio [HR], 0.279; P = 0.011) and progression-free survival (PFS) (HR, 0.276; P = 0.006). Similarly, early resolution of ¹⁸F-misonidazole PET-detected tumor hypoxia quantified by ¹⁸F-misonidazole dynamics between weeks 0 and 2 of chemoradiation was associated with improved LRC (HR, 0.321; P = 0.015) and PFS (HR, 0.402; P = 0.043). Outcomes in the favorable early hypoxia resolution subgroup significantly depended on infiltrating lymphocyte counts, with patients who showed both an early hypoxia response and high lymphocyte infiltration levels exhibiting significantly improved LRC (HR, 0.259; P = 0.036) and PFS (HR, 0.242; P = 0.017) compared with patients with an early hypoxia response but low lymphocyte counts. These patients exhibited oncologic results comparable to those of patients with no hypoxia response within the first 2 wk of chemoradiation. Conclusion: This analysis established a clinical hypoxia-immune score that predicted treatment responses and outcomes in HNSCC patients undergoing chemoradiation and may help to devise novel concepts for biology-driven personalization of chemoradiation.

Hypoxia dynamics on FMISO-PET in combination with PD-1/PD-L1 expression has an impact on the clinical outcome of patients with Head-and-neck Squamous Cell Carcinoma undergoing Chemoradiation

Tumor-associated hypoxia influences the radiation response of head-and-neck cancer (HNSCC) patients, and a lack of early hypoxia resolution during treatment considerably deteriorates outcomes. As the detrimental effects of hypoxia are partly related to the induction of an immunosuppressive microenvironment, we investigated the interaction between tumor hypoxia dynamics and the PD-1/PD-L1 axis in HNSCC patients undergoing chemoradiation and its relevance for patient outcomes in a prospective trial.

Methods: 49 patients treated with definitive chemoradiation for locally advanced HNSCC were enrolled in this trial and received longitudinal hypoxia PET imaging using fluorine-18 misonidazole ([¹⁸F]FMISO) at weeks 0, 2 and 5 during treatment. Pre-therapeutic tumor biopsies were immunohistochemically analyzed regarding the PD-1/PD-L1 expression both on immune cells and on tumor cells, and potential correlations between the PD-1/PD-L1 axis and tumor hypoxia dynamics during chemoradiation were assessed using Spearman's rank correlations. Hypoxia dynamics during treatment were quantified by subtracting the standardized uptake value (SUV) index at baseline from the SUV values at weeks 2 or 5, whereby SUV index was defined as ratio of maximum tumor [¹⁸F]FMISO SUV to mean SUV in the contralateral sternocleidomastoid muscle (i.e. tumor-to-muscle ratio). The impact of the PD-1/PD-L1 expression alone and in combination with persistent tumor hypoxia on locoregional control (LRC), progression-free survival (PFS) and overall survival (OS) was examined using log-rank tests and Cox proportional hazards models.

Results: Neither PD-L1 nor PD-1 expression levels on tumor-infiltrating immune cells influenced LRC (HR = 0.734; p = 0.480 for PD-L1, HR = 0.991; p = 0.989 for PD-1), PFS (HR = 0.813; p = 0.597 for PD-L1, HR = 0.796; p = 0.713 for PD-1) or OS (HR = 0.698; p = 0.405 for PD-L1, HR = 0.315; p = 0.265 for PD-1). However, patients with no hypoxia resolution between weeks 0 and 2 and PD-L1 expression on tumor cells, quantified by a tumor proportional score (TPS) of at least 1%, showed significantly worse LRC (HR = 3.374, p = 0.022) and a trend towards reduced PFS (HR = 2.752, p = 0.052). In the multivariate Cox regression analysis, the combination of absent tumor hypoxia resolution and high tumoral PD-L1 expression remained a significant prognosticator for impaired LRC (HR = 3.374, p = 0.022). On the other side, tumoral PD-L1 expression did not compromise the outcomes of patients whose tumor-associated hypoxia declined between week 0 and 2 during chemoradiation (LRC: HR = 1.186, p = 0.772, PFS: HR = 0.846, p = 0.766).

Conclusion: In this exploratory analysis, we showed for the first time that patients with both persistent tumor-associated hypoxia during treatment and PD-L1 expression on tumor cells exhibited a worse outcome, while the tumor cells' PD-L1 expression did not influence the outcomes of patients with early tumor hypoxia resolution. While the results have to be validated in an independent cohort, these findings form a foundation to investigate the combination of hypoxic modification and immune checkpoint inhibitors for the unfavorable subgroup, moving forward towards personalized radiation oncology treatment.

Radiation Damage to Tumor Vasculature Initiates a Program That Promotes Tumor Recurrences

This review, mostly of preclinical data, summarizes the evidence that radiation at doses relevant to radiation therapy initiates a pathway that promotes the reconstitution of the tumor vasculature leading to tumor recurrence. The pathway is not specific to tumors; it promotes repair of damaged and ischemic normal tissues by attracting proangiogenic cells from the bone marrow. For irradiated tumors the pathway comprises: (1) loss of endothelial cells and reduced tumor blood perfusion leading to increased tumor hypoxia and increased levels of hypoxia inducible factor-1 (HIF-1). Alternatively, increased HIF-1 levels may arise by reactive oxygen species (ROS) production caused by tumor reoxygenation. (2) Increased HIF-1 levels lead to increased levels in the tumor of the chemokine stromal cell-derived factor-1 (SDF-1, CXCL12), which captures monocytes/macrophages expressing the CXCR4 receptor of CXCL12. (3) The increased levels of tumor-associated macrophages (TAMs) become highly proangiogenic (M2 polarized) and restore the tumor vasculature, thereby promoting tumor recurrence. The relevance of this pathway for radiation therapy is that it can be blocked in a number of different ways including by inhibitors of monocytes/macrophages, of HIF-1, of CXCL12, of CXCR4, and of CSF-1R, the latter of which is responsible for the M2 polarization of the TAMs. All of these inhibitors produce a robust enhancement of the radiation response of a wide variety of preclinical tumor models. Further, the same inhibitors actually provide protection against radiation damage of several normal tissues. Some of these pathway inhibitors are available clinically, and a first-in-human trial of the CXCR4 inhibitor, plerixafor, with radiation therapy of glioblastoma has yielded promising results, including an impressive increase in local tumor control. Further clinical trials are warranted.

CT imaging during treatment improves radiomic models for patients with locally advanced head and neck cancer

BACKGROUND AND PURPOSE

The development of radiomic risk models to predict clinical outcome is usually based on pre-treatment imaging, such as computed tomography (CT) scans used for radiation treatment planning. Imaging data acquired during the course of treatment may improve their prognostic performance. We compared the performance of radiomic risk models based on the pre-treatment CT and CT scans acquired in the second week of therapy.

MATERIAL AND METHODS

Treatment planning and second week CT scans of 78 head and neck squamous cell carcinoma patients treated with primary radiochemotherapy were collected. 1538 image features were extracted from each image. Prognostic models for loco-regional tumour control (LRC) and overall survival (OS) were built using 6 feature selection methods and 6 machine learning algorithms. Prognostic performance was assessed using the concordance index (C-Index). Furthermore, patients were stratified into risk groups and differences in LRC and OS were evaluated by log-rank tests.

RESULTS

The performance of radiomic risk model in predicting LRC was improved using the second week CT scans (C-Index: 0.79), in comparison to the pre-treatment CT scans (C-Index: 0.65). This was confirmed by Kaplan-Meier analyses, in which risk stratification based on the second week CT could be improved for LRC (p = 0.002) compared to pre-treatment CT (p = 0.063).

CONCLUSION

Incorporation of imaging during treatment may be a promising way to improve radiomic risk models for clinical treatment adaption, i.e., to select patients that may benefit from dose modification.

Do selective radiation dose escalation and tumour hypoxia status impact the loco-regional tumour control after radio-chemotherapy of head & neck tumours? The ESCALOX protocol

Background

Standard of care primary treatment of carcinoma of locally advanced squamous cell head and neck cancer (LAHNSCC) consists of platinum-based concomitant chemo-irradiation. Despite progress in the treatment of LAHNSCC using modern radiotherapy techniques the outcome remains still poor. Using IMRT with SIB the escalation of total dose to the GTV is possible with the aim to improve clinical outcome. This study tests the hypothesis if radiation dose escalation to the GTV improves 2-year-LRC and -OS after concomitant chemo-irradiation.

Methods

The ESCALOX trial is a prospective randomized phase III study using cisplatin chemo-irradiation and the SIB-IMRT concept in patients with LAHNSCC of the oral cavity, oropharynx or hypopharynx to escalate the total dose to the GTV up to 80.5 Gy. Chemotherapy is planned either in the 1^st and 5^th week (cisplatin 20 mg/m²/d d 1–5 and d 29–33) or weekly (cisplatin 40 mg/m²/d) during RT. RT is delivered as SIB with total doses of 80.5 Gy/70.0 Gy/56.0 Gy with 2.3 Gy/2.0 Gy and 1.6 Gy in the experimental arm and in the control arm with 70.0 Gy/56.0 Gy with 2.0 Gy and 1.6 Gy. A pre-study with dose escalation up to 77.0 Gy/70.0 Gy/56.0 Gy with 2.2 Gy/2.0 Gy and 1.6 Gy is demanded by the German federal office of radiation protection (BfS). In the translational part of the trial 100 of the randomised patients will be investigated by 18-F-FMiso-PET-CT for the presence and behaviour of tumor hypoxia twice in the week before treatment start.

Discussion

The primary endpoint of the pre-study is acute radiation induced toxicity. Primary endpoint of the main trial is 2-year-LRC. By using the dose escalation up to 80.5 Gy to the GTV of the primary tumor and lymph nodes > 2 cm a LRC benefit of 15% at 2 years should be expected. The ESCALOX trial is supported by Deutsche Forschungsgemeinschaft (DFG); Grant No.: MO-363/4-1.

Trial registration

ClinicalTrials.gov Identifier: NCT 01212354, EudraCT-No.: 2010-021139-15

Hypoxia in Head and Neck Tumors: Characteristics and Development during Therapy

Cancers of the head and neck are a malignancy causing a considerable health burden. In head and neck cancer patients, tumor hypoxia has been shown to be an important predictor of response to therapy and outcome. Several imaging modalities can be used to determine the amount and localization of tumor hypoxia. Especially PET has been used in a number of studies analyzing this phenomenon. However, only few studies have reported the characteristics and development during (chemoradio-) therapy. Yet, the characterization of tumor hypoxia in the course of treatment is of great clinical importance. Successful delineation of hypoxic subvolumes could make an inclusion into radiation treatment planning feasible, where dose painting is hypothesized to improve the tumor control probability. So far, hypoxic subvolumes have been shown to undergo changes during therapy; in most cases, a reduction in tumor hypoxia can be seen, but there are also differing observations. In addition, the hypoxic subvolumes have mostly been described as geographically rather stable. However, studies specifically addressing these issues are needed to provide more data regarding these initial findings and the hypotheses connected with them.

PET hypoxia imaging with FAZA: reproducibility at baseline and during fractionated radiotherapy in tumour-bearing mice

PURPOSE

Tumour hypoxia is linked to treatment resistance. Positron emission tomography (PET) using hypoxia tracers such as fluoroazomycin arabinoside (FAZA) may allow identification of patients with hypoxic tumours and the monitoring of the efficacy of hypoxia-targeting treatment. Since hypoxia PET is characterized by poor image contrast, and tumour hypoxia undergoes spontaneous changes and is affected by therapy, it remains unclear to what extent PET scans are reproducible. Tumour-bearing mice are valuable in the validation of hypoxia PET, but identification of a reliable reference tissue value (blood sample or image-derived muscle value) for repeated scans may be difficult due to the small size of the animal or absence of anatomical information (pure PET). Here tumour hypoxia was monitored over time using repeated PET scans in individual tumour-bearing mice before and during fractionated radiotherapy.

METHODS

Mice bearing human SiHa cervix tumour xenografts underwent a PET scan 3 h following injection of FAZA on two consecutive days before initiation of treatment (baseline) and again following irradiation with four and ten fractions of 2.5 Gy. On the last scan day, mice were given an intraperitoneal injection of pimonidazole (hypoxia marker), tumours were collected and the intratumoral distribution of FAZA (autoradiography) and hypoxia (pimonidazole immunohistology) were determined in cryosections.

RESULTS

Tissue section analysis revealed that the intratumoral distribution of FAZA was strongly correlated with the regional density of hypoxic (pimonidazole-positive) cells, even when necrosis was present, suggesting that FAZA PET provides a reliable measure of tumour hypoxia at the time of the scan. PET-based quantification of tumour tracer uptake relative to injected dose showed excellent reproducibility at baseline, whereas normalization using an image-derived nonhypoxic reference tissue (muscle) proved highly unreliable since a valid and reliable reference value could not be determined. The intratumoral distribution of tracer was stable at baseline as shown by a voxel-by-voxel comparison of the two scans (R = 0.82, range 0.72-0.90). During treatment, overall tracer retention changed in individual mice, but there was no evidence of general reoxygenation.

CONCLUSION

Hypoxia PET scans are quantitatively correct and highly reproducible in tumour-bearing mice. Preclinical hypoxia PET is therefore a valuable and reliable tool for the development of strategies that target or modify hypoxia.

Exploratory prospective trial of hypoxia-specific PET imaging during radiochemotherapy in patients with locally advanced head-and-neck cancer

PURPOSE

To explore in a prospective trial the prognostic value of hypoxia imaging before and during radiochemotherapy in patients with locally advanced head and neck cancer.

PATIENTS AND METHODS

Twenty-five patients with stage III/IV head and neck cancer were investigated with [(18)F]-fluoromisonidazole (FMISO) PET/CT at four time points during radiochemotherapy (baseline, 8-10 Gy, 18-20 Gy,50-60 Gy). FMISO PET/CT image parameters were extracted including maximum-tumour-to-background (TBR(max)) and thresholded volume at different TBR ratios. CT volume and baseline FDG-PET/CT image parameters were also included. Parameters at all time points were investigated for their prognostic value with the local-progression-free-survival endpoint (LPFS). Significance was evaluated with multivariate Cox (including clinical parameters) and Log-rank tests.

RESULTS

FMISO-image parameters were found to have a strong association with the LPFS endpoint, and were strongest at the week 1 and 2 time points (p = 0.023-0.048 and 0.042-0.061 respectively on multivariate Cox). Parameters measured at baseline were only significant on univariate analysis. None of the clinical parameters, and also FDG- or CT-delineated volumes, were significantly associated with LPFS.

CONCLUSION

This prospective, exploratory study demonstrated that FMISO-PET/CT imaging during the initial phase of treatment carries strong prognostic value. FMISO-PET/CT imaging at 1 or 2 weeks during treatment could be promising way to select patients that would benefit from hypoxia modification or dose-escalated treatment. A validation study is on-going.

The HYP-RT hypoxic tumour radiotherapy algorithm and accelerated repopulation dose per fraction study

The HYP-RT model simulates hypoxic tumour growth for head and neck cancer as well as radiotherapy and the effects of accelerated repopulation and reoxygenation. This report outlines algorithm design, parameterisation and the impact of accelerated repopulation on the increase in dose/fraction needed to control the extra cell propagation during accelerated repopulation. Cell kill probabilities are based on Linear Quadratic theory, with oxygenation levels and proliferative capacity influencing cell death. Hypoxia is modelled through oxygen level allocation based on pO₂ histograms. Accelerated repopulation is modelled by increasing the stem cell symmetrical division probability, while the process of reoxygenation utilises randomised pO₂ increments to the cell population after each treatment fraction. Propagation of 10⁸ tumour cells requires 5–30 minutes. Controlling the extra cell growth induced by accelerated repopulation requires a dose/fraction increase of 0.5–1.0 Gy, in agreement with published reports. The average reoxygenation pO₂ increment of 3 mmHg per fraction results in full tumour reoxygenation after shrinkage to approximately 1 mm. HYP-RT is a computationally efficient model simulating tumour growth and radiotherapy, incorporating accelerated repopulation and reoxygenation. It may be used to explore cell kill outcomes during radiotherapy while varying key radiobiological and tumour specific parameters, such as the degree of hypoxia.

Radiation-induced vascular damage in tumors: implications of vascular damage in ablative hypofractionated radiotherapy (SBRT and SRS)

We have reviewed the studies on radiation-induced vascular changes in human and experimental tumors reported in the last several decades. Although the reported results are inconsistent, they can be generalized as follows. In the human tumors treated with conventional fractionated radiotherapy, the morphological and functional status of the vasculature is preserved, if not improved, during the early part of a treatment course and then decreases toward the end of treatment. Irradiation of human tumor xenografts or rodent tumors with 5-10 Gy in a single dose causes relatively mild vascular damages, but increasing the radiation dose to higher than 10 Gy/fraction induces severe vascular damage resulting in reduced blood perfusion. Little is known about the vascular changes in human tumors treated with high-dose hypofractionated radiation such as stereotactic body radiotherapy (SBRT) or stereotactic radiosurgery (SRS). However, the results for experimental tumors strongly indicate that SBRT or SRS of human tumors with doses higher than about 10 Gy/fraction is likely to induce considerable vascular damages and thereby damages the intratumor microenvironment, leading to indirect tumor cell death. Vascular damage may play an important role in the response of human tumors to high-dose hypofractionated SBRT or SRS.

Various doses of fractioned irradiation modulates multidrug resistance 1 expression differently through hypoxia-inducible factor 1α in esophageal cancer cells

To evaluate the effect of different regimen of radiotherapy on multidrug resistance 1 (MDR1) expression and analyze the role hypoxia-inducible factor 1α (HIF1α) played in the whole process. Fifty-four cell lines established from 96 esophageal cancer biopsy samples were given various doses of fractioned irradiation. The mRNA and protein levels of HIF1α and MDR1 post-irradiation were measured by quantitative reverse transcription-polymerase chain reaction and Western blot analysis, respectively. HIF1α-siRNA was used to verify the effect of HIF1α on radiation-mediated MDR1 modulation. In esophageal cancer cells surviving 28 Gy irradiation (2 Gy/f, 14 fractions), MDR1 mRNA expression increased 65.27 ± 5.58%, and HIF1α was elevated by 27.21 ± 2.25%. Interestingly, their expression decreased by 54.38 ± 11.53% and 32.08 ± 4.75% after 7 Gy irradiation (0.5 Gy/f, 14 fractions). HIF1α expression showed a positive correlation with MDR1 expression in the whole process (P < 0.05). Silencing of HIF1α decreased MDR1 expression and blocked changes in MDR1 and HIF1α expression induced by fractioned irradiation. These results indicate that MDR1 is differentially modulated by different doses of fractionated radiation, which should be taken into account when combining radiotherapy and chemotherapy for patients with esophageal cancer.

Severe hypofractionation: non-homogeneous tumour dose delivery can counteract tumour hypoxia

BACKGROUND

The current rationale for severely hypofractionated schedules (3-5 fractions) used in stereotactic-body-radiotherapy (SBRT) of non-small-cell lung cancer (NSCLC) is the small size of the irradiated volumes. Being the dose prescribed to the 60-80% isodose line enclosing the PTV, a non-homogeneous tumour-dose-delivery results which might impact on tumour hypoxia. A comparison between homogeneous and SBRT-like non-homogeneous tumour-dose-delivery is then proposed here, using severe hypofractionation on large tumour volumes where both dose prescription strategies are applicable.

MATERIALS AND METHODS

For iso-NTCP hypofractionated schedules (1f/d*5d/w) with respect to standard fractionation (d=2Gy), computed from the individual DVHs for lungs, oesophagus, heart and spinal cord (Lyman-Kutcher-Burman NTCP-model), TCP values were calculated (α-averaged Poissonian-LQ model) for homogeneous and SBRT-like non-homogeneous plans both with and without tumour hypoxia. Two different estimates of the oxygen-enhancement-ratio (OER) in combination with two distinct assumptions on the kinetics of reoxygenation were considered. Homogeneous and SBRT-like non-homogeneous plans were finally compared in terms of therapeutic ratio (TR), as the product of TCP and the four (1-NTCP(i)) values.

RESULTS

For severe hypofractionation (3-5 fractions) and for any of the hypotheses on the kinetics of reoxygenation and the OER, there was a significant difference between the computed TRs with or without inclusion of tumour hypoxia (anova, p=0.01) for homogeneous tumour-dose-delivery, but no significant difference for the SBRT-like non-homogeneous one. Further, a significantly increased mean TR for the group of SBRT-like non-homogeneous plans resulted (t-test, p=0.05) with respect to the group with homogeneous target-dose-coverage.

CONCLUSIONS

SBRT-like dose-boosting seems to counterbalance the loss of reoxygenation within a few fractions. For SBRT it then seems that, in addition to the high level of dose-sparing to the adjacent normal tissues, when severe hypofractionation is adopted it is probably the intrinsic ability of stereotactic techniques to perform intra-tumour simultaneous dose-boosting which yields the reported high clinical efficacy.

Measurement of reoxygenation during fractionated radiotherapy in head and neck squamous cell carcinoma xenografts

Hypoxic tissues lack adequate oxygenation and it has been long established that tumours commonly exhibit hypoxia and that hypoxia is a factor contributing towards resistance to radiotherapy. To develop computer models and make predictions about the affects of tumour hypoxia on treatment outcome, quantitative tumour oxygenation and reoxygenation data from in vivo systems is required. The aim of this study was to investigate the timing and degree of reoxygenation during radiotherapy in a human head and neck squamous cell carcinoma xenograft mouse model (FaDu). Mice were immobilised using a novel restraining system and exposed unanaesthetised in 3 or 5 Gy fractions, up to a maximum of 40 Gy. Partial pressures of oxygen (pO2) measurements were recorded at six time points throughout the 2 week course of radiotherapy, using a fibre optic system. Tumours receiving 0-30 Gy did not exhibit an increase in pO2. However, the mean pO2 after 2 weeks of accelerated fractionated radiotherapy (40 Gy) was significantly increased (P<0.01) compared to the mean pO2 of tumours not receiving the full schedule (0-30 Gy). These results lead to the conclusion of an average reoxygenation onset time of 2 weeks in this group of xenografts. A relatively large range of pO2 values measured at each dose point in the study indicate a large inter-tumour variation in oxygenation among the tumours. Data from this experimental work will be used to define the range of reoxygenation onset times implemented in a Monte Carlo computer model, simulating hypoxic head and neck cancer growth and radiotherapy.

Efficient Monte Carlo modelling of individual tumour cell propagation for hypoxic head and neck cancer

A Monte Carlo tumour model has been developed to simulate tumour cell propagation for head and neck squamous cell carcinoma. The model aims to eventually provide a radiobiological tool for radiation oncology clinicians to plan patient treatment schedules based on properties of the individual tumour. The inclusion of an oxygen distribution amongst the tumour cells enables the model to incorporate hypoxia and other associated parameters, which affect tumour growth. The object oriented program FORTRAN 95 has been used to create the model algorithm, with Monte Carlo methods being employed to randomly assign many of the cell parameters from probability distributions. Hypoxia has been implemented through random assignment of partial oxygen pressure values to individual cells during tumour growth, based on in vivo Eppendorf probe experimental data. The accumulation of up to 10 million virtual tumour cells in 15 min of computer running time has been achieved. The stem cell percentage and the degree of hypoxia are the parameters which most influence the final tumour growth rate. For a tumour with a doubling time of 40 days, the final stem cell percentage is approximately 1% of the total cell population. The effect of hypoxia on the tumour growth rate is significant. Using a hypoxia induced cell quiescence limit which affects 50% of cells with and oxygen levels less than 1 mm Hg, the tumour doubling time increases to over 200 days and the time of tumour growth for a clinically detectable tumour (10(9) cells) increases from 3 to 8 years. A biologically plausible Monte Carlo model of hypoxic head and neck squamous cell carcinoma tumour growth has been developed for real time assessment of the effects of multiple biological parameters which impact upon the response of the individual patient to fractionated radiotherapy.

Detection and characterization of tumor hypoxia using pO2 histography

Data from 125 studies describing the pretreatment oxygenation status as measured in the clinical setting using the computerized Eppendorf pO2 histography system have been compiled in this article. Tumor oxygenation is heterogeneous and severely compromised as compared to normal tissue. Hypoxia results from inadequate perfusion and diffusion within tumors and from a reduced O2 transport capacity in anemic patients. The development of tumor hypoxia is independent of a series of relevant tumor characteristics (e.g., clinical size, stage, histology, and grade) and various patient demographics. Overall median pO2 in cancers of the uterine cervix, head and neck, and breast is 10 mm Hg with the overall hypoxic fraction (pO2 <or= 2.5 mm Hg) being approx. 25%. Metastatic lesions do not substantially deviate from the oxygenation status of (their) primary tumors. Whereas normal tissue oxygenation is independent of the hemoglobin level over the range of 8-15 g/dL, hypoxia is more pronounced in anemic patients and above this range in some cancers. Identification of tumor hypoxia may allow an assessment of a tumor's potential to develop an aggressive phenotype or acquired treatment resistance, both of which lead to poor prognosis. Detection of hypoxia in the clinical setting may therefore be helpful in selecting high-risk patients for individual and/or more intensive treatment schedules.

Split course hyperfractionated accelerated radio-chemotherapy (SCHARC) for patients with advanced head and neck cancer: influence of protocol deviations and hemoglobin on overall survival, a retrospective analysis

Background

The advantage of hyperfractionated accelerated radiation therapy for advanced head and neck cancer has been reported. Furthermore, randomized trials and meta-analyses have confirmed the survival benefit of additional chemotherapy to radiotherapy. We retrospectively analyzed the efficiency and toxicity of the Regensburg standard therapy protocol "SCHARC" and the overall survival of our patients.

Methods

From 1997 to 2004, 64 patients suffering from advanced head and neck cancer (88 % stage IV, 12 % stage III) were assigned to receive the SCHARC protocol. Around half of the patients were diagnosed with oro-hypopharynx carcinoma (52 %), one third with tongue and floor of mouth tumors (29 %) and one fifth (19 %) suffered from H & N cancer at other sites. The schedule consisted of one therapy block with 30 Gy in 20 fractions over a two week period with concomitant chemotherapy (d 1–5: 20 mg/m²/d DDP + 750–1000 mg/m²/d 5FU (cont. infusion). This therapy block was repeated after a fortnight break up to a cumulative dose of 60 Gy and followed by a boost up to 70 Gy (69–70.5 Gy). All patients assigned to this scheme were included in the survival evaluation.

Results

Forty patients (63 %) received both radiation and chemotherapy according to the protocol. The mean follow up was 2.3 years (829 d) and the median follow up was 1.9 years (678 d), respectively. The analysis of survival revealed an estimated 3 year overall survival rate of 57 %. No patient died of complications, 52 patients (80 %) had acute grade 2–3 mucositis, and 33 patients (58 %) suffered from acute grade 3 skin toxicity. Leucopenia was no major problem (mean nadir 3.4 g/nl, no patient < 1.0 g/nl) and the mean hemoglobin value decreased from 13.2 to 10.5 g/dl. Univariate analysis of survival showed a better outcome for patients with a hemoglobin nadir >10.5 g/dl and for patients who completed the protocol.

Conclusion

The SCHARC protocol was effective in patients diagnosed with advanced head and neck cancer. It led to long-term disease control and survival in about 50 % of the patients with significant but acceptable toxicity. Most patients were not anemic at beginning of therapy. Therefore, we could assess the influence of pre-treatment hemoglobin on survival. However, a low hemoglobin nadir was associated with poor outcome. This result suggests an influence of anemia during therapy on prognosis.

Carbon beam therapy overcomes the radiation resistance of uterine cervical cancer originating from hypoxia

PURPOSE

High linear energy transfer (LET) particles are believed to decrease tumor radiation resistance originating from hypoxia. However, no proof of this effect has been provided by clinical trials and related clinical research. Hence, we investigated the radiation biological aspects of high LET carbon beam therapy on cervical cancer.

EXPERIMENTAL DESIGN

This study involved 49 patients with stage IIIb bulky and stage IVa cervical cancer treated with high LET carbon beams between October 1995 and June 2000. Oxygen partial pressure (pO(2)) was measured by using a needle-type polarographic oxygen electrode.

RESULTS

The 4-year disease-free survival rates of patients with pO(2) </= 20 mm Hg (hypoxic tumor) and pO(2) > 20 mm Hg (oxygenated tumor) before treatment were 37% and 21%, respectively. The local control rates of hypoxic and oxygenated tumors before treatment were 58% and 54%, respectively. The disease-free survival rates of hypoxic and oxygenated tumors assessed by oxygen status at the 5th day of irradiation were 33% and 32%, respectively. The local control rates of hypoxic and oxygenated tumors at the 5th day were 60% and 58%, respectively. There was no significant prognostic difference between hypoxic and oxygenated tumors.

CONCLUSION

The similar disease-free survival and local control rates between hypoxic and oxygenated tumors before and during treatment indicated that the role of the tumor oxygenation status was not so important in local control in carbon beam therapy. These results indicated that high LET carbon beam irradiation might reduce the radiation-resistant nature stemming from tumor hypoxia.

Oxygenated and reoxygenated tumors show better local control in radiation therapy for cervical cancer

The presence of hypoxic cells is one of the major factors affecting resistance against radiation therapy. In the clinical setting, little information exists as to the relationship between intratumoral oxygen partial pressure (pO(2)) and outcome. This study involved 30 consecutive patients with cervical cancer, who were treated with a combination of external and high-dose rate intracavitary irradiation. The pO(2) was measured before radiation therapy and at 9 Gy, using a needle-type polarographic oxygen electrode. The mean intratumoral pO(2) before radiation therapy was 17.3 +/- 10.8 mm Hg. The 3-year local control rates of patients with pO(2)< or = 20 mm Hg and pO(2) > 20 mm Hg before radiation therapy were 52% and 100%, respectively, representing a significant difference (P= 0.035). At 9 Gy, mean intratumoral pO(2) was 23.6 +/- 9.1 mm Hg, a significant increase compared to the value before radiation therapy (P= 0.006). The 3-year local control rates of tumors with pO(2)< or = 20 mm Hg and pO(2) > 20 mm Hg at 9 Gy were 35% and 93%, respectively, representing a significant difference (P= 0.001). The significantly better local control for oxygenated tumors at 9 Gy as well as before radiation therapy indicated that the oxygen effect and reoxygenation by radiation played an important role in local control in radiation therapy for cervical cancer.

Severity, risk factors, and physician practices in the management of anemia during concurrent chemoradiation for head and neck carcinoma

BACKGROUND

Anemia is a well-recognized complication of concurrent chemoradiation therapy for head and neck carcinoma. It impairs quality of life and many studies also have reported an association between anemia and increased tumor recurrence and decreased long-term survival. In the current study, the authors attempted to identify the severity, risk factors, and physician practices in the management of anemia.

METHODS

Medical records of those patients receiving concurrent chemoradiation for head and neck carcinoma between 1999-2003 were reviewed. The average weekly nadir hemoglobin level (AWNH) was defined as the mean value of the lowest hemoglobin concentration in each week. Independent predictors for an AWNH < 11 g/dL were identified using multivariable logistic regression analyses.

RESULTS

Seventy-two patients were included in the current study, 66.7% of whom had unresectable disease. The overall median survival was 402 days. At baseline, 76.4% (95% confidence interval [95% CI], 66.3-86.4%) of patients already had a hemoglobin level < 13.5 g/dL. The hemoglobin level dropped 2.5 +/- 1.9 g/dL during concurrent chemoradiation, resulting in 95.8% of patients having a hemoglobin level < 13.5 g/dL at the end of the observation period. Blood was transfused to 24 patients (33.3%); erythropoietin or darbepoietin was administered to 2 patients (2.7%). The mean lowest hemoglobin threshold of transfusion was 7.3 +/- 1.0 g/dL. The cumulative percentage of patients who received a transfusion reached 50% when the mean nadir hemoglobin level was 7.4 g/dL. Independent predictors of an AWNH < 11.0 g/dL were low baseline hemoglobin and receiving multiple concurrent chemotherapeutic agents, with relative risks of 13.6 and 1.8, respectively (95% CI,1.9-93.9 and 1.1-3.1, respectively).

CONCLUSIONS

Anemia is prevalent in patients undergoing treatment for head and neck carcinoma and can be severe with concurrent chemoradiation therapy. However, the intensity of anemia management is low. A low baseline hemoglobin level and the reception of multiple concurrent chemotherapeutic agents are considered to be the main risk factors of anemia. Cancer 2006.

Fluctuations in pO2 in irradiated human melanoma xenografts

Several studies have demonstrated that untreated tumors may show significant fluctuations in tissue oxygen tension (pO(2)). Radiation treatment may induce changes in the tumor microenvironment that alter the pO(2) fluctuation pattern. The purpose of the present study was to investigate whether pO(2) fluctuations may also occur in irradiated tumors. A-07 human melanoma xenografts were irradiated with single doses of 0, 5 or 10 Gy. Fluctuations in pO(2) were recorded with OxyLite probes prior to irradiation and 24 and 72 h after the radiation exposure. Radiation-induced changes in the tumor microenvironment (i.e. blood perfusion and extracellular volume fraction) were assessed by dynamic contrast-enhanced magnetic resonance imaging. Seventy-two hours after 10 Gy, tumor blood perfusion had decreased to approximately 40% of that prior to irradiation, whereas the extracellular volume fraction had increased by approximately 25%. Fluctuations in pO(2) were seen in most tumors, irrespective of radiation dose and time after irradiation. The mean pO(2), the number of fluctuations around the mean pO(2), the number of fluctuations around threshold pO(2) values of 1, 2, 3, 5, 7 and 10 mmHg, and the amplitude of the fluctuations were determined for each pO(2) trace. No significant differences were detected between irradiated and unirradiated tumors. The results showed that pO(2) fluctuations may occur in irradiated tumors and that the pO(2) fluctuation pattern in A-07 tumors exposed to 5 or 10 Gy is similar to that in untreated tumors. Consequently, these doses did not induce changes in the tumor microenvironment that were sufficient to cause detectable alterations in the pO(2) fluctuation pattern.

Radiation Modifiers: Treatment Overview and Future Investigations

Many radiosensitizers are in current clinical use. In addition, a myriad of potential new targeted therapies, which may also interact with radiation, are in clinical development. The clinical utility of new targeted therapies, in combination with existing radiation sensitizers (chemotherapies) requires further evaluation, as does the understanding of their acute and late radiation effects. Free radical scavengers appear to show promise as radioprotectors, but data for mucoprotection are less convincing.

Fluctuations in pO2 in poorly and well-oxygenated spontaneous canine tumors before and during fractionated radiation therapy

BACKGROUND AND PURPOSE

The spatial heterogeneity in oxygen tension (pO2) in tumor tissue has been studied extensively, whereas, the information about the temporal heterogeneity is sparse. The purpose of the present study was to search for pO2 fluctuations in untreated and irradiated spontaneous canine tumors, and to investigate whether there is a relationship between overall tumor oxygenation status and pO2 fluctuation pattern.

PATIENTS AND METHODS

Six dogs scheduled for radiation therapy of head and neck cancer were included in the study. The primary tumors were irradiated with 18 fractions of 3 Gy. Eppendorf polarographic electrodes and OxyLite fluorescence probes were used to measure overall oxygenation status and pO2 fluctuation pattern, respectively. Tissue pO2 was recorded at three subsequent days prior to treatment, and immediately before radiation fraction 4, 7, and 10.

RESULTS

Overall oxygenation status differed substantially among the tumors. Radiation therapy had no consistent effect on overall oxygenation status. Fluctuations in pO2 were detected in untreated as well as irradiated tumors, and independent of whether the tumors were poorly or well oxygenated.

CONCLUSIONS

Fluctuations in pO2 can occur in untreated and irradiated spontaneous canine tumors. There is no correlation between pO2 fluctuation pattern and overall tumor oxygenation status.

Optical tomography with ultrasound localization: initial clinical results and technical challenges

Optical tomography with ultrasound localization utilizes co-registered ultrasound lesion structure information to guide optical imaging reconstruction. A hand-held probe consisting of a commercial ultrasound transducer and near infrared optical imaging sensors was used to simultaneously acquire ultrasound images and optical measurements. A dual-mesh scheme was used to map the ultrasound-visible lesions to finer-grid lesion regions and coarser-grid background regions for optical imaging reconstruction. As a result, optical imaging reconstruction was well-conditioned for inverse mapping of lesion hemoglobin concentration and blood oxygen saturation. Initial clinical results have shown that early stage invasive cancers may be distinguished by a two-fold greater total hemoglobin concentration compared with fibroadenomas and other benign lesions. Initial results of advanced cancers have shown that the hemoglobin distribution is highly distorted and heterogeneous and the distorted distributions correlate with histological microvessel density counts and could be used to assess chemotherapy response.

On the surviving fraction in irradiated multicellular tumour spheroids: calculation of overall radiosensitivity parameters, influence of hypoxia and volume effects

We model the heterogeneous response to radiation of multicellular tumour spheroids assuming position- and volume-dependent radiosensitivity. We propose a method to calculate the overall radiosensitivity parameters to obtain the surviving fraction of tumours. A mathematical model of a spherical tumour with a hypoxic core and a viable rim which is a caricature of a real tumour is constructed. The model is embedded in a two-compartment linear-quadratic (LQ) model, assuming a mixed bivariated Gaussian distribution to attain the radiosensitivity parameters. Ergodicity, i.e., the equivalence between ensemble and volumetric averages is used to obtain the overall radiosensitivities for the two compartments. We obtain expressions for the overall radiosensitivity parameters resulting from the use of both a linear and a nonlinear dependence of the local radiosensitivity with position. The model's results are compared with experimental data of surviving fraction (SF) for multicellular spheroids of different sizes. We make one fit using only the smallest spheroid data and we are able to predict the SF for the larger spheroids. These predictions are acceptable particularly using bounded sensitivities. We conclude with the importance of taking into account the contribution of clonogenic hypoxic cells to radiosensitivity and with the convenience of using bounded local sensitivities to predict overall radiosensitivity parameters.

Darbepoietin Alfa Potentiates the Efficacy of Radiation Therapy in Mice with Corrected or Uncorrected Anemia

Darbepoietin alfa (DA) is a long-acting analogue of erythropoietin that has reduced receptor affinity and enhanced biological activity. Experiments were done to test the hypothesis that correction of anemia in tumor-bearing mice by DA would increase tumor oxygenation and potentiate radiation-induced tumor cell killing. A SCC VII tumor model was used to study tumor responses to fractionated radiation therapy in mice with anemia induced by total body irradiation. Administration of DA reduced the extent and duration of anemia and associated tumor hypoxia, protected the bone marrow cells and prevented the body weight loss from the effect of irradiation, and facilitated the recovery in a time-dependent manner, with the administration of DA prior to total body irradiation having the greatest protective effect. When combined with fractionated radiation therapy, DA increased the tumor growth delay time from 2.7 days for irradiation alone to 7.3 to 10.6 days for combination of DA and irradiation. The effect of DA on tumor responses to fractionated radiation therapy was observed when DA was given 18 to 4 days before starting radiation therapy, but DA was also equally effective as a radiosensitizer when given only 2 hours before fractionated irradiation therapy. Weekly dosing of DA was as efficacious for the enhancement of radiation responses of tumors as biweekly dosing. Similar results were obtained in the RIF-1 fibrosarcoma tumor model. These studies show that DA can effectively correct anemia in tumor-bearing mice and sensitize tumor cells to fractionated radiation therapy. Importantly, DA was also able to sensitize tumors to radiation in mice with uncorrected anemia and hypoxia, suggesting that the effect of DA on radiosensitivity was independent of these factors and a different mechanism of action may be responsible for this effect.

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.

Heat shock protein 70 (Hsp70) membrane expression on head-and-neck cancer biopsy-a target for natural killer (NK) cells

PURPOSE

Heat shock protein 70 (Hsp70) was detected on the cell membrane of human tumor cell lines, but not on normal cells. Here we studied Hsp70 membrane expression as a target for natural killer (NK) cells on tumor material and control tissues of head-and-neck cancer patients.

METHODS AND MATERIALS

Membrane-bound Hsp70 was determined by flow cytometry on single-cell suspensions of tumors and the corresponding normal tissues of head-and-neck cancer patients. The cytolytic activity of NK cells against Hsp70-positive tumor cells was measured in a standard cytotoxicity assay.

RESULTS

In total, 54 of 74 primary tumors were found to be Hsp70 membrane-positive (73%); tongue/mouth, 21 of 24 (88%); oropharynx, 13 of 20 (65%); hypopharynx, 3 of 6 (50%); larynx, 8 of 11 (73%); trachea 1 of 2 (50%); esophagus, 4 of 5 (80%); lymph node metastases, 4 of 6 (67%). The corresponding control tissue was negative for membrane-bound Hsp70. Biopsies (6 of 6) of patients after in vivo gamma-irradiation (fractionated 5 x 2 Gy) were strongly Hsp70 membrane-positive. Irradiated, Hsp70-positive tumor cells are targets for Hsp70-peptide stimulated NK cells.

CONCLUSION

An irradiation-inducible, tumor-selective Hsp70 membrane localization provides a target structure for Hsp70-peptide stimulated human NK cells.

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.

Radiotherapy combined with simultaneous chemotherapy with mitomycin-C and 5-fluorouracil for inoperable head and neck cancer

The feasibility and effectiveness of a combined chemoradiotherapy treatment modality for locally advanced head and neck cancer was tested in a phase II trial. From March 1995 to June 1998, 35 patients with advanced squamous cell carcinoma of the head and neck were treated with a continuous intravenous infusion of 5-fluorouracil (600 mg m-2 24 h-1 for Days 1 to 5 (120 h)) and mitomycin-C (10 mg m-2 intravenously) on Day 5 during the first week of radiotherapy and on Day 36. 31 patients had stage IV disease; 4 patients had stage III; and 1 patient had stage II. Patient ages ranged from 42-69 years (median 56.7 years). The tumours involved were as follows: oral cavity (n = 11); oropharynx (n = 14); hypopharynx/larynx (n = 10). Radiotherapy was delivered to a total dose of 70 Gy with conventional fractionation (2 Gy per fraction, five times a week). Chemotherapy was well tolerated and all patients received the intended dose. Mild nausea occurred in five patients. After a mean follow-up of 21 months (range 10-44 months), 8 (23%) patients remain alive. A complete response was seen in 28 (80%) patients. When a recurrence appeared, it was within the first year after treatment. 1- and 2-year overall survival rates were 46% and 23%, respectively. Grade 3 mucositis occurred in 17% of patients. Grade 1-2 thrombopaenia occurred in 3 (9%) patients, grade > 2 leukopaenia in 4 (11%) patients, and grade > or = 2 anaemia in 3 (9%) patients. We observed a treatment interruption of maximum 1 week for six patients owing to mucositis. Febrile neutropaenia or aplasia were not observed. The concomitant use of 5-fluorouracil, mitomycin-C and radiotherapy in locally advanced head and neck carcinoma is well tolerated in this group of patients. This protocol showed good locoregional response with a very low toxicity profile.

Ultrasonographic assessment for response to radiochemotherapy of metastatic cervical lymph nodes in head and neck cancer: usefulness of grey-scale and color doppler sonography

To predict the response of lymph node metastasis to preoperative radiochemotherapy sonographically, the correlation between ultrasonographs and histologic features was retrospectively examined in 43 metastatic cervical lymph nodes from 24 patients with squamous cell carcinoma in the oral and maxillofacial region. Ultrasonographs were compared among poor-, good-, and complete-response lymph nodes. Before radiochemotherapy, hypoechoic internal echo and intranodal blood perfusion demonstrated many complete-response nodes; in contrast, most poor-response nodes showed peripheral blood perfusion and an avascular pattern, but did not have specific internal echo intensity. Complete-response nodes showed a significant reduction in their maximum and minimum diameters after radiochemotherapy. These results indicate that ultrasonography is useful for predicting the response of cervical lymph node metastasis to radiochemotherapy.

Dynamic optimization of a linear-quadratic model with incomplete repair and volume-dependent sensitivity and repopulation

PURPOSE

The linear-quadratic model typically assumes that tumor sensitivity and repopulation are constant over the time course of radiotherapy. However, evidence suggests that the growth fraction increases and the cell-loss factor decreases as the tumor shrinks. We investigate whether this evolution in tumor geometry, as well as the irregular time intervals between fractions in conventional hyperfractionation schemes, can be exploited by fractionation schedules that employ time-varying fraction sizes.

METHODS

We construct a mathematical model of a spherical tumor with a hypoxic core and a viable rim, which is most appropriate for a prevascular tumor, and is only a caricature of a vascularized tumor. This model is embedded into the traditional linear-quadratic model by assuming instantaneous reoxygenation. Dynamic programming is used to numerically compute the fractionation regimen that maximizes the tumor-control probability (TCP) subject to constraints on the biologically effective dose of the early and late tissues.

RESULTS

In several numerical examples that employ five or 10 fractions per week on a 1-cm or 5-cm diameter tumor, optimally varying the fraction sizes increases the TCP significantly. The optimal regimen incorporates large Friday (afternoon, if 10 fractions per week) fractions that are escalated throughout the course of treatment, and larger afternoon fractions than morning fractions.

CONCLUSION

Numerical results suggest that a significant increase in tumor cure can be achieved by allowing the fraction sizes to vary throughout the course of treatment. Several strategies deserve further investigation: using larger fractions before overnight and weekend breaks, and escalating the dose (particularly on Friday afternoons) throughout the course of treatment.

An analysis of the relationship between radiosensitivity and volume effects in tumor control probability modeling

The dependence of local tumor control probability (tcp) on tumor volume is analyzed and discussed with the help of radiobiological modeling; in particular the impact of possible correlations between mean tumor radiosensitivity and tumor dimensions on the tcp volume dependence is explored. The linear-quadratic Poissonian tumor control probability (tcp) model was modified to account for the possible dependence of clonogenic cell density and radiosensitivity parameters on tumor volume; then the original and modified versions of the model were fitted to published clinical and laboratory tumor control data. These different versions of the tcp model often fitted tumor control data equally well, because of the high degree of correlation between the parameters. Nevertheless the results were very different from a physical point of view and we suggest that sometimes it is possible to choose between equally good fits on the basis of physical considerations. Possible links between the volume dependence of the mean radiosensitivity and the degree of tumor hypoxia were also analyzed through a comparison of the results of the tcp fit to published measurements of oxygen tension in tumors.

Radiotherapy in head and neck cancer in the elderly: a challenge

Elderly patients represent the most rapidly growing subgroup of the patient population in France and in the majority of industrialized countries. The effect of age in terms of the prognosis and response to treatment remains unclear. The management strategy (curative versus palliative) for head and neck cancer in the elderly has given vent to divergent opinions and controversies in several respects (the type and quality of treatment, quality of life and economic consequences). This review only focuses on the radiotherapy schedule and head and neck cancers. We compare aged patients with head and neck cancer to younger patients in terms of clinical features, tumor biology, type of treatment, side effects and response. We conclude that if the patient is in a good general condition following a complete evaluation of the cancer, physicians should propose curative treatment with radiotherapy because retrospective trials demonstrate that response in older patients when treated aggressively is comparable to that of younger patients. However, specific trials concerning aged patients with head and neck cancer, quality of life and radiotherapy are warranted.

Microenvironment-induced cancer metastasis

PURPOSE

To present and evaluate clinical data suggesting that cancer metastasis may be induced by the microenvironment of the primary tumour and to discuss possible mechanisms of microenvironment-induced metastasis, based on a critical review of relevant data from studies of experimental tumours and cells in culture.

CONCLUSIONS

Low oxygen tension in the primary tumour is associated with metastasis in soft tissue sarcoma, cervix carcinoma and carcinoma of the head and neck. Multiple mechanisms may be involved in hypoxia-induced metastasis. Thus, hypoxia followed by reoxygenation may induce point mutations and DNA strand breakage leading to deletions, amplifications and genomic instability. Hypoxia may also provide a physiological pressure in tumours selecting for metastatic cell phenotypes. Moreover, hypoxia may induce a temporary increase in the expression of gene products involved in the metastatic cascade, either through gene amplifications or through normal physiological processes by activating oxygen sensors, hypoxia signal transduction pathways and DNA transcription factors. Low glucose concentration, high lactate concentration and low extracellular pH may induce metastasis by similar mechanisms as hypoxia. Tumour reoxygenation during radiation therapy may promote microenvironment-induced metastasis by rescuing hypoxic or nutritionally deprived metastatic cells from dying. Ionizing radiation can elicit a stress response in tumour cells similar to that elicited by hypoxia. Radiation therapy may therefore adversely affect the rate of metastasis in patients who do not achieve control of the primary tumour by enhancing the expression of gene products of importance in metastasis.

Changes in blood perfusion and hypoxia after irradiation of a human squamous cell carcinoma xenograft tumor line

The effect of irradiation depends on the oxygenation status of the tissue, while irradiation itself also changes the oxygenation and perfusion status of tissues. A better understanding of the changes in tumor oxygenation and perfusion over time after irradiation will allow a better planning of fractionated radiotherapy in combination with modifiers of blood flow and oxygenation. Vascular architecture (endothelial marker), perfusion (Hoechst 33342) and oxygenation (pimonidazole) were studied in a human laryngeal squamous cell carcinoma tumor line grown as xenografts in nude mice. The effect of a single dose of 10 Gy X rays on these parameters was evaluated from 2 h to 11 days after irradiation. Shortly after irradiation, there was an 8% increase in perfused blood vessels (from 57% to 65%) followed by a significant decrease, with a minimum value of 42% at 26 h after irradiation, and a subsequent increase to control levels at 7 to 11 days after irradiation. The hypoxic fraction showed a decrease at 7 h after treatment from 13% to 5% with an increase to 19% at 11 days after irradiation. These experiments show that irradiation causes rapid changes in oxygenation and perfusion which may have consequences for the optimal timing of radiotherapy schedules employing multiple fractions per day and the introduction of oxygenation- and perfusion-modifying drugs.

Pretreatment apoptosis in carcinoma of the cervix correlates with changes in tumour oxygenation during radiotherapy

A relationship between hypoxia and apoptosis has been identified in vitro and in experimental tumours. The aim of this study was to investigate the relationship between apoptosis, hypoxia and the change in oxygenation during radiotherapy in human squamous cell carcinoma of the cervix. Forty-two patients with locally advanced disease underwent pretreatment evaluation of tumour oxygenation using an Eppendorf computerized microneedle electrode. Twenty-two of these patients also had a second evaluation of tumour oxygenation after receiving 40-45 Gy external beam radiotherapy. Paraffin-embedded histological sections were obtained from random pretreatment biopsies for all 42 patients. Apoptotic index (AI) was quantified by morphology on TUNEL stained sections. No correlation was found between pretreatment measures of AI and either the median pO2 (r = 0.12, P = 0.44) or percentage of values < 5 mmHg (r = -0.02, P = 0.89). A significant positive correlation was found between AI and the change in tumour oxygenation (ratio of pre:post-treatment % values < 5 mmHg) following radiotherapy (r = 0.61, P = 0.002). The lack of correlation between apoptosis and hypoxia may occur because the Eppendorf measures both acute and chronic hypoxia, and the relative ability of acute hypoxia to induce apoptosis is unknown. These results indicate that cell death via apoptosis may be a mechanism of tumour reoxygenation during radiotherapy.

Severe anemia is associated with poor tumor oxygenation in head and neck squamous cell carcinomas

PURPOSE

To investigate the relationship between tumor oxygenation and the blood hemoglobin (Hb) concentration in patients with squamous cell carcinoma of the head and neck (SCCHN).

METHODS AND MATERIALS

A total of 133 patients with SCCHN underwent pretreatment polarographic pO2 measurements of their tumors. In 66 patients measurements were also made in sternocleidomastoid muscles. The patients were divided into three groups according to their Hb concentration-severe anemia (Hb < 11.0 g/dl), mild anemia (female: Hb 11.0-11.9 g/dl; male: Hb 11.0-12.9 g/dl), and normal Hb concentration (female: Hb > or =12.0 g/dl; male: > or =13.0 g/dl).

RESULTS

No significant difference in tumor oxygenation could be detected between mildly anemic patients and patients with a normal Hb level. However, the tumor oxygenation in the severely anemic group was significantly below that of each of the other two groups (p < 0.0001). There was no significant difference between the Hb groups in oxygenation of sternocleidomastoid muscles. In a multivariate analysis including Hb group, tumor volume, smoking habits, gender, T-stage, N-stage, and histologic grade a Hb level < 11 g/dl was found to be the strongest predictor for a poor tumor oxygenation. Smoking also had a marginal influence on median pO2.

CONCLUSION

Our data suggest that a low Hb concentration and cigarette smoking contribute to inadequate oxygenation of SCCHN and thus for increased radioresistance. Consequently, Hb correction and abstinence from smoking may significantly improve tumor oxygenation.

Intratumoral pO2-measurements as predictive assay in the treatment of carcinoma of the uterine cervix

BACKGROUND

Several studies have shown that pretreatment oxygenation status of cervical tumors measured with a polarographic oxygen electrode could be a predictive factor for radiation response and survival. The purpose of this study was to evaluate the impact of intratumoral pO2 levels and hypoxic fractions on local control and disease free survival employing a standardized measuring procedure under routine conditions.

MATERIALS AND METHODS

Between April 1994 and December 1997 pO2 measurements were performed prior to radiotherapy with an Eppendorf histograph in 51 evaluable patients with primary cervical carcinoma. All patients were treated with curative intent by combined external beam therapy (median total dose 49.6 Gy) and 3-6 applications of high dose rate- (7 Gy/fr. at point 'A') or pulse dose rate brachytherapy (20-25 h pulses, 1 Gy/pulse at point 'A'). Oxygenation data are given as median pO2 of pooled readings and percentage of readings below 5 mm Hg (HF 5).

RESULTS

Median pO2 values ranged from 0 to 60 mm Hg (median 10). HF5 ranged from 0 to 95% (median 22%). Median follow-up was 26 months (range 9-54 months). Actuarial overall and disease-free survival rates (OS/DFS) at 3 years were 53%/50%. Comparing patients with median pO2 < or = 10 mm Hg (n = 26) to patients with higher median pO2 levels (n = 25) calculated DFS was 34 and 69%, respectively (P < 0.02). Corresponding data for local control were 47 and 84% (P = 0.053). Comparing patients with HF5 below and above the median calculated DFS was 36 and 66%, respectively (P < 0.02). Patients who had median pO2 < 10 mm Hg and HF5 > 20% had the worst prognosis (3-year DFS: 28%). Besides oxygenation status, stage and initial hemoglobin concentration were statistically significant for treatment outcome.

CONCLUSIONS

This study confirms earlier data that the presence of hypoxia is associated with poor local control and survival in patients with carcinoma of the uterine cervix. Polarographic pO2 measurements are feasible under routine conditions and can be regarded as a reproducible predictive assay.

Changes in oxygenation during radiotherapy in carcinoma of the cervix

PURPOSE

The aim of this study was to investigate changes in tumor oxygenation, assessed by polarographic needle electrode measurements, following fractionated external beam radiotherapy in carcinoma of the cervix.

METHODS AND MATERIALS

Normal and tumor tissue oxygenation was measured in 19 patients prior to radiotherapy and after 40-45 Gy of external beam radiotherapy delivered in 20 fractions over 4 weeks. All measurements were performed during anesthesia.

RESULTS

There was no significant difference in the level of normal tissue oxygenation pre- and post radiotherapy. The individual patient median tumor pO2 values ranged from 0 to 31 mmHg pre-radiotherapy and 1 to 61 mmHg post-radiotherapy. The mean of the 19 median pO2 values increased from 8 (SD +/- 10) mmHg to 20 (+/- 20) mmHg following external beam radiotherapy. The increase was significant by paired Wilcoxon test (p = 0.011). There was also a significant fall in the proportion of values < 5 mmHg (p = 0.040). Although this value remained constant, or fell, in the majority of patients (15/19), it increased in 4 tumors. Tumor size pre- and postradiotherapy did not correlate with the level of pretreatment oxygenation; neither did the change in tumor size and change in level of oxygenation.

CONCLUSION

The level of tumor oxygenation increased in the majority of patients (15/19) following 40-45 Gy of radiotherapy in carcinoma of the cervix.

Influence of the hypoxic subvolume on the survival of patients with head and neck cancer

PURPOSE

Tumor hypoxia is regarded as an important factor influencing radiation response, disease-free, and overall survival of patients with squamous cell carcinoma of the head and neck (SCCHN). This study was performed to reevaluate the prognostic significance of the "classical oxygenation parameters" hypoxic fraction (percentage of pO2 values < 5 mmHg or < 2.5 mmHg, respectively) and median pO2, and to determine the influence of a new radiobiological factor. This factor was termed the "hypoxic subvolume" (HSV) and was defined as percentage of pO2-values below 5 mmHg multiplied by the total tumor volume. The rationale of this parameter was to quantify approximately the amount of hypoxic tissue which should be correlated to the number of hypoxic cells in the tumor. It is obvious that a tumor of 100 cm3 with a hypoxic fraction of 20% (HSV = 20 cm3) contains more hypoxic cells than a tumor of 1 cm3 with a hypoxic fraction of 50% (HSV = 0.5 cm3).

METHODS AND MATERIALS

Pretreatment pO2 was assessed in 59 patients with SCCHN with the Eppendorf histograph, and pretreatment volume was determined by ultrasonography (lymphnode metastases) and computer tomography (primaries). All patients were referred to our departments for radiotherapy (n = 27, median dose 70 Gy) or radiochemotherapy (n = 32; 5-FU, mitomycin C, median dose 70 Gy), respectively. All parameters were evaluated using the Kaplan-Meier analysis, and significance was assumed at a p-value of < 0.05 (log-rank test, Cox-Mantel). A multivariate analysis was performed to control for confounding factors. The median follow-up was 233 days. At the time of the evaluation, 34 of the 59 patients were dead.

RESULTS

In univariate analyses, the hypoxic fraction (pO2 < 5 mmHg, PO2 < 2.5 mmHg [p < 0.05]), the hemoglobin concentration (p < 0.05), and the hypoxic subvolume (p < 0.01) were of prognostic significance for overall survival. In multivariate analysis, the hemoglobin concentration and the hypoxic subvolume (p = 0.01) were significant prognosticators. We found no significant correlation between tumor volume or median pO2 and overall survival. No clear correlation was found between tumor volume and hypoxic fraction.

CONCLUSION

These data suggest that the total amount of hypoxic tissue, as determined by the hypoxic subvolume, influences the prognosis of patients suffering from SCCHN. In addition, our data confirm the statements of previous studies that low pretherapy pO2-values indicate a worse prognosis.

Blood flow and oxygenation status of human tumors. Clinical investigations

PURPOSE

There is a large body of evidence suggesting that blood flow and oxygenation of human tumors are important research topics which may explain, in particular, resistance to radiation and to many antineoplastic drugs, which can limit the curability of solid tumors by radiotherapy and chemotherapy.

MATERIALS AND METHODS

This manuscript reviews the clinical investigations which have been performed regarding blood flow and oxygenation status of human tumors in radiation oncology.

RESULTS

The possible uses and limitations of the prognostic significance and the changes under therapy measuring blood flow and oxygenation in human tumors were discussed. In addition, several approaches were summarized, which can improve the microvascular O2 availability and perfusion-limited O2 delivery.

CONCLUSION

The clinical data concerning the prognostic significance of blood flow, vascular function and oxygenation of human tumors are relevant for patient selection in clinical oncology. Strategies to improve traditional cancer therapy by modulation of the oxygenation status remain quite promising but more critical research and sophisticated clinical studies are necessary before its true potential is known.