Associations between tumor vascularization assessed by in vivo DCE-MRI and the presence of disseminated tumor cells in bone marrow in breast cancer patients at the time of diagnosis.

PURPOSE: To explore possible associations between in vivo pharmacokinetic dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters and the presence of disseminated tumor cells (DTCs) in bone marrow in breast cancer patients at the time of diagnosis. MATERIALS AND METHODS: Thirty-seven women with breast cancer (stage T2-4N0-1M0) were included. Patients were classified as DTC+ if one or more DTCs were detected by immunocytochemistry. DCE-MRI was acquired with a radial 3D T1 -weighted spoiled gradient echo sequence with k-space weighted image contrast. K(trans), kep, and ve were calculated using the extended Tofts model and a population-derived arterial input function. The nonparametric Mann-Whitney U-test was used to compare the histogram distributions of the pharmacokinetic parameters for the DTC+ and the DTC- patients. RESULTS: DTCs were detected in 7 of the 37 patients (19%). In DTC+ patients, the distribution of tumor K(trans) and kep were significantly (P < 0.01) more shifted towards lower values than in DTC- patients. CONCLUSION: An association between vascular dependent pharmacokinetic DCE-MRI parameters and the presence of DTCs were found. Compared to DTC- patients, DTC+ patients had poorer perfusion and permeability, indicative of hypoxia. Thus, pharmacokinetic parameters might be surrogate biomarkers of metastatic potential and future relapse.

The clinical impact of mean vessel size and solidity in breast carcinoma patients.

Angiogenesis quantification, through vessel counting or area estimation in the most vascular part of the tumour, has been found to be of prognostic value across a range of carcinomas, breast cancer included. We have applied computer image analysis to quantify vascular properties pertaining to size, shape and spatial distributions in photographed fields of CD34 stained sections. Aided by a pilot (98 cases), seven parameters were selected and validated on a separate set from 293 breast cancer patients. Two new prognostic markers were identified through continuous cox regression with endpoints breast cancer specific survival and distant disease free survival: The average size of the vessels as measured by their perimeter (p = 0.003 and 0.004, respectively), and the average complexity of the vessel shapes measured by their solidity (p = 0.004 and 0.004). The Hazard ratios for the corresponding median-dichotomized markers were 2.28 (p = 0.005) and 1.89 (p = 0.016) for the mean perimeter and 1.80 (p = 0.041) and 1.55 (p = 0.095) for the shape complexity. The markers were associated with poor histologic type, high grade, necrosis, HR negativity, inflammation, and p53 expression (vessel size only). Both markers were found to strongly influence the prognostic properties of vascular invasion (VI) and disseminated tumour cells in the bone marrow. The latter being prognostic only in cases with large vessels (p = 0.004 and 0.043) or low complexity (p = 0.018 and 0.024), but not in the small or complex vessel groups (p>0.47). VI was significant in all groups, but showed greater hazard ratios for small and low complexity vessels (6.54-11.2) versus large and high complexity vessels (2.64-3.06). We find that not only the overall amount of produced vasculature in angiogenic hot-spots is of prognostic significance, but also the morphological appearance of the generated vessels, i.e. the size and shape of vessels in the studied hot spots.

Hypoxic tumor kinase signaling mediated by STAT5A in development of castration-resistant prostate cancer.

In this study, we hypothesized that androgen-deprivation therapy (ADT) in prostate cancer, although initially efficient, induces changes in the tumor kinome, which subsequently promote development of castration-resistant (CR) disease. Recognizing the correlation between tumor hypoxia and poor prognosis in prostate cancer, we further hypothesized that such changes might be influenced by hypoxia. Microarrays with 144 kinase peptide substrates were applied to analyze CWR22 prostate carcinoma xenograft samples from ADT-naïve, androgen-deprived (AD), long-term AD (ADL), and CR disease stages. The impact of hypoxia was assessed by matching the xenograft kinase activity profiles with those acquired from hypoxic and normoxic prostate carcinoma cell cultures, whereas the clinical relevance was evaluated by analyzing prostatectomy tumor samples from patients with locally advanced disease, either in ADT-naïve or early CR disease stages. By using this novel peptide substrate microarray method we revealed high kinase activity mediated by signal transducer and activator of transcription 5A (STAT5A) in CR prostate cancer. Additionally, we uncovered high STAT5A kinase activity already in regressing ADL xenografts, before renewed CR growth was evidenced. Finally, since increased STAT5A kinase activity also was detected after exposing prostate carcinoma cells to hypoxia, we propose long-term ADT to induce tumor hypoxia and stimulate STAT5A kinase activity, subsequently leading to renewed CR tumor growth. Hence, the study detected STAT5A as a candidate to be further investigated for its potential as marker of advanced prostate cancer and as possible therapeutic target protein.

Routine pelvic MRI using phased-array coil for detection of extraprostatic tumour extension: accuracy and clinical significance.

OBJECTIVES: To determine the accuracy and assess the clinical significance of surface-coil 1.5-T magnetic resonance imaging (MRI) for the detection of locally advanced prostate cancer (PCa). METHODS: Between December 2007 and January 2010, we examined 209 PCa patients (mean age = 62.5 years) who were consecutively treated with robot-assisted laparoscopic prostatectomy and prospectively staged by MRI. One hundred and thirty-five patients (64.6 %) had locally advanced disease. Conventional clinical tumour stage and MRI-assessed tumour stage were compared with histopathological tumour stage (pT). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall accuracy (OA) were calculated using pT as the "gold standard". Overstaged and understaged cases at MRI were reviewed. RESULTS: Sensitivity, specificity, PPV, NPV and OA for the detection of locally advanced disease were 25.9, 95.9, 92.1, 41.2 and 50.5 % and 56.3, 82.2, 85.4, 50.4 and 65.4 % for clinical staging and MRI, respectively. Among patients understaged at MRI, the resection margins were free in 64.4 % of the cases (38/59). CONCLUSIONS: Although the accuracy was limited, the detection of locally advanced disease improved substantially when MRI was added to routine clinical staging. The majority of the understaged patients nevertheless achieved free margins. When assessing the clinical significance of MRI staging the extent of extraprostatic extension has to be considered.

Assessment of liposome biodistribution by non-invasive optical imaging: a feasibility study in tumour-bearing mice.

Liposomal encapsulation of cytostatics improves drug delivery to tumour tissue and reduces dose-limiting systemic toxicities. Development and evaluation of new liposome formulations is time consuming and costly with high demands for experimental animals. A faster and less demanding means of comparing several product candidates may be provided by use of non-invasive methods for assessing pharmacokinetics and biodistribution. In this study we have evaluated the feasibility of using small animal fluorescence optical imaging as a strategy to study liposome accumulation in tumours. Liposomal doxorubicin (Caelyx) was labelled with a lipophilic carbocyanine tracer and administered to tumour-bearing mice. Subsequently, the in vivo distribution of the labelled liposomes was followed over time by fluorescent optical imaging. The results revealed a gradual increase in tumour fluorescence, indicating accumulation of the liposomes reaching plateau levels at 48 h post injection. However, due to loss of dye from liposomes during circulation combined with substantial scattering and absorption of in vivo fluorescent signal, reliable quantitative correlation between the biodistribution profile of the labelled liposomes and doxorubicin could not be obtained.

The updated ESTRO core curricula 2011 for clinicians, medical physicists and RTTs in radiotherapy/radiation oncology.

INTRODUCTION: In 2007 ESTRO proposed a revision and harmonisation of the core curricula for radiation oncologists, medical physicists and RTTs to encourage harmonised education programmes for the professional disciplines, to facilitate mobility between EU member states, to reflect the rapid development of the professions and to secure the best evidence-based education across Europe. MATERIAL AND METHODS: Working parties for each core curriculum were established and included a broad representation with geographic spread and different experience with education from the ESTRO Educational Committee, local representatives appointed by the National Societies and support from ESTRO staff. RESULTS: The revised curricula have been presented for the ESTRO community and endorsement is ongoing. All three curricula have been changed to competency based education and training, teaching methodology and assessment and include the recent introduction of the new dose planning and delivery techniques and the integration of drugs and radiation. The curricula can be downloaded at http://www.estro-education.org/europeantraining/Pages/EuropeanCurricula.aspx. CONCLUSION: The main objective of the ESTRO core curricula is to update and harmonise training of the radiation oncologists, medical physicists and RTTs in Europe. It is recommended that the authorities in charge of the respective training programmes throughout Europe harmonise their own curricula according to the common framework.

Iterative reconstruction reduces abdominal CT dose.

OBJECTIVE: In medical imaging, lowering radiation dose from computed tomography scanning, without reducing diagnostic performance is a desired achievement. Iterative image reconstruction may be one tool to achieve dose reduction. This study reports the diagnostic performance using a blending of 50% statistical iterative reconstruction (ASIR) and filtered back projection reconstruction (FBP) compared to standard FBP image reconstruction at different dose levels for liver phantom examinations. METHODS: An anthropomorphic liver phantom was scanned at 250, 185, 155, 140, 120 and 100 mAs, on a 64-slice GE Lightspeed VCT scanner. All scans were reconstructed with ASIR and FBP. Four readers evaluated independently on a 5-point scale 21 images, each containing 32 test sectors. In total 672 areas were assessed. ROC analysis was used to evaluate the differences. RESULTS: There was a difference in AUC between the 250 mAs FBP images and the 120 and 100 mAs FBP images. ASIR reconstruction gave a significantly higher diagnostic performance compared to standard reconstruction at 100 mAs. CONCLUSION: A blending of 50-90% ASIR and FBP may improve image quality of low dose CT examinations of the liver, and thus give a potential for reducing radiation dose.

Low dose hyper-radiosensitivity is eliminated during exposure to cycling hypoxia but returns after reoxygenation.

PURPOSE: To investigate the effect of cycling hypoxia on low dose hyper-radiosensitivity (HRS). MATERIALS AND METHODS: Human breast tumor T-47D cells were grown in a hypoxia workstation operated at 4% O(2) for 3-6 weeks and the pericellular oxygen concentration was recorded every 20 minutes. The presence of HRS in response to subsequent challenge irradiation was measured by clonogenic survival. RESULTS: T-47D cells adapted to growing with 4% O(2) in the gas phase but showed no HRS. However, HRS was recovered after between 48 h and two weeks of reoxygenation at 20% O(2). Medium transferred from the hypoxic T-47D cells removed HRS in recipient cells grown in ambient air. Cells irradiated with X-rays showed a shallower HRS-'dip' and a lower d(c)-value (dose where the change from the hypersensitive to the induced repair response is 63% complete) compared to cells irradiated with (60)Co γ-rays. CONCLUSIONS: Cycling hypoxia transiently eliminates HRS in T-47D cells in vitro. This may partly explain the diverging results of in vivo studies of HRS. The effect of cycling hypoxia on HRS is comparable to our previous findings for T-47D cells receiving medium transfer from cells irradiated with 0.3 Gy at 0.3 Gy/h.

Quantification of angiogenesis in breast cancer by automated vessel identification in CD34 immunohistochemical sections.

BACKGROUND/AIM: Tumor growth is dependent upon angiogenesis. Tumor vascularity, as measured by microvessel density or Chalkley counts, has been shown to predict treatment outcome. However, many issues related to reproducibility and methodology have prevented its clinical application. We present a method of automatic vessel identification applied to CD34 immunohistochemical sections which facilitates increased reproducibility. MATERIALS AND METHODS: Pixel colour information was used to identify CD34 stain. In order to reduce the effects of noise and background, stained areas smaller than 3.5 µm were ignored. RESULTS: Comparing automatic and manual vessel counts in 50 randomly selected breast cancer cases, the method achieved an intraclass correlation coefficient of r(a)(2)=0.96 and a 95% confidence interval for the percentage difference between the counts from -26.1% to 10.8%. The method was also found to have a sensitivity approaching 100%. CONCLUSION: The method can reliably be used on colour photographs of staining for CD34 to quantify angiogenesis.

Ultrasound enhanced antitumor activity of liposomal doxorubicin in mice.

Liposomal encapsulation of doxorubicin (DXR) improves tumor accumulation and reduces adverse effects. One possible strategy for further optimization of this delivery technology would be to design the liposome carrier to release its content within the tumor tissue in response to specific stimuli such as ultrasound (US). In this study, the tumor uptake properties and therapeutic efficacy of 1,2 distearoyl-sn-glycero-3-phosphatidylethanolamine-based liposomes containing DXR were investigated in nude mice bearing tumor xenografts. The liposomal DXR formulation alone showed no inhibitory effect on tumor growth. However, upon exposure to low frequency US in situ inhibition of tumor growth was demonstrated.

Dose evaluation and risk estimation for secondary cancer in contralateral breast and a study of correlation between thorax shape and dose to organs at risk following tangentially breast irradiation during deep inspiration breath-hold and free breathing.

PURPOSE: To assess the impact of using breathing adapted radiotherapy on contralateral breast (CB) dose, to relate the thorax shape with the dose to the organs at risk (OARs) and to predict the risk for induced malignancies in CB using linear and non-linear models, following tangential irradiation of breast. MATERIAL AND METHODS: Sixteen patients with stage I-II breast cancer treatment planned with tangential fields using deep inspiration breath hold (DIBH) and free breathing (FB) techniques were included in this analysis. The dose results mainly based on DVH analysis were compared. Four parameters were defined to describe thoracic shape. Excess relative risk (ERR) for cancer induction in CB, employing linear and non-linear models was calculated. RESULTS: Average CB volumes exposed to a dose of 1 Gy is 1.3 times higher in DIBH plans than in FB plans. No significant difference in average V3Gy and V5Gy for DIBH and FB plans is observed. The average mean CB dose for DIBH and FB plans is 0.33 and 0.28 Gy, respectively. No correlation between thorax shape parameters and mean OARs dose is observed. The estimated average mean ERR with linear model is lower in FB plans (0.12) than for the DIBH plans (0.14). The estimated ERR with non-linear model is 0.14 for DIBH plans and 0.15 for FB plans. CONCLUSION: No significant difference in CB dose between DIBH and FB plans is observed. The four thorax shape parameters defined in this study can not be related to the dose at OARs using DIBH and FB radiation techniques. The ERR estimates for secondary CB cancer are nearly the same for FB and DIBH planning when using a linear and non-linear risk prediction models.

Longitudinal magnetic resonance imaging-based assessment of vascular changes and radiation response in androgen-sensitive prostate carcinoma xenografts under androgen-exposed and androgen-deprived conditions.

Prostate cancer (PCa) patients receive androgen-deprivation therapy (ADT) to reduce tumor burden. However, complete eradication of PCa is unusual, and recurrent disease is evident within approximately 2 years in high-risk patients. Clinical evidence suggests that combining ADT with radiotherapy improves local control and disease-free survival in these patients compared with radiotherapy alone. We investigated whether vascularization of androgen-sensitive PCa xenografts changed after ADT and whether such therapy affected radiation response. CWR22 xenografts received combinations of ADT by castration (CWR22-cas) and 15 Gy of single-dose irradiation. At a shortest tumor diameter of 8 mm, vascularization was visualized by dynamic contrast-enhanced magnetic resonance imaging before radiation and 1 and 9 days after radiation. Voxel-wise quantitative modeling of contrast enhancement curves extracted the hemodynamic parameter K(trans), reflecting a combination of permeability, density, and blood flow. Tumor volumes and prostate-specific antigen (PSA) were monitored during the experiment. The results showed that K(trans) of CWR22-cas tumors 36±4 days after ADT was 47.1% higher than K(trans) of CWR22 tumors (P = .01). CWR22-cas tumors showed no significant changes in K(trans) after radiation, whereas K(trans) of CWR22 tumors at day 1 decreased compared with pretreatment values (P = .04) before a continuous increase from day 1 to day 9 followed (P = .01). Total PSA in blood correlated positively to tumor volume (r = 0.59, P < .01). In conclusion, androgen-exposed xenografts demonstrated radiation-induced reductions in vascularization and tumor volumes, whereas androgen-deprived xenografts showed increased vascularization and growth inhibition, but no significant additive effect of radiation.

Improved image quality of low-dose thoracic CT examinations with a new postprocessing software.

In 2008 a phantom study indicated that there is a potential for reducing the CT doses when using a new postprocessing filter. The purpose of this study was to test this new postprocessing filter clinically for low-dose chest CT examinations, to assess whether the diagnostic performance is the same or improved. A standardized clinical chest CT protocol was used on patients with colorectal cancer. Only mA settings changed between patients according to patient size. One standard and one low-dose chest protocol were performed for all patients. The low-dose images were postprocessed with a new software filter, which provides context-controlled restoration of digital images by using adaptive filters. Three radiologists assessed randomly all the images independently. A total of 24 scan series were evaluated with respect to image quality according to quality criteria from the European guidelines for chest CT using a five-point scale; 576 details were assessed. Overall mean score is the average score for all details rated for all three readers for all full-dose series, low-dose series and low-dose enhanced series, respectively. The statistical methods used for comparison were paired sampled t-test and intraclass correlation coefficient. The postprocessing filter improved the diagnostic performance compared to the unenhanced low-dose images. Mean score for full-dose, low-dose and low-dose enhanced series were 3.8, 3.0 and 3.3, respectively. For all patients the full-dose series gave higher scores than the low-dose series. Intraclass correlation coefficients were 0.2, 0.1 and 0.3 for the full-dose, low-dose and low-dose enhanced series, respectively. There is a potential for improving diagnostic performance of low-dose CT chest examinations using this new postprocessing filter.

Diffusion-weighted magnetic resonance imaging for pretreatment prediction and monitoring of treatment response of patients with locally advanced breast cancer undergoing neoadjuvant chemotherapy.

BACKGROUND: For patients with locally advanced breast cancer (LABC) undergoing neoadjuvant chemotherapy (NACT), the European Guidelines for Breast Imaging recommends magnetic resonance imaging (MRI) to be performed before start of NACT, when half of the NACT has been administered and prior to surgery. This is the first study addressing the value of flow-insensitive apparent diffusion coefficients (ADCs) obtained from diffusion-weighted (DW) MRI at the recommended time points for pretreatment prediction and monitoring of treatment response. MATERIALS AND METHODS: Twenty-five LABC patients were included in this prospective study. DW MRI was performed using single-shot spin-echo echo-planar imaging with b-values of 100, 250 and 800 s/mm(2) prior to NACT, after four cycles of NACT and at the conclusion of therapy using a 1.5 T MR scanner. ADC in the breast tumor was calculated from each assessment. The strength of correlation between pretreatment ADC, ADC changes and tumor volume changes were examined using Spearman's rho correlation test. RESULTS: Mean pretreatment ADC was 1.11 + or - 0.21 x 10(-3) mm(2)/s. After 4 cycles of NACT, ADC was significantly increased (1.39 + or - 0.36 x 10(-3) mm(2)/s; p=0.018). There was no correlation between individual pretreatment breast tumor ADC and MR response measured after four cycles of NACT (p=0.816) or prior to surgery (p=0.620). CONCLUSION: Pretreatment tumor ADC does not predict treatment response for patients with LABC undergoing NACT. Furthermore, ADC increase observed mid-way in the course of NACT does not correlate with tumor volume changes.

Adapting biological feedback in radiotherapy.

Recently, there has been much interest in how to use information on patient-specific tumor biology and normal tissue function to individualize cancer treatment. In radiation therapy, dose may be escalated to radioresistant regions within a tumor, or regions of particular functional importance in normal organs may be preferentially spared. However, tumor and normal tissue biology may change during treatment, and adaptation of therapy may be necessary to ensure that optimal therapy is delivered. Furthermore, changes in tumor and normal tissue biology during early treatment may be predictive for the outcome of radiotherapy, and this information could be used for individual adaptation of the remaining part of the treatment. In the present study, we address variations that may occur in tumor and normal tissue radiobiological properties during radiotherapy, and how these may be related to the response to treatment. Moreover, we discuss the criteria for when to adapt treatment and how this adaptation should be performed. Finally, we discuss to what degree biologically adapted radiotherapy may be expected to improve treatment outcome and which issues need to be resolved for this strategy to reach its full potential.

Optimal use of AEC in CT: a literature review.

BACKGROUND: Computed tomography (CT) examinations account for a significant portion of individuals' increasing exposure to medical radiation. Automatic exposure control (AEC) was introduced in CT scanners to decrease patient doses while maintaining appropriate image quality. OBJECTIVE: To identify areas for AEC optimization and suggest practical optimization methods. METHODS: A literature review was conducted to assess current knowledge regarding tube current modulation and AEC in CT from peer-reviewed journals and publications from national and international organizations involved in medical imaging and radiation protection. RESULTS: Four important aspects of AEC use were identified: interaction of user-selectable parameters with AEC, patient positioning and AEC, specific challenges with patient size groups and how to select appropriate input value. CONCLUSION: AEC is a useful tool for dose optimization but dose savings are not guaranteed unless the equipment is used properly. Further research is required into optimal use of AEC, particularly for pediatric examinations.

Late effects after radiotherapy for locally advanced cervical cancer: comparison of two brachytherapy schedules and effect of dose delivered weekly.

PURPOSE: To compare the severe late effects (Grade 3 or greater) for two groups of cervical cancer patients treated with the same external beam radiotherapy and two high-dose-rate intracavitary brachytherapy regimens and to investigate the influence of the dose delivered each week. METHODS AND MATERIALS: For 120 patients, intracavitary brachytherapy was delivered with 33.6 Gy in eight fractions to Point A (HD group), and for 119, intracavitary brachytherapy was delivered with 29.4 Gy in seven fractions to Point A (LD group). The cumulative incidence of severe gastrointestinal and genitourinary late effects were calculated for both dose groups using Kaplan-Meier survival analysis. This method was also used to explore whether the number of weeks with different dose levels could predict the cumulative incidence of late effects. RESULTS: The actuarial rate of developing severe gastrointestinal morbidity at 7 years was 10.7% and 8.3% for HD and LD groups, respectively. The rate for genitourinary morbidity was 6.6% for the HD group and 5.0% for the LD group, respectively. No significant difference was found between the two groups. The analyses showed that a marginally significant increase occurred in severe gastrointestinal complications as the number of weeks with a physical dose >20 Gy increased in the HD group (p = .047). CONCLUSION: To establish dose-response relationships for late complications, three-dimensional imaging and dose-volume histogram parameters are needed. We found some indications that 20 Gy/wk is an upper tolerance level when the dose to the International Commission on Radiation Units and Measurements rectum point is 81 Gy(alpha/beta=3) (isoeffective [equivalent] dose of 2-Gy fractions). However, additional investigations using three-dimensional data are needed.

Mechanisms of the elimination of low dose hyper-radiosensitivity in T-47D cells by low dose-rate priming.

PURPOSE: To investigate the mechanisms of elimination of low-dose hyper-radiosensitivity (HRS) in T-47D cells induced by 0.3 Gy low dose-rate (LDR) priming. MATERIALS AND METHODS: The mitotic ratio was measured using mitotic marker histone H3 phosphorylation in LDR primed as well as untreated T-47D cells. The HRS response in unprimed cells receiving medium which was irradiated after being harvested from unprimed cells was measured with or without serum present during cell conditioning. 4,6-benzylidene-D-glucose (BG) was used to inhibit protein synthesis during LDR priming. RESULTS: LDR primed T-47D cells were HRS-deficient and showed a decrease in mitotic ratio with increasing dose while unprimed, i.e., HRS-competent T-47D cells, showed no decrease in mitotic ratio for doses in the HRS-range. HRS was eliminated in LDR primed cells, in cells receiving medium transfer from LDR primed cells, and in cells receiving LDR irradiated medium harvested from unprimed cells. The efficacy of the transferred medium depended on the presence of serum during cell conditioning. LDR priming eliminated HRS even in the presence of protein synthesis inhibitor BG. CONCLUSIONS: LDR priming of T-47D cells as well as LDR priming of medium conditioned on T-47D cells induce a factor in the medium which cause the early G(2)-checkpoint to be activated in recipient cells by doses normally in the HRS dose-range.