Technology in cancer research & treatment
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Technol. Cancer Res. Treat. · Feb 2014
Using a novel dose QA tool to quantify the impact of systematic errors otherwise undetected by conventional QA methods: clinical head and neck case studies.
Recent studies have demonstrated that per-beam planar intensity-modulated radiation therapy (IMRT) quality assurance (QA) passing rates may not predict clinically relevant patient dose errors. This work is to evaluate the effect of dose variations introduced in dynamic multi-leaf collimator (DMLC) modeling and delivery processes on clinically relevant metrics for IMRT. Ten head and neck (HN) IMRT plans were randomly selected for this study. ⋯ However, in the two scenarios, a strong and clear correlation between the dose differences for each of the organ structures was observed. This study confirms that conventional IMRT QA performance metrics are not predictive of dose errors in PTV and organs-at-risk. The clinically-relevant-dose QA has allowed us to predict the patient dose-volume relationships.
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Technol. Cancer Res. Treat. · Jun 2013
Expression of M2-polarized macrophages is associated with poor prognosis for advanced epithelial ovarian cancer.
Macrophages are polarized into two functionally distinct forms, M1 and M2, in response to different microenvironment. Tumor-associated macrophages (TAMs) generally have M2 phenotype and promote tumor progression. Few studies to date have described the infiltration of M2-polarized macrophages in ovarian cancer. ⋯ Similarly, we also observed significantly improved 3-year PFS (49.8% vs. 11.0%, p < 0.001) and OS (77.4% vs. 45.0%, p < 0.001) rates in patients in the low-CD163/CD68 ratio group when compared with the high-CD163/CD68 ratio group. Multivariate analysis identified the density of CD163-positive cells as well as the ratio of CD163/CD68 as negative predictors for PFS and OS, respectively. Our results show that the infiltration of CD163-positive M2 macrophages as well as activation of macrophages towards the M2 phenotype may contribute to poor survival in advanced ovarian cancer.
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Technol. Cancer Res. Treat. · Jun 2013
A clinical study of shrinking field radiation therapy based on (18)F-FDG PET/CT for stage III non-small cell lung cancer.
The aim is to investigate the feasibility of shrinking field technique after 40 Gy for stage III non-small cell lung cancer (NSCLC) during radiation therapy. Eighty-seven consecutive patients treated with intensity-modulated radiation therapy or three-dimensional conformal radiation therapy were enrolled in this study. (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) scanning was performed prior to treatment and repeated after 40 Gy, and the delineation of target volume was based on fused images of PET and CT. After 40 Gy of conventional fractionated radiotherapy to the initial planning target volume (PTV), a boost of 19.6-39.2 Gy was delivered to the shrunken PTV through late course accelerated hyperfractionated radiotherapy, and the median total dose was 66.0 Gy (range, 59.6-79.2 Gy). ⋯ Numbers of patients who had outfield, infield and both infield and outfield recurrences were 3 (3.4%), 26 (29.5%), and 3 (3.4%), respectively. In conclusion, significant tumor regression was observed after 40 Gy, and radiation dose escalated after shrinking field with acceptable toxicity and outfield relapse. Shrinking field radiotherapy based on (18)F-FDG PET/CT after 40 Gy was safe and feasible for stage III NSCLC.
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Technol. Cancer Res. Treat. · Apr 2013
Comparative StudyA comparative analysis of radiobiological models for cell surviving fractions at high doses.
For many years the linear-quadratic (LQ) model has been widely used to describe the effects of total dose and dose per fraction at low-to-intermediate doses in conventional fractionated radiotherapy. Recent advances in stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) have increased the interest in finding a reliable cell survival model, which will be accurate at high doses, as well. Different models have been proposed for improving descriptions of high dose survival responses, such as the Universal Survival Curve (USC), the Kavanagh-Newman (KN) and several generalizations of the LQ model, e.g. the Linear-Quadratic-Linear (LQL) model and the Pade Linear Quadratic (PLQ) model. ⋯ This is an important improvement over the LQ model which predicts a Gaussian at high doses. Overall and for the highlighted reasons, it was concluded that the PLQ, USC and LQL models are theoretically well-founded. They could prove useful compared to the other proposed radiobiological models in clinical applications for obtaining uniformly accurate cell surviving fractions encountered in stereotactic high-dose radiotherapy as well as at medium and low doses.
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Technol. Cancer Res. Treat. · Aug 2012
Comparative StudyComparison of BOLD cerebrovascular reactivity mapping and DSC MR perfusion imaging for prediction of neurovascular uncoupling potential in brain tumors.
The coupling mechanism between neuronal firing and cerebrovascular dilatation can be significantly compromised in cerebral diseases, making it difficult to identify eloquent cortical areas near or within resectable lesions by using Blood Oxygen Level Dependent (BOLD) fMRI. Several metabolic and vascular factors have been considered to account for this lesion-induced neurovascular uncoupling (NVU), but no imaging gold standard exists currently for the detection of NVU. However, it is critical in clinical fMRI studies to evaluate the risk of NVU because the presence of NVU may result in false negative activation that may result in inadvertent resection of eloquent cortex, resulting in permanent postoperative neurologic deficits. ⋯ Our results demonstrate that while T2*MR perfusion maps and CVR maps are both adequate to map tumoral regions at risk of NVU in high grade gliomas, CVR maps can detect areas of decreased CVR also in low and intermediate grade gliomas where NVU may be caused by factors other than tumor neovascularity alone. Comparison of areas of abnormally decreased regional CVR with areas of absent BOLD task-based activation in expected eloquent cortical regions infiltrated by or adjacent to the tumors revealed overall 95% concordance, thus confirming the capability of BH CVR mapping to effectively demonstrate areas of NVU. ed by factors other than tumor neovascularity alone. Comparison of areas of abnormally decreased regional CVR with areas of absent BOLD task-based activation in expected eloquent cortical regions infiltrated by or adjacent to the tumors revealed overall 95% concordance, thus confirming the capability of BH CVR mapping to effectively demonstrate areas of NVU.