Search results for "Tumor Oxygenation"

Modulating tumor hypoxia by nanomedicine for effective cancer therapy

2016

Hypoxia, a characteristic feature of tumors, is indispensable to tumor angiogenesis, metastasis, and multi drug resistance. Hypoxic avascular regions, deeply embedded inside the tumors significantly hinder delivery of therapeutic agents. The low oxygen tension results in resistance to the current applied anti-cancer therapeutics including radiotherapy, chemotherapy, and photodynamic therapy, the efficacy of which is firmly tied to the level of tumor oxygen supply. However, emerging data indicate that nanocarriers/nanodrugs can offer substantial benefits to improve the efficacy of current therapeutics, through modulation of tumor hypoxia. This review aims to introduce the most recent advance…

Changes in Perfusion Pattern of Experimental Tumors Due to Reduction in Arterial Oxygen Partial Pressure

2006

Tumor hypoxia in pelvic recurrences of cervical cancer.

1998

We have previously demonstrated in primary cancer of the uterine cervix that tumor hypoxia, as determined polarographically, is strongly associated with clinical malignant progression of the disease. Having applied a similar methodological approach to investigate loco-regional relapses, we found a pronounced shift to more hypoxic oxygenation profiles in the recurrent tumors than in the primary tumors. Median pO2 values in 53 pelvic recurrences were significantly lower than the median pO2 values of 117 primary tumors of comparable sizes (7.1 +/- 1.1 mmHg vs. 12.1 +/- 1.0 mmHg, p = 0.0013). The differences in tumor oxygenation between primary and recurrent tumors mirrored the differences in t…

Tumor oxygenation: a new predictive parameter in locally advanced cancer of the uterine cervix.

1993

Abstract Experimental evidence suggests that hypoxia may increase the malignant potential and reduce the sensitivity toward nonsurgical treatment modalities in solid rodent tumors. However, the importance of tumor hypoxia in human malignancies is still uncertain. We have developed a clinically applicable standardized procedure for the determination of intratumoral p O 2 in advanced cervical cancers by use of a computerized polarographic needle electrode histograph. To evaluate the significance of tumor oxygenation as a new oncologic parameter we initiated an open prospective clinical trial at the University of Mainz Medical Center in June 1989. Until October 1992 50 patients with advanced c…

Oxygenation Status of Gynecologic Tumors: What is the Optimal Hemoglobin Level?

2002

Tumor hypoxia has been linked to the development of treatment resistance, tumor progression, and poor prognosis. Since anemia is a major causative factor for the development of hypoxia, the association between blood hemoglobin concentration (cHb) and tumor oxygenation was examined in this study.Pretreatment O(2) tension (pO(2)) measurements were performed in 59 primary carcinomas of the uterine cervix in which a stringent histopathologic examination of the electrode tracks was mandatory in order to exclude measurements in necrotic, stromal or normal cervical tissue. In addition, pO(2) readings in twelve primary cancers and 17 local recurrences of vulvar cancers were included in this study. …

Tumor Hypoxia: Causative Factors, Compensatory Mechanisms, and Cellular Response

2004

Abstract Learning Objectives After completing this course, the reader will be able to: Explain the effect of hypoxia on resistance to treatment. Describe the causes of tumor hypoxia. Characterize cellular response to hypoxia. Access and take the CME test online and receive 1 hour of AMA PRA category 1 credit at CME.TheOncologist.com Hypoxia is a characteristic feature of locally advanced solid tumors resulting from an imbalance between oxygen (O2) supply and consumption. Major causative factors of tumor hypoxia are abnormal structure and function of the microvessels supplying the tumor, increased diffusion distances between the nutritive blood vessels and the tumor cells, and reduced O2 tra…

Treatment Resistance of Solid Tumors

2001

Hypoxia is a characteristic property of locally advanced solid tumors, resulting from an imbalance between the supply and consumption of oxygen. Major pathogenetic mechanisms for the development of hypoxia are (1) structural and functional abnormalities of the tumor microvasculature, (2) increased diffusion distances, and (3) tumor-associated and therapy-induced anemia. The oxygenation status is independent of clinical tumor size, stage, grade, and histopathological type, but is affected by the hemoglobin level. Hypoxia is intensified in anemic patients, especially in tumors with low perfusion rates. Hypoxia and anemia (most probably via worsening of tumor hypoxia) can lead to therapeutic p…

Modulation of tumor oxygenation

1998

There is a large body of evidence suggesting that deficiencies in the O2 supply of tumors exist due to restrictions (i) in the O2 delivery by perfusion and/or diffusion, and (ii) in the O2 transport capacity. Whereas the former are mostly based on inadequate and heterogeneous microcirculatory functions, the latter are predominantly due to tumor-associated anemia. Possible uses and limitations of measures are discussed which can increase the microvascular O2 content and thus may preferentially serve to enhance diffusion-limited O2 availability. In addition, means are described for improving and increasing the uniformity of microcirculation thus possibly enhancing perfusion-limited O2 deliver…

O2 extraction is a key parameter determining the oxygenation status of malignant tumors and normal tissues

2003

The aim of this study was to assess pivotal factors determining the oxygenation status of malignant tumors, and, for comparison, of normal tissues. For this purpose, microvascular patterns, blood flow data, O2 consumption rates and O2 extractions were correlated to the median pO2 values of isografted rodent and xenografted human tumors, and of various normal tissues. No correlations were found between median pO2 values and vascular patterns, O2 consumption rate or blood flow rate. When O2 extraction, however, was considered (a comprehensive parameter which encompasses all of the above factors), a strong inverse correlation was found between this parameter and the median pO2 values, both for…

Hypoxia and radiation response in human tumors

1996

This study demonstrates by an updated analysis of an ongoing prospective study that tumor oxygenation, as measured with a validated standardized polarographic needle electrode method before treatment, powerfully predicts the prognosis of patients receiving radiotherapy for intermediate and advanced stage cancer of the uterine cervix. First evidence for a host component in tumor oxygenation based on a significant correlation between median pO 2 values determined in normal subcutaneous fatty tissue and in cervical cancer is also presented. Further investigations are necessary to clarify whether tumor hypoxia is just a marker of intrinsic tumor aggressiveness or whether the negative impact of …