Biomedical subjects

Susanne Briest

Publications and source records attributed to Susanne Briest.

4 recordsLinked to original sources

PubMed2005

Hypoxia in breast cancer: role of blood flow, oxygen diffusion distances, and anemia in the development of oxygen depletion.

Heterogeneously distributed hypoxic areas are a characteristic property of locally advanced breast cancers. Hypoxia results from an imbalance between the supply and consumption of oxygen (O2). Major pathogenetic mechanisms for the emergence of hypoxia are (i) structural and functional abnormalities in the tumor microvasculature, (ii) an adverse diffusion geometry, and (iii) tumor-related and therapy-induced anemia leading to a reduced O2 transport capacity of the blood. There is pronounced intertumor variability in the extent of hypoxia, which is independent of clinical size, stage, histology and grade. Hypoxia is intensified in anemic patients, especially in tumor (areas) with low perfusion rates. Tumor hypoxia is a therapeutic problem since it makes solid tumors resistant to sparsely ionizing radiation, some forms of chemotherapy, and photodynamic therapy. However, besides more direct mechanisms involved in the development of therapeutic resistance, there are, in addition, indirect machineries that can cause barriers to therapies. These include hypoxia-mediated alterations in gene expression, proteomic and genomic changes, and clonal selection. These in turn can drive subsequent events that are known to further increase resistance to therapy in addition to critically affecting long-term prognosis.

Anemia↗

PubMed2005

Breast cancer detection based on incremental biochemical and physiological properties of breast cancers: a six-year, two-site study.

RATIONALE AND OBJECTIVES: To demonstrate that near-infrared spectroscopy would achieve sufficient sensitivity and specificity in human breast cancer to reach ROC/AUC values in the 90s and yet to warn of the potential liabilities of introduction of a novel technology in this field. MATERIALS AND METHODS: 116 subjects from two nations (44 were cancer-verified by biopsy and histopathology) were reviewed. NIR spectroscopy of total hemoglobin and its relative oxygenation were monitored in breast cancers and compared to their contralateral breast in a 2D nomogram for diagnostic evaluation. A novel handheld NIR breast cancer detector pad with a 3-wavelength LED and 8 detectors with 4 cm separation between source and detectors was placed on the subject's breast. The method is convenient, rapid, and safe and has achieved high patient compliance with minimal patient apprehension of compression, confinement, or radioactivity. RESULTS: The absorbance increments of the cancerous region are referred to the mirror image location on the contralateral breast. The two metrics are increased hemoglobin concentration due to angiogenesis and decreased hemoglobin saturation due to hypermetabolism of the cancer. The 2D nomogram display of these two metrics shows Zone 1 contains verified cancers and Zone 2 contains noncancers. ROC evaluation of the nomogram gives 95% AUC for the two sites, Philadelphia and Leipzig. CONCLUSION: A simple, economical breast cancer detector has achieved high patient compliance and a high ROC/AUC score for a population which involved a range of tumors down to and including those of 0.8-1 cm in diameter.

Area Under Curve↗

PubMed2003

Oxygenation gain factor: a novel parameter characterizing the association between hemoglobin level and the oxygenation status of breast cancers.

Tumor hypoxia has been linked to acquired treatment resistance, tumor progression, and poor prognosis. Because anemia is a major causative factor for the development of hypoxia, the association between blood hemoglobin concentration (cHb) and breast cancer oxygenation was examined in this study. In addition, a novel parameter characterizing the relationship between oxygenation status and rising cHb is introduced: the oxygenation gain factor (OGF). In breast cancer patients, median cHb over the range 8.5-14.7 g/dl correlated positively with the median pO(2) (3-15 mm Hg), yielding an average OGF of 2 mm Hg.dl/g. In contrast, in normal tissues (normal breast, subcutis, and skeletal muscle) the median pO(2) values were substantially higher (52 mm Hg, 51 mm Hg, and 37 mm Hg, respectively) and remained constant irrespective of the hemoglobin level over the range from 10 to 16 g/dl (OGF = 0 in grade I anemia and nonanemic patients). Moderately lower median pO(2) values in subcutis and skeletal muscle were only observed in grade II anemia (8 g/dl < cHb < or =10 g/dl), although this would appear to be of no biological relevance. Conversely, in breast cancers, even mild anemia (grade I anemia) is a major causative factor for the development of hypoxia or anoxia.

Adult↗

PubMed2002

Hypoxia in breast cancer: pathogenesis, characterization and biological/therapeutic implications.

Nearly 50% of locally advanced breast cancers exhibit hypoxic and/or anoxic tissue areas that are heterogeneously distributed within the tumour mass. Hypoxia is predominantly caused by structural and functional abnormalities of the newly formed tumour vessels arising from neovascularization, by a disturbed microcirculation, by enlarged diffusion distances, and by tumour-associated or therapy-induced anaemia. The extent of pretherapeutically measured hypoxic tissue areas is independent of clinical tumour size and stage, and histological type and grade. Anaemia can substantially worsen tumour O2 depletion. Hypoxia is known to directly or indirectly confer resistance to irradiation and some chemotherapeutic drugs leading to treatment failure. Sustained tumour hypoxia also gives rise to a more malignant phenotype (malignant progression). Due to this association between tumour hypoxia, malignant progression and treatment failure, tumour oxygenation has proven to be an independent, powerful prognostic factor for local control, overall and disease-free survival. Pretreatment assessment of tumour hypoxia is therefore needed to allow the selection of patients for more aggressive treatment within clinical trials or for individualization of therapy, and to identify patients who could benefit from hypoxiatargeting treatment measures. Due to a relatively high risk of relapse, patients with hypoxic tumours should undergo close surveillance. Anaemia in cancer patients should be prevented/corrected in order to improve radio-/chemosensitivity and thus to increase cancer cure rates.

Breast Neoplasms↗