Tumor Oxygenation

About: Tumor Oxygenation is a research topic. Over the lifetime, 866 publications have been published within this topic receiving 52555 citations.

Hypoxia in cancer: significance and impact on clinical outcome

Abstract: Hypoxia, a characteristic feature of locally advanced solid tumors, has emerged as a pivotal factor of the tumor (patho-)physiome since it can promote tumor progression and resistance to therapy. Hypoxia represents a “Janus face” in tumor biology because (a) it is associated with restrained proliferation, differentiation, necrosis or apoptosis, and (b) it can also lead to the development of an aggressive phenotype. Independent of standard prognostic factors, such as tumor stage and nodal status, hypoxia has been suggested as an adverse prognostic factor for patient outcome. Studies of tumor hypoxia involving the direct assessment of the oxygenation status have suggested worse disease-free survival for patients with hypoxic cervical cancers or soft tissue sarcomas. In head & neck cancers the studies suggest that hypoxia is prognostic for survival and local control. Technical limitations of the direct O2 sensing technique have prompted the use of surrogate markers for tumor hypoxia, such as hypoxia-related endogenous proteins (e.g., HIF-1α, GLUT-1, CA IX) or exogenous bioreductive drugs. In many—albeit not in all—studies endogenous markers showed prognostic significance for patient outcome. The prognostic relevance of exogenous markers, however, appears to be limited. Noninvasive assessment of hypoxia using imaging techniques can be achieved with PET or SPECT detection of radiolabeled tracers or with MRI techniques (e.g., BOLD). Clinical experience with these methods regarding patient prognosis is so far only limited. In the clinical studies performed up until now, the lack of standardized treatment protocols, inconsistencies of the endpoints characterizing the oxygenation status and methodological differences (e.g., different immunohistochemical staining procedures) may compromise the power of the prognostic parameter used.

Association between Tumor Hypoxia and Malignant Progression in Advanced Cancer of the Uterine Cervix

Abstract: Experimental tumors contain a significant fraction of microregions that are chronically or transiently hypoxic. Experimental evidence showing that hypoxia (and subsequent reoxyenation) may have a profound impact on malignant progression and on responsiveness to therapy is growing. The clinical relevance of tumor oxygenation in human solid malignancies is under investigation. We have developed and validated a clinically applicable method for measurement of tumor oxygenation in locally advanced cancer of the uterine cervix using a computerized polarographic electrode system. Applying this procedure in patients with cervical cancers ≥3 cm in diameter, who gave informed consent, we have been studying the clinical relevance of tumor oxygenation prospectively since 1989. As of June 1995, 103 patients with advanced cancers of the uterine cervix [Federation Internationale des Gynaecologistes et Obstetristes (FIGO) stages Ib, bulky ( n = 13), IIa and IIb ( n = 51), IIIa and IIIb ( n = 34), and IVa and IVb ( n = 5)] had entered the study. Fifty % of the patients had carcinomas with median pO 2 readings hypoxic tumors. Tumor oxygenation was found to be independent of various patient demographics and also of pretreatment tumor characteristics, such as clinical tumor stage and size, histological type, and differentiation. However, histopathological examination of the surgical specimens following radical tumor resection in 47 patients showed that low-pO 2 tumors exhibited larger tumor extensions and more frequent (occult) parametrial spread, as well as lymph-vascular space involvement, compared to well-oxygenated tumors of similar clinical stage and size. Forty-two patients completing primary radiation therapy and 47 patients who underwent radical surgery were analyzed for treatment outcome after a median observation period of 28 months (range, 3–76 months). Patients with hypoxic tumors had significantly worse disease-free and overall survival probabilities compared to patients with nonhypoxic tumors. Cox regession analysis identified tumor oxygenation and FIGO stage as the most important independent prognostic factors. The poorer outcome of the patients with hypoxic tumors was mainly due to locoregional failures with and without distant metastases, irrespective of whether surgery or radiation was applied as primary treatment. Tumor oxygenation as measured with a standardized polarographic method proved to be a powerful new pretherapeutic prognostic parameter providing important information on malignant progression in terms of extracervical tumor spread and radioresistance in advanced cervical cancers.

Tumor oxygenation predicts for the likelihood of distant metastases in human soft tissue sarcoma.

Abstract: This study was performed to explore the relationship between tumor oxygenation and treatment outcome in human soft tissue sarcoma. Twenty-two patients with nonmestastatic, high-grade, soft tissue sarcomas underwent preoperative irradiation and hyperthermia and pretreatment measurement of tumor oxygenation. The 18-month actuarial disease-free survival was 70% for patients with tumor median oxygen pressure (pO2) values of >10 mm Hg but only 35% for those with median pO2 values of <10 mm Hg (P=0.01). There were eight treatment failures; the first site of recurrence was lung in all patients. Median pO2 was 7.5 mm Hg for metastasizing tumors versus 20 mm Hg for nonmetastasizing tumors (P=0.03). Potential mechanisms and implications for clinical trial design are discussed.