Höckel M, Vaupel P
Department of Obstetrics and Gynecology, University of Leipzig, Germany.
J Natl Cancer Inst. 2001 Feb 21;93(4):266-76. doi: 10.1093/jnci/93.4.266.
Tissue hypoxia results from an inadequate supply of oxygen (O(2)) that compromises biologic functions. Evidence from experimental and clinical studies increasingly points to a fundamental role for hypoxia in solid tumors. Hypoxia in tumors is primarily a pathophysiologic consequence of structurally and functionally disturbed microcirculation and the deterioration of diffusion conditions. Tumor hypoxia appears to be strongly associated with tumor propagation, malignant progression, and resistance to therapy, and it has thus become a central issue in tumor physiology and cancer treatment. Biochemists and clinicians (as well as physiologists) define hypoxia differently; biochemists define it as O(2)-limited electron transport, and physiologists and clinicians define it as a state of reduced O(2) availability or decreased O(2) partial pressure that restricts or even abolishes functions of organs, tissues, or cells. Because malignant tumors no longer execute functions necessary for homeostasis (such as the production of adequate amounts of adenosine triphosphate), the physiology-based definitions of the term "hypoxia" are not necessarily valid for malignant tumors. Instead, alternative definitions based on clinical, biologic, and molecular effects that are observed at O(2) partial pressures below a critical level have to be applied.
组织缺氧是由于氧气（O₂）供应不足而损害生物功能所致。实验和临床研究的证据越来越多地表明缺氧在实体瘤中起重要作用。肿瘤中的缺氧主要是结构和功能紊乱的微循环以及扩散条件恶化的病理生理后果。肿瘤缺氧似乎与肿瘤增殖、恶性进展和治疗抵抗密切相关，因此已成为肿瘤生理学和癌症治疗的核心问题。生物化学家、临床医生（以及生理学家）对缺氧的定义不同；生物化学家将其定义为O₂限制的电子传递，而生理学家和临床医生将其定义为O₂可用性降低或O₂分压降低的状态，这种状态会限制甚至消除器官、组织或细胞的功能。由于恶性肿瘤不再执行维持体内平衡所需的功能（如产生足够量的三磷酸腺苷），“缺氧”一词基于生理学的定义对恶性肿瘤不一定有效。相反，必须应用基于在低于临界水平的O₂分压下观察到的临床、生物学和分子效应的替代定义。
