Thistlethwaite A J, Leeper D B, Moylan D J, Nerlinger R E
Int J Radiat Oncol Biol Phys. 1985 Sep;11(9):1647-52. doi: 10.1016/0360-3016(85)90217-2.
The effectiveness of hyperthermia in tumor therapy may depend on a lower extracellular pH of tumor compared to that of normal tissue. A technique for measuring extracellular pH in human tumors has been devised to test the usefulness of this parameter as prognostic indicator of tumor hyperthermia response. In a preliminary study 50 of 53 pH readings from 14 human tumors (both heated and unheated) were below normal physiological pH. Tumor pH values ranged between 5.55-7.69 (average for unheated tumors 6.81 +/- 0.09, SEM, only one determination was above 7.40). Although there was considerable heterogeneity of pH within tumors, the accuracy and drift of the 21 gauge needle electrode were not a problem. Fifteen minutes were required for pH stabilization after insertion of an 18 gauge open-ended catheter, and less than 5 min for equilibration after electrode insertion into the catheter. A saline wheal was used for anesthesia to preclude modification of pH by anesthetics. Central portions of tumors were no more acidic than peripheral regions, but large tumors tended to be more acidic than small tumors. The pH of several tumors of various sizes and histologies was also determined immediately before subsequent treatment sessions. These measurements were made by reinsertion of catheters in approximately the same locations at each session. The trend appeared to be that pH increased with the number of treatment sessions. Measurements of pH were made in four patients immediately prior to and at the termination of a heating session (same locations since catheter remained in place during heating sessions). Three of the four tumors showed increased pH readings of 0.25-0.54 units during heating. However, none of the four tumors achieved temperatures exceeding 42 degrees C. The pH measurement technique developed provides a safe and relatively easy method for determining extracellular pH in human tumors. There appears to be a correlation of pH values with tumor size, treatment session, and possibly blood flow.
热疗在肿瘤治疗中的有效性可能取决于肿瘤细胞外pH值低于正常组织这一情况。已设计出一种测量人体肿瘤细胞外pH值的技术，以检验该参数作为肿瘤热疗反应预后指标的实用性。在一项初步研究中，来自14例人体肿瘤（包括加热和未加热的）的53次pH读数中有50次低于正常生理pH值。肿瘤pH值范围在5.55 - 7.69之间（未加热肿瘤的平均值为6.81 +/- 0.09，标准误，只有一次测定值高于7.40）。尽管肿瘤内pH值存在相当大的异质性，但21号针电极的准确性和漂移不是问题。插入18号开放式导管后，pH值稳定需要15分钟，电极插入导管后平衡时间不到5分钟。使用盐水皮丘进行麻醉，以防止麻醉剂改变pH值。肿瘤中心部分并不比周边区域更酸，但大肿瘤往往比小肿瘤更酸。在后续治疗疗程之前，还立即测定了几种不同大小和组织学类型肿瘤的pH值。这些测量是通过在每个疗程中将导管重新插入大致相同的位置进行的。趋势似乎是pH值随着治疗疗程的增加而升高。在四名患者中，在加热疗程开始前和结束时（由于加热疗程期间导管保持在位，所以位置相同）立即进行了pH值测量。四个肿瘤中有三个在加热期间pH读数升高了0.25 - 0.54个单位。然而，四个肿瘤中没有一个达到超过42摄氏度的温度。所开发的pH测量技术为测定人体肿瘤细胞外pH值提供了一种安全且相对简便的方法。pH值似乎与肿瘤大小、治疗疗程以及可能的血流存在相关性。
