PubMed · 10919431
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R Thomas, K J Power. 2000. Interpreting the base deficit.. https://doi.org/10.1046/j.1365-2044.2000.01557-4.x
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Cytoreductive nephrectomy prior to systemic therapy significantly increases survival in patients with metastatic renal cancer. This result is generally ascribed to the benefits of resection of the primary tumor including reduction of tumor burden, removal of a source for growth factors and metastases, and enhanced immune response. On the basis of mathematical models of tumor invasion, we propose that the observed effects of cytoreductive nephrectomy may be caused by resection of the kidney rather than the cancer. The models predict that the graded metabolic acidosis associated with mild renal failure after unilateral nephrectomy may alter the dynamics of the tumor-host interface sufficiently to reduce and even reverse the rate of invasion. A review of patient data from the surgical arm of the Southwest Oncology Group (SWOG) 8949(2) trial demonstrates significantly improved survival in patients who experienced postoperative increase in blood urea nitrogen (BUN) and creatinine compared with those who did not (17-month survival versus 4-month survival; P = 0.0007). This is generally consistent with the predictions of the mathematical models. If confirmed, these results suggest novel and broadly applicable tumor therapies.
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BACKGROUND: Glioblastoma commonly is characterized by hypoxia and acidosis and the histologic features of tissue necrosis and neovascularization. Current approaches of adjuvant radiochemotherapy for patients with glioblastoma have only a modest impact on the natural course of this disease. METHODS: The authors examined the effects of acidosis on growth and response to irradiation and chemotherapy in cultured human malignant glioma cells. RESULTS: The authors found that mild acidosis (pH 7.0) inhibited the growth of cell lines that retained wild type p53 activity but did not inhibit the growth of cell lines that were devoid of p53 function. Transfer of a dominant-negative p53 gene into p53 wild type cells failed to override the acidosis-conferred growth arrest, suggesting that loss of p53 activity per se does not mediate escape from acidosis-induced growth inhibition. Moderate acidosis (pH 6.6) inhibited the growth of all cell lines. Acidosis-mediated growth arrest was not associated with a specific type of cell cycle arrest, e.g., in G0/G1 or G2/M phase. Acidosis did not result in consistent changes in radiosensitivity; however, it enhanced the cytotoxic effects of lomustine but conferred protection from topotecan, vincristine, teniposide, and cisplatin cytotoxicity. Lomustine exhibited enhanced stability at low pH, providing a putative mechanism for the enhanced cytotoxic effects of lomustine in acidotic conditions. Decreased sensitivity to the other drugs did not result from altered multidrug resistance drug transport activity. CONCLUSIONS: Taken together, the current results suggest that tissue acidosis may be an important determinant of glioma cell responses to adjuvant radiochemotherapy. The superior activity of nitrosoureas, such as lomustine, compared with other agents in patients with glioblastoma may result in part from prolonged drug stability in an acidotic microenvironment.