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Title: Assessment of the Radiation-Equivalent of Chemotherapy Contributions in 1-Phase Radio-chemotherapy Treatment of Muscle-Invasive Bladder Cancer

Purpose: To estimate the radiation equivalent of the chemotherapy contribution to observed complete response rates in published results of 1-phase radio-chemotherapy of muscle-invasive bladder cancer. Methods and Materials: A standard logistic dose–response curve was fitted to data from radiation therapy-alone trials and then used as the platform from which to quantify the chemotherapy contribution in 1-phase radio-chemotherapy trials. Two possible mechanisms of chemotherapy effect were assumed (1) a fixed radiation-independent contribution to local control; or (2) a fixed degree of chemotherapy-induced radiosensitization. A combination of both mechanisms was also considered. Results: The respective best-fit values of the independent chemotherapy-induced complete response (CCR) and radiosensitization (s) coefficients were 0.40 (95% confidence interval −0.07 to 0.87) and 1.30 (95% confidence interval 0.86-1.70). Independent chemotherapy effect was slightly favored by the analysis, and the derived CCR value was consistent with reports of pathologic complete response rates seen in neoadjuvant chemotherapy-alone treatments of muscle-invasive bladder cancer. The radiation equivalent of the CCR was 36.3 Gy. Conclusion: Although the data points in the analyzed radio-chemotherapy studies are widely dispersed (largely on account of the diverse range of chemotherapy schedules used), it is nonetheless possible to fit plausible-looking response curves. The methodology used here is basedmore » on a standard technique for analyzing dose-response in radiation therapy-alone studies and is capable of application to other mixed-modality treatment combinations involving radiation therapy.« less
Authors:
 [1] ;  [2]
  1. Department of Oncology, Queens Hospital, London (United Kingdom)
  2. Department of Surgery and Cancer, Faculty of Medicine, Imperial College, London (United Kingdom)
Publication Date:
OSTI Identifier:
22416504
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 88; Journal Issue: 4; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BLADDER; CHEMOTHERAPY; CLINICAL TRIALS; COMBINED THERAPY; MUSCLES; NEOPLASMS; RADIOTHERAPY