Exploring dose-intensity: carefully comparing high-dose with low-dose external-beam radiotherapy for prostate cancer. Clinical Oncology

摘要

It is nearly axiomatic that higher doses of radiotherapy will result in fewer surviving cancer clonogens within the radiotherapy target, and this strongly held hypothesis has guided radiotherapy investigations over the last two decades.1 Radiation oncologists have been mindful of the two-edged nature of dose intensification and have carefully monitored patients for late toxicity in the context of clinical trials that have tested the dose-intensification hypothesis. Unfortunately, the results of more intense radiotherapy have been mixed, with many situations showing no long-term benefit with higher doses of radiotherapy. The absence of benefit may be explained by subclinical metastatic disease and a lack of highly effective treatment for this component of cancer, but even in conditions with a highly localized neoplasm (primary glial tumors), substantial dose escalation has sometimes been ineffective and perhaps resulted in increased toxicity.2,3 Thus, despite the self-evident nature of our axiom and years of investigation, careful clinical studies are still warranted before higher doses can be routinely used.