Intensity-Modulated Radiotherapy, Not 3 Dimensional Conformal, Is the Preferred Technique for Treating Locally Advanced Disease With High-Dose Radiotherapy: The Argument Against

摘要

Intensity-modulated radiotherapy (IMRT) allows the delivery of high-dose radiotherapy to target volumes, while sparing adjacent normal tissues. This has been mooted as a method of treating larger and otherwise untreatable lung cancers or of escalating radiotherapy doses. The possibility of achieving these aims has been confirmed in many planning studies, but there is little supporting clinical data. No randomized trial has compared conformal and IMRT, few studies have reported the late outcomes of IMRT, and there is no evidence for improved control of lung cancer with increased radiation dose. Currently IMRT should be regarded as a promising but unproven experimental therapy in locally advanced non-small cell lung cancer. Searches of PubMed were performed looking for the terms "lung cancer and radiotherapy" and "lung cancer and intensity-modulated radiotherapy." The former was carried out for the period 2007, when the author last reviewed this topic, until 2014 and the latter from the first reference to this topic to the present. The first search produced 8000 and the second 929 hits. A standard hierarchy of evidence exists for interventions in medicine, ranging from systematic reviews of randomized trials to case-control studies and mechanism-based reasoning. The best evidence so far available for IMRT in stage III lung cancer is level 3 or 4 (low level evidence), and no currently accruing phase II or phase III trials are listed on the National Cancer Institute clinical trials website, although 1 study at the MD Anderson is open but not currently recruiting patients. This evidence will be reviewed. It would not be regarded as remotely adequate for the licensing of a new pharmacologic agent, and it does not seem unreasonable that the same standards of evidence for efficacy and safety should apply to the 2 branches of nonsurgical oncology. (C) 2015 Elsevier Inc. All rights reserved.