Elective Nodal Irradiation (ENI) Doesn't Appear to Provide a Clear Benefit for Patients With Unresectable Non–Small-Cell Lung Cancer (NSCLC)

Abstract

Elective nodal irradiation (ENI) is the irradiation of clinically uninvolved lymph node to account for microscopic tumor invasion of these lymph nodes. Dr. Belderbos et al., under the auspices of the International Atomic Energy Agency, have compiled a very thorough summary of the literature regarding ENI for non–small-cell lung cancer (NSCLC). Their major conclusion was, ‘‘The clinical value of ENI is uncertain.’’ However, it is my opinion that the evidence suggests that purposeful elective nodal irradiation is unlikely to improve patient outcomes and can increase toxicity. Thus suggesting that ENI is not beneficial. Additionally, the purposeful inclusion of ENI may hinder progress in treating NSCLC because it is likely to make the safe escalation of RT dose more challenging. This discussion will focus primarily on Stage III NSCLC because that is situation with which radiation oncologists are most often faced. The argument against the use of ENI may be summarized as follows. First, failure is uncommon in nodal regions that are neither clinically involved nor specifically targeted. Belderbos et al. published the result of a trial that is an excellent example. This study included both positron emission tomography and computed tomography scanning, which is consistent with modern state-of-the-art, noninvasive staging. This radiation therapy (RT) dose-escalation trial prospectively evaluated the incidence of isolated nodal failure with omission of the ENI (1). Only the metabolic active lymph nodes were included in the gross target volume. Positron emission tomography scans were obtained shortly before the RT in treatment position. Two (3%) of the 67 positron emission tomography–staged patients developed isolated nodal failures. These results are quite similar to other published reports (2, 3). Second, it appears that a dose greater than the conventional 60–70 Gy is required to cure a larger fraction of NSCLC patients. Le Chevalieret al. reported the results of a randomized