Re-Examining the Role of Elective Nodal Irradiation

Abstract

Elective nodal irradiation (ENI) of regional lymphatics has been a foundational paradigm for radiation oncologists in the treatment of nonsmall-cell lung cancer (NSCLC), but its utility has recently been called into question. This review summarizes the controversies surrounding ENI and reviews the therapeutic options available to treat regional lymphatics in NSCLC. Local failure after conventional radiotherapy (RT) occurs in 40% to 80% of patients fueling the investigation of more aggressive RT regimens. As the dose is increased and accelerated the volume of normal lung tissue treated becomes a limiting factor. Thus elimination of ENI followed by further dose escalation has become a commonly pursued solution. When ENI is excluded, treatment is restricted to clinically positive disease and negative lymph node stations are left untreated. Radiographic and surgical data suggest our ability to determine the true extent of disease is imperfect and therefore the elimination of ENI likely leaves microscopic NSCLC untreated. At our institution we have concluded that the prophylactic treatment of regional lymph nodes is best reserved for patients most likely to achieve local control and are designing treatment protocols including chemotherapy to take advantage of this improvement in local control.