PET in lung cancer RT Incidence of isolated nodal failure in non-small cell lung cancer patients included in a prospective study of the value of PET–CT Milena Kolodziejczyk a , Krzysztof Bujko a , Wojciech Michalski b , Lucyna Kepka a,⇑ a Department of Radiation Oncology; and b Laboratory of Bioinformatics and Biostatistics, M. Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland article info Article history: Received 14 November 2011 Received in revised form 13 March 2012 Accepted 3 April 2012 Available online 29 May 2012 Keywords: Non-small cell lung cancer Radiotherapy PET–CT Elective nodal irradiation Isolated nodal failure abstract Purpose: Elective nodal irradiation (ENI) is not recommended in PET–CT-based radiotherapy for NSCLC despite a low level of evidence to support such guidelines. The aim of this investigation is to find out whether omitting ENI is safe. Materials and methods: Sixty-seven patients treated within a frame of a previously published prospective trial of the value of PET–CT were included in the analysis. Seventeen (25%) patients received ENI due to higher initial nodal involvement and in the remaining 50 patients (75%) with N0-N1 or single N2 disease ENI was omitted. Isolated nodal failure (INF) was recorded if relapse occurred in the initially uninvolved regional lymph node without previous or simultaneous local recurrence regardless of the status of distant metastases. Results: With a median follow-up of 32 months, the estimated 3-year overall survival was 42%, local pro- gression-free interval was 55%, and distant metastases-free interval was 62%. Three patients developed INF; all had ENI omitted from treatment, giving a final result of three INFs in 50 (6%) patients treated without ENI. In this group of patients, the 3-year cause-specific cumulative incidence of INF was 6.4% (95% confidence interval: 0–17%). Conclusions: The omission of ENI appears to be not as safe as suggested by current recommendations. Ó 2012 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 104 (2012) 58–61 Positron emission tomography combined with computed tomography (PET–CT) use improves the staging of non-small cell lung cancer (NSCLC) by improving both mediastinal staging and detection of distant extracranial metastases. In our recent prospec- tive study on the value of PET–CT in radiation therapy for NSCLC, 25 of 100 candidates for radical radiotherapy were not given cura- tive treatment after the PET–CT findings [1]. Data indicate that PET–CT-based radiotherapy leads to improved outcome mostly due to this stage migration [2,3]. The value of PET–CT in radiotherapy for NSCLC with regard to the determination of target volumes is recognized [4–6]. The PET–CT in the treatment of these patients is regarded as a guaran- tee of safety for the omission of elective nodal irradiation (ENI). For this reason, the use of involved-field radiation therapy (IFRT), de- fined as omission of ENI is widespread after PET–CT use. In the last European Organization for Research and Treatment of Cancer (EORTC) recommendations, the omission of ENI is grade 1B guid- ance, which means that IFRT should be applied to most patients in most circumstances without reservation [7]. However, most data on the low rate of isolated nodal failure (INF) are retrospective [8–11], and for this reason the incidence of failure may be under- reported. The low rate of INF was reported also in prospective stud- ies in which only PET–CT-positive lymph nodes were irradiated [12,13]. However, the numbers of patients in those studies were low and the follow-up times were short. We performed a prospective single-center study with the pri- mary goal of assessing the changes in radiotherapy plans in NSCLC patients after PET–CT with a focus on the risk of geographic miss caused by a lack of PET–CT information in patients with and with- out planned ENI. The study showed some but limited potential of ENI to compensate for diagnostic uncertainties [1]. The pattern of failure of patients treated with curative radiation in this study was then prospectively assessed. We report herein the survival and pattern of failure with a special focus on the risk of INF after PET–CT staging in patients treated in the frame of prospective study in which ENI was omitted only for negative or minimal nodal disease. Material and methods The details of the material and methods, and the impact of PET–CT on therapeutic decisions and radiotherapy plans, in the studied group have been reported previously [1]. In short, 100 0167-8140/$ - see front matter Ó 2012 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.radonc.2012.04.012 ⇑ Corresponding author. Address: Department of Radiation Oncology, M. Sklo- dowska-Curie Memorial Cancer Center and Institute of Oncology, UL. Roentgena 5, 02-776 Warsaw, Poland. E-mail address: lucynak@coi.pl (L. Kepka). Radiotherapy and Oncology 104 (2012) 58–61 Contents lists available at SciVerse ScienceDirect Radiotherapy and Oncology journal homepage: www.thegreenjournal.com