10.6084/m9.figshare.5669662.v1 M. Kandi M. Kandi L. Hoffmann L. Hoffmann D. Sloth Moeller D. Sloth Moeller H. H. Schmidt H. H. Schmidt M. M. Knap M. M. Knap A. A. Khalil A. A. Khalil Local failure after radical radiotherapy of non-small cell lung cancer in relation to the planning FDG-PET/CT Taylor & Francis Group 2017 non-small cell lung cancer p-CT lymph node mapping rec lymph node irradiation station 2 R pt FDG-PET SUVp 50 station 4 R volume T-rec GTV NSCLC CT p-PET Additional confirmatory studies LN 2017-12-05 12:43:11 Journal contribution https://tandf.figshare.com/articles/journal_contribution/Local_failure_after_radical_radiotherapy_of_non-small_cell_lung_cancer_in_relation_to_the_planning_FDG-PET_CT/5669662 <p><b>Objectives:</b> Local recurrence (rec) in lung cancer is associated with poor survival. This study examined whether the pattern of failure is associated with the most PET avid volume in the planning-FDG-PET/CT scan (p-PET/CT).</p> <p><b>Methods:</b> 162 consecutive inoperable NSCLC patients (pts) receiving radiotherapy between January 2012 and April 2014 were reviewed. Radiotherapy was delivered in 2 Gy/fraction (5f/week) to a total dose of 60–66 Gy. Pts were followed with CT scans every third month. Patients with local rec as first event were analyzed. For the primary tumor (T) the overlap-fraction (OF) between 50% of SUV<sub>peak</sub> on p-PET/CT and the volume of T-rec was calculated: OF = (SUV<sub>p50</sub>∩T-rec)/min(SUV<sub>p50</sub>, T-rec). Similarly for the GTV on the p-CT: OF = (GTV∩T-rec)/min(GTV, T-rec). OF was based on a rigid registration between p-PET/CT and rec-CT with PET guided delineation of T- rec. For lymph nodes (LN), the correlation between the location of treated-LN and the location of recurrence-LN was evaluated.</p> <p><b>Results:</b> 67 patients developed local rec. 51 pts had rec in T-site, 45 pts in LN-site. Due to anatomical changes, reliable registration between p-CT and rec-CT was only obtained in 26 pts with T-rec. The median OF<sub>SUVp50</sub> was 52, 8% [range 26; 100%] and the median OF<sub>GTV</sub> was 80.5% [19.7; 100%]. Eleven pts had higher OF<sub>SUVp50</sub> than OF<sub>GTV</sub>. LN-rec predominantly occurred in the station 2R (32%), 4R (46%), 7 (46%) and right hilum (36%). Pts with malignant LNs in station 4R or 7 on p-CT had a high risk of rec in these stations; 4R (55%) and 7 (83%).</p> <p><b>Conclusions:</b> This study indicates that the most PET active volume on p-PET-CT is a driver for rec at T-site. LN-recurrences predominantly appear in station 2R, 4R, 7 and right hilum. Additional confirmatory studies regarding lymph node mapping and selective lymph node irradiation is needed.</p>