Darragh Halpenny MBBCh, MRCPI, Presenter: Nothing to Disclose

Carole A. Ridge MD, Abstract Co-Author: Nothing to Disclose

Sara Anne Hayes MD,MBBCh, Abstract Co-Author: Nothing to Disclose

Junting Zheng, Abstract Co-Author: Nothing to Disclose

Chaya Moskowitz, Abstract Co-Author: Nothing to Disclose

Andreas Rimner MD, Abstract Co-Author: Research Consultant, General Electric Company

Michelle Segall Ginsberg MD, Abstract Co-Author: Nothing to Disclose

Stereotactic body radiation therapy (SBRT) is a therapeutic option for patients with stage I non-small cell lung cancer who may not be surgical candidates. SBRT delivers highly targeted, high dose radiation. The post-treatment radiological appearance is different compared with conventional radiotherapy (CRT). The objective of this study is to identify computed tomography (CT) features predictive of local recurrence after SBRT

The institutional review board approved this study. 218 consecutive patients underwent SBRT (4000-6000 cGy, 3-5 fractions over 1-2 weeks) for local control of lung cancer from Jan 1, 2006-Mar 1, 2011. CT images were retrospectively, independently reviewed by 2 radiologists. CT studies prior to SBRT and at 6, 12 + 24 months after SBRT were evaluated. Signs of local recurrence recorded were: opacity with a new bulging margin, opacification of air bronchograms, new or enlarging pleural effusion, new or enlarging mass and increase in lung density at the treatment site. End points assessed were local recurrence (biopsy proven or on PET/CT) and death. Landmark analyses at 6 months, 12 months and 24 months were performed to examine the association between CT features and local recurrence free survival (LRFS).

89 of the 218 treated patients were included as they had radiologic follow-up of at least 24 months. 10 (11.2%) patients had local recurrence. 31 (34.8%) patients died within the period of follow up. None of the 5 morphological features usually associated with CRT were significantly associated with LRFS after SBRT (p>0.05). Nodal recurrence at 12 and 24 months was significantly associated with LRFS. Nodal recurrence at 12 months conferred a 50% (95%CI: 19%-100%) chance of being event free at 36 months compared to those with no nodal recurrence (66%, 95%CI: 54%-79%, p = 0.023 both readers, kappa=1.00). Patients had a higher chance of local recurrence or death at 36 months when they had nodal recurrence at 24 months (47% vs 29%, p=0.026, and 64% vs 26%, p<.001 for reader 1 & reader 2, kappa=0.86, 95% CI: 0.68 – 1.00).

No local recurrence features identified on CT associated with CRT were associated with SBRT. Nodal recurrence was significantly associated with local recurrence free survival.

Radiological patterns of local recurrence associated with CRT may not be predictive of local recurrence in patients receiving SBRT for early stage lung cancer

Halpenny, D, Ridge, C, Hayes, S, Zheng, J, Moskowitz, C, Rimner, A, Ginsberg, M, Are There Computed Tomography Features Predictive of Local Recurrence in Patients with Early Stage Non-small Cell Lung Cancer Treated with Stereotactic Body Radiation Therapy? .  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13017983.html