Abstract B32: The impact of PET-CT on staging, management, and prognostication of small cell lung cancer.
Authors: Zer Alona , Rapson Yael , Nadam Meital , Flex Dov , Allen Aaron M. , Stemmer Salomon M. , Groshar David , Bernstine Hanna 
Published: August 2014

Introduction: Although frequently used, there is no randomized data assessing the role of PET CT in the staging process of SCLC patients, or its impact on patients' management. We aimed to review retrospectively the utility of PET-CT in patients diagnosed with SCLC in a single tertiary medical center and to address these issues.

Methods: We included all patients diagnosed with SCLC between January 2007 and December 2011 at Rabin Medical Center (Petach-Tikva, Israel), either staged by PET-CT or not. Data retrieved included: age, gender, Veteran's staging (LD or ED, as determined by the institute multidisciplinary team during thoracic tumor-board meeting), ECOG performance status, staging procedures done and their results (FDG-PET scan, CT scans, MRIs, Bone Scans, BMBs), pathology immunohistochemistry characteristics (Ki67, chromogranin, synaptophysin), serum markers levels (NSE, LDH, chromogranin, CEA), treatment modality (chemotherapy versus chemoradiation), Disease Free Survival (DFS), Progression Free Survival (PFS) and Overall Survival (OS). In the group of patients who underwent PET CT during the initial evaluation, we re-assessed staging, both according to the Veteran's Administration Lung Group's 2-stage classification (LD and ED) and according to the American Joint Committee on Cancer Staging manual, 7th edition (TNM). Staging was performed by two independent radiologists: one (HB), a nuclear medicine specialist, to decide on the stage according to PET-CT findings, and the other (YR), thoracic radiologist, to decide on the stage according to chest, abdomen and pelvic contrast-enhanced CT scan findings (with bone scan results if available) and blinded to the PET results. PET scans were also evaluated for SUVmax (maximal standardized uptake value) and TLG (total lesion glycolysis).

Results: 108 patients were diagnosed and treated for SCLC in the above mentioned period. 2 patients were excluded from the analysis for lack pathology or staging procedure data and 10 patients were excluded since their PET imaging was done elsewhere, not accessible for our assessment. Finally, out of 96 patients, 54 had a PET-CT done as part of their staging procedure.

PET-staged patients had significantly less staging procedures done than non-PET-staged patients (24% underwent 3-4 staging procedures versus 62%, p=0.04). PET altered management in 19 patients (35%), with 13 patients with suspected metastatic disease, who benefited from down-staging by PET.

It appears that treatment was significantly delayed in PET-staged patients with a mean of 30 days from diagnostic procedure to treatment versus 26 days (p=0.04).

TLG was found to correlate with OS and PFS, with high TLG level predicting poorer survival (HR=3.38, CI 1.385-8.259, p=0.007).

Conclusions: Although PET-CT adds to SCLC patients' management by reducing the amount of staging procedures and possibly down staging patients who otherwise would have been treated with palliative intent, in the setup of a public tertiary medical center, waiting for the PET to be done and reported could result in treatment delay. Randomized data is necessary to properly evaluate the sensitivity, specificity and influence on management of this modality. TLG appears to be a new promising prognostic biomarker in small cell lung tumors.

Citation Format: Alona Zer, Yael Rapson, Meital Nadam, Dov Flex, Aaron M. Allen, Salomon M. Stemmer, David Groshar, Hanna Bernstine. The impact of PET-CT on staging, management, and prognostication of small cell lung cancer. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr B32.