Nitin Ohri MD, Presenter: Nothing to Disclose

Ying Xiao PhD, Abstract Co-Author: Nothing to Disclose

Maria Werner-Wasik MD, Abstract Co-Author: Nothing to Disclose

Small-cell lung cancer (SCLC) is thought to progress rapidly. Here we utilize pre-treatment CT scans from limited-stage SCLC patients to quantify disease growth rates and assess their significance.

We reviewed the records of limited-stage SCLC patients treated at our institution. Patients with more than one pre-treatment CT scan (including PET-CT and radiotherapy planning imaging) were identified. A single observer contoured primary tumors and enlarged lymph nodes on each pre-treatment CT scan using lung and/or mediastinal window levels, as appropriate. For each scan, the gross tumor volume (GTV) was defined as the sum of all contoured volumes. GTV doubling time (VDT) was calculated for each patient using an exponential growth model. Tumor growth rate, tumor volume, and clinical factors such as age and performance status were tested as predictors of progression-free survival (PFS) using Cox proportional hazards modeling.

12 patients were suitable for this analysis. All were treated with chemotherapy and concurrent, hyperfractionated thoracic radiotherapy. The median time interval between the first and last pre-treatment CT scan was 35 days (range: 6-111). Median GTV was 48.1 cm3 (range: 6.1-214.6) on the first scan and 57.6 cm3 (range: 12.4-260.2) on the second scan. GTV increased in all cases, by a median of 37.4% (range: 5.0-135.8). Median VDT was 89 days (range: 13-150). With a median follow-up of 20.3 months for living patients, 9 patients have developed local and/or distant failure. Median PFS for all patients was 6.7 months. VDT of greater than 90 days was associated with decreased PFS (HR = 3.21, 95% CI: [0.60-17.08]), but this did not reach statistical significance (p = 0.171).

SCLC progresses rapidly before the initiation of therapy. Rapid growth rate may be associated with improved response to chemoradiotherapy.

Small cell lung cancer progresses rapidly before initiation of therapy, and tumor growth rate may have prognostic implications.

Ohri, N, Xiao, Y, Werner-Wasik, M, Volumetric Assessment of Limited Stage Small Cell Lung Cancer Growth before Treatment.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11004518.html