Orlando, Fla., February 8, 2013 – SUVmax (Maximum Standardized Uptake Value) may be a significant and clinically independent marker to indicate progression-free survival in stage I non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiation therapy (SBRT), according to research being presented at the 2013 Cancer Imaging and Radiation Therapy Symposium. This Symposium is sponsored by the American Society for Radiation Oncology (ASTRO) and the Radiological Society of North American (RSNA).
SUVmax is measured via PET/CT scan after patients have been injected with radioactive sugar (glucose). Quantifying the SUV of suspicious lesions can aid the identification of early stage tumors because cells that take in greater than normal amounts of radioactive glucose have a higher likelihood of being tumor cells. The highest concentration of radioactive glucose represents SUVmax. Previous studies have been able to correlate SUVmax to the growth rate of tumors, which indicates that tumors with higher SUVmax will more likely be more rapidly growing and will therefore be tumors that are more difficult to treat, may recur or may metastasize more frequently.
This study included 95 medically inoperable NSCLC patients from October 2005 through May 2011, with a median age of 77 years. All patients had peripheral tumors, and no patient had been previously treated for lung cancer. Prior to SBRT treatment, all patients had an PET/CT scan with documented pretreatment SUVmax assessment. SBRT fractionation was 60 Gy in three (3) fractions with a median treatment time of six days (range of three to 21 days). With a median follow-up of 15 months, median overall survival was 25.3 months and progression-free survival was 40.3 months. Tumor control, overall and progression-free survival were derived utilizing the Kaplan-Meier method, and Cox proportional hazards regression was performed to determine whether SUVmax, age, Karnofsky Performance Status, gender, tumor size/T-stage or smoking history influenced outcomes.
"If SUVmax is assessed prior to radiation therapy, specific strategies could be developed to tailor treatments for patients, which would, in turn, provide them with the best chance at a longer and disease-free survival," said Zachary Horne, a 2013 MD candidate at the George Washington University School of Medicine in Washington, D.C., the lead study author and a researcher in the radiation oncology department at the University of Pittsburgh Cancer Institute. "Accurate anatomical and functional imaging and assessment, such as SUVmax, can help us achieve improved outcomes for patients."
The abstract, "Pretreatment SUVmax as a Marker for Progression-Free Survival in Stage I NSCLC Treated with SBRT," will be presented in detail during a scientific session at 8:00 a.m. Eastern time on Saturday, February 9, 2013. To speak with Zachary Horne, call Michelle Kirkwood on February 8-9, 2013, in the Press Office at the Hilton Orlando Lake Buena Vista in the Walt Disney World Resort at 407-560-2314 or email michellek@astro.org.
2013 Cancer Imaging and Radiation Therapy Symposium
Abstracts of Interest News Briefing, Saturday, February 9, 2013, 7:00 a.m. – 7:45 a.m. ET
Oral Presentation: Saturday, February 9, 8:00 a.m. Eastern time
8 Pretreatment SUVmax as a Marker for Progression-Free Survival in Stage 1 NSCLC Treated with SBRT
Author Block: Z. D. Horne, D. A. Clump, S. Shah, J. A. Vargo, S. A. Burton, N. A. Christie, M. J. Schuchert, R. J. Landreneau, J. D. Luketich, D. E. Heron, University of Pittsburgh Medical Center, Pittsburgh, PA
Abstract Body: Purpose: This study aims to assess pretreatment SUVmax as a prognosticator for primary stage 1 NSCLC treated with stereotactic body radiation therapy.
Materials and Methods: This study includes 95 medically inoperable patients identified between October 2005 and May 2011 (median age 77 years) with primary, biopsy-confirmed peripheral stage 1A/1B NSCLC. No tumor was located within 2cm of the proximal bronchial tree and no patient had been previously treated for lung cancer. All patients had pre-SBRT FDG-PET/CT scans with documented pretreatment SUVmax . Treatment fractionation consisted of 60Gy in 3 fractions with a median treatment time of six days (range 3-21 days). Local, regional, and distant failures specified from the last day of treatment were evaluated independently according to the terms of RTOG 1021. Tumor control, overall- and progression-free survivals were estimated by the Kaplan-Meier method. Cox proportional hazards regression was performed to determine whether SUVmax, age, KPS, gender, tumor size/T stage, or smoking history influenced outcomes. SUVmax was evaluated as both a continuous and as a dichotomous variable using a cutoff of <5 and ≥5.
Results: With a median follow-up of 15 months, median OS and PFS were 25.3 and 40.3 months, respectively. In the univariate analysis, pretreatment SUVmax with a cutoff value of 5 predicted for OS and PFS (p=0.024, each) but did not achieve significance for LC (p=0.256). On Cox univariate regression analysis, SUV as a dichotomous variable predicted for both OS and PFS (p=0.027 and p=0.030, respectively). Defined as a continuous variable, SUVmax continued to predict for OS and PFS (p=0.003, each), but also predicted LC (p=0.045) and trended toward significance for DC (p=0.064). Tumor stage, histology, KPS, and age were significant for OS on univariate analysis and were included in multivariate analyses. On ANOVA test, tumor T-stage and histology were both significantly correlated to SUVmax (p=0.013 and p<0.001, respectively). Tumor stage remained a significant predictor of OS on multivariate analysis (p=0.05), though SUVmax did not predict for OS as a dichotomous or continuous variable (p=0.209 and p=0.223, respectively). It did, however, predict for PFS as a continuous variable (p=0.009) and neared significance as a dichotomous variable (p=0.053). SUVmax also trended toward significance for local control as a continuous variable (p=0.076).
Conclusions: SUVmax appears to be a statistically and clinically significant independent prognostic marker for progression-free survival in patients with Stage 1 NSCLC treated with SBRT. Prospective studies to more accurately define the role of tumor FDG uptake in the prognosis of NSCLC are warranted.
Author Disclosure Block: Z.D. Horne: None. D.A. Clump: None. S. Shah: None. J.A. Vargo: None. S.A. Burton: None. N.A. Christie: None. M.J. Schuchert: None. R.J. Landreneau: None. J.D. Luketich: None. D.E. Heron: None.