Higher Post-Treatment FDG-PET Standardized Uptake Value Associated With Poorer Survival in Locally Advanced NSCLC
In a trial (ACRIN 6668/RTOG 0235 trial) reported in Journal of Clinical Oncology, Mitchell Machtay, MD, of Case Western Reserve University, and colleagues assessed the relationship between standardized uptake value for 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) and survival in patients with stage III non–small cell lung cancer (NSCLC). Higher post-treatment standardized uptake value was associated with poorer survival, although clear cutoff values for clinical use remain to be identified.
Study Details
In this prospective National Cancer Institute–funded American College of Radiology Imaging Network (ACRIN)/Radiation Therapy Oncology Group (RTOG) cooperative group trial, pretreatment (n = 226) and post-treatment (n = 173) peak and maximum standardized uptake values were measured in patients with stage III NSCLC receiving conventional concurrent platinum-based chemoradiotherapy without surgery. Postradiotherapy consolidation chemotherapy was allowed. Post-treatment FDG-PET was performed at approximately 14 weeks after radiotherapy. Post-treatment standardized uptake value was the primary endpoint.
The most common chemotherapy regimen was carboplatin/paclitaxel (42% of patients), 45% of patients received post-radiotherapy adjuvant chemotherapy, and the most common radiotherapy dose was 60 to 70 Gy (72%).
Post-Treatment Standardized Uptakes Value Associated With Survival
The 2-year survival rate for the entire population was 42.5%. Pretreatment peak and maximum standardized uptake values (mean 10.3 and 13.1, respectively) were not associated with survival either as continuous or categorical variables on univariate or multivariate analyses.
Mean post-treatment peak and maximum standardized uptake values were 3.2 and 4.0, respectively. When analyzed as a prespecified binary value of ≤ 3.5 vs > 3.5, there was no association of peak standardized uptake value with survival. When analyzed as a continuous variable, peak standardized uptake value was significantly associated with survival (hazard ratio [HR] = 1.086, P = .011). The hazard ratio in the multivariate model was 1.087 (P = .020), indicating that an increase of 1.0 point in post-treatment peak standardized uptake value was associated with a 9% increase in the risk of death. In subgroup analyses, significant associations with survival were found using peak standardized uptake value cutoffs of 5.0 (P = .041) and 7.0 (P = .001). All results were similar when maximum standardized uptake value was used in univariate and multivariate models in place of peak standardized uptake value.
The investigators concluded:“Higher post-treatment tumor [peak or maximum standardized uptake value] is associated with worse survival in stage III NSCLC, although a clear cutoff value for routine clinical use as a prognostic factor is uncertain at this time…. Further investigation of the role of post-treatment FDG-PET in therapeutic decision making in this clinical setting is warranted.”
The study was supported by ACRIN and RTOG through National Cancer Institute funding.
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