Prognostic value of metabolic metrics extracted from baseline positron emission tomography images in non-small cell lung cancer

Abstract

Background. Maximum, mean and peak SUV of primary tumor at baseline FDG-PET scans, have often been found predictive for overall survival in non-small cell lung cancer (NSCLC) patients. In this study we further investigated the prognostic power of advanced metabolic metrics derived from intensity volume histograms (IVH) extracted from PET imaging. Methods. A cohort of 220 NSCLC patients (mean age, 66.6 years; 149 men, 71 women), stages I–IIIB, treated with radiotherapy with curative intent were included (NCT00522639). Each patient underwent standardized pre-treatment CT-PET imaging. Primary GTV was delineated by an experienced radiation oncologist on CT-PET images. Common PET descriptors such as maximum, mean and peak SUV, and metabolic tumor volume (MTV) were quantified. Advanced descriptors of metabolic activity were quantified by IVH. These comprised five groups of features: absolute and relative volume above relative intensity threshold (AVRI and RVRI), absolute and relative volume above absolute intensity threshold (AVAI and RVAI), and absolute intensity above relative volume threshold (AIRV). MTV was derived from the IVH curves for volumes with SUV above 2.5, 3 and 4, and of 40% and 50% maximum SUV. Univariable analysis using Cox Proportional Hazard Regression was performed for overall survival assessment. Results. Relative volume above higher SUV (80%) was an independent predictor of OS (p = 0.05). None of the possible surrogates for MTV based on volumes above SUV of 3, 40% and 50% of maximum SUV showed significant associations with OS [p (AVAI₃) = 0.10, p (AVAI₄) = 0.22, p (AVRI_40%) = 0.15, p (AVRI_50%) = 0.17]. Maximum and peak SUV (r = 0.99) revealed no prognostic value for OS [p (maximum SUV) = 0.20, p (peak SUV) = 0.22]. Conclusions. New methods using more advanced imaging features extracted from PET were analyzed. Best prognostic value for OS of NSCLC patients was found for relative portions of the tumor above higher uptakes (80% SUV).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

We acknowledge financial support from the QuIC–ConCePT project, which is partly funded by EFPI A companies and the Innovative Medicine Initiative Joint Undertaking (IMI JU) under Grant Agreement No. 115151. We also acknowledge financial support from the National Institute of Health (NIH–USA U01 CA 143062–01, Radiomics of NSCLC), the CTMM framework (AIRFORCE project, grant 030-103), EU 6th and 7th framework program (EUROXY, METOXIA, EURECA, ARTFORCE), euroCAT (IVA Interreg – www.eurocat.info), Kankeronderzoekfonds Limburg from the Health Foundation Limburg and the Dutch Cancer Society (KWF UM 2011–5020, KWF UM 2009–4454).