Objective: It is known that the partial volume effect and respiratory motion blur affect quantitative parameters such as the maximum standardized uptake value (SUVmax) in FDG-PET, especially in small lesions. The purpose of this study was to assess the prognostic value of corrected SUVmax, which was corrected SUVmax for the partial volume effect and respiratory motion blur, in patients with stage I non-small cell lung cancer (NSCLC) after treatment with stereotactic body radiotherapy (SBRT). Methods: Fifty-one patients who were treated with SBRT between 2005 and 2011 in our institute were enrolled. The median tumor diameter was 2.2 cm (range 0.9–3.9 cm). The prescribed dose was typically 48 Gy in 4 fractions, 60 Gy in 8 fractions or 60 Gy in 15 fractions to the isocenter of irradiation fields. Each raw SUVmax was corrected using the recently proposed formula, and the correlations of raw SUVmax and corrected SUVmax with local control rate (LCR) were analyzed retrospectively. Results: Median raw SUVmax before SBRT was 6.4 (range 0.6–22.8). Median corrected SUVmax was 8.0 (range 0.8–22.8), which was significantly increased (p < 0.01). The median follow-up period for survivors was 45.3 months (range 18.5–82.0 months). The 3-year LCR and overall survival rates were 81.8 and 65.2 %, respectively. In univariate analysis, raw SUVmax [per 1 increase; p = 0.02, hazard ratio (HR) 1.20, 95 % confidence interval (CI) 1.03–1.42] was significantly correlated with LCR, but corrected SUVmax did not show a significant correlation with LCR (per 1 increase; p = 0.15, HR 1.07, 95 % CI 0.96–1.19). Other factors significantly correlated with LCR were diagnosis (pathological diagnosis vs. clinical diagnosis; p = 0.04, HR 6.17, 95 % CI 1.08–116) and tumor diameter (per 1 mm increase; p < 0.01, HR 1.33, 95 % CI 1.15–1.61). Conclusions: Tumor diameter was the most significant predictor of LCR after SBRT. Correction for the partial volume effect and respiratory motion blur may weaken the prognostic value of SUVmax.
- Corrected SUVmax
- Lung cancer
- Stereotactic body radiotherapy
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging