Relating acute esophagitis to radiotherapy dose using FDG-PET in concurrent chemo-radiotherapy for locally advanced non-small cell lung cancer

Abstract: Purpose: To correlate radiotherapy (RT) dose to acute esophagitis (AE) by means of FDG-PET scans acquired after concurrent chemo-radiotherapy (cCRT) for locally advanced non-small-cell lung cancer (NSCLC). Materials and methods: Patients treated with 24×2.75Gy were selected on presence of a post-RT PET (PETpost) scan acquired within 3months after cCRT. The value of PETpost in relation to AE was evaluated by comparing the mean esophageal SUV of the highest 50% (〈SUV50%〉) between gr<2 and gr⩾2AE. The local dose on the esophagus wall was correlated to the SUV and modeled using a power-law fit. The Lyman–Kutcher–Burman (LKB) model was used to predict gr⩾2AE. The local dose–response relation was used in the LKB model to calculate the EUD. Resulting prediction accuracy was compared to D mean, V 35, V 55 and V 60. Results: Eighty-two patients were included (gr<2=25, gr⩾2=57). The 〈SUV50%〉 was significantly higher for gr⩾2AE (2.2 vs. 2.6, p <0.01). The LKB parameters (95% CI) were n =0.130 (0.120–0.141), m =0.25 (0.13–0.85) and TD50 =50.4Gy (37.5–55.4), which resulted in improved predictability of AE compared to other predictors. Conclusion: Esophageal uptake of FDG post-cCRT reflects AE severity. Predictability of grade ⩾2AE was improved by using the local dose–SUV response model, with narrow confidence intervals for the optimized LKB parameters. [Copyright &y& Elsevier]