Radiation Medicine and Protection (Jun 2021)
Dose escalation guided by 18F-FDG PET/CT for esophageal cancer
Abstract
Objective: To assess the feasibility of dose escalation guided by 18F-deoxyglucose positron emission tomography/computer tomography (18F-FDG PET/CT) for esophageal cancer (EC). Methods and materials: Ten random patients treated with definitive chemoradiotherapy and pre-therapeutic 18F-FDG PET/CT were included in this study. Retrospectively, a threshold of 50% of SUVmax was used to define the high FDG uptake region of the GTV (GTVPET). Three intensity-modulated radiation therapy (IMRT) plans were generated, delivering three dose levels to three different planning target volumes (PTVs). 50.4 Gy delivered to PTV50.4 was defined on computed tomography (CT) as Plan50.4, 63 Gy was delivered to PTV63 was defined as GTV plus a uniform margin of 0.5 cm as Plan63, and 70 Gy delivered to PTV70 was defined as GTVPET plus a 0.5 cm margin as Plan70. A dosimetric comparison was performed based on normal tissue complication probability (NTCP) for the lung and heart. Results: Clinically acceptable dose escalation failed for 2 of 10 patients in Plan63 due to heart dose constraints. One patient failed heart dose constraint for Plan70. Two patients failed spinal cord constraint for Plan63. Three patients failed lung dose constraints for both Plan63 and Plan70, two of which were even not suitable for Plan50.4 for the same reason.NTCP modeling for lung showed increased risk for Plan63 and Plan70 compared to Plan50.4. The difference between Plan63 and Plan70 was insignificant. NTCP modeling for heart showed an increased risk from 6.38% of Plan50.4 to 8.88% of Plan70 (P = 0.009) or 9.79% of Plan63 (P = 0.007). The risk of heart mortality was significantly higher for Plan63 than Plan70 (P = 0.047). Conclusions: Selective boosting of sub-volumes based on 18F-FDG PET/CT is feasible way with a modest increase in the risk of cardiac and lung toxicities.
