A recent study published in BMC Medicine has shed light on the optimal radiation field size for postoperative radiotherapy (PORT) in patients with esophageal squamous cell carcinoma (ESCC). The randomized controlled trial, involving 401 patients across thirteen treatment centers, compared large-field irradiation (LFI) to small-field irradiation (SFI) in terms of disease control and survival outcomes.
The study found that while there was no statistically significant difference in overall survival (OS) between the two groups (HR=0.86, 95%CI, 0.63 to 1.16; p=0.35), LFI demonstrated a clear advantage in locoregional control. Specifically, patients in the LFI group experienced a significantly lower rate of locoregional recurrence compared to those in the SFI group (12.9% vs. 20.4%, p=0.013).
Key Findings on Disease Control
With a median follow-up of 41.8 months, the median disease-free survival (DFS) was similar in both groups: 47.9 months for LFI and 48.1 months for SFI (HR=0.87, 95%CI, 0.65 to 1.16; p=0.32). However, the locoregional recurrence-free survival (LRFS) was significantly better in the LFI group (HR=0.54, 95%CI, 0.34-0.87; p=0.01). The one-year and three-year LRFS rates were 92.3% and 83.7% for LFI, compared to 87.0% and 74.7% for SFI.
Distant metastasis-free survival (DMFS) was not significantly different between the groups (HR=1.05, 95%CI, 0.74-1.49; p=0.78), with one-year and three-year DMFS rates of 83.5% and 63.6% for LFI, and 76.3% and 66.8% for SFI.
Failure Patterns and Recurrence Sites
The analysis of failure patterns revealed that a significantly higher proportion of patients in the SFI group experienced out-of-field recurrences compared to the LFI group (14.1% vs. 4.8%, p<0.05). The lung was the most common site of distant metastasis in both groups. Notably, supraclavicular lymph node recurrences were more frequent in the SFI group (15 patients) compared to the LFI group (4 patients).
Safety and Tolerability
Treatment-related adverse events were manageable and comparable between the two groups. The most common toxicity was grade 2 radiation esophagitis, affecting 22.9% of patients in the LFI group and 16.8% in the SFI group. There were no significant differences in the incidence of grade 3 or higher adverse events between the groups, and no grade 4 or 5 toxicities were reported.
Implications for Clinical Practice
These findings suggest that LFI may be a preferable approach for PORT in ESCC, particularly in achieving better locoregional control without significantly increasing treatment-related toxicities. The study underscores the importance of radiation field design in optimizing outcomes for patients undergoing postoperative radiotherapy for esophageal cancer.
