Published online Aug 27, 2026. doi: 10.4240/wjgs.117559
Revised: February 8, 2026
Accepted: April 1, 2026
Published online: August 27, 2026
Processing time: 211 Days and 23.2 Hours
Postoperative radiotherapy reduces local recurrence in locally advanced colorectal cancer, but its efficacy depends on accurate target volume delineation. This study assessed the impact of delineation accuracy on treatment outcomes.
To investigate the impact of target volume delineation accuracy on treatment out
Clinical data of 218 colorectal cancer patients who underwent radical surgery followed by adjuvant radiotherapy at our hospital from January 2019 to December 2022 were retrospectively analyzed. Patients were divided into an accurate target volume group (126 cases) and an inaccurate target volume group (92 cases) based on target delineation quality. Survival outcomes, recurrence patterns, and adverse events were compared between the two groups. The Kaplan-Meier method was used for survival analysis, the Log-rank test for comparing group differences, and the Cox proportional hazards regression model for analyzing independent prog
The median follow-up was 38 months. The 3-year local control, regional control, disease-free survival, and overall survival were 92.1%, 94.4%, 83.6%, and 89.2% in the accurate target volume group, respectively, compared to 78.3%, 81.5%, 66.8%, and 72.5% in the inaccurate target volume group (P < 0.05). Recurrence pattern analysis showed that 75.8% of recurrences occurred in marginal or out-of-field regions in the inaccurate target volume group, compared to 34.8% in the accurate target volume group (P = 0.002). Multivariate analysis revealed that target volume delineation accuracy was an independent prognostic factor affecting disease-free survival (hazard ratio = 2.186, 95% confidence interval: 1.304-3.665, P = 0.003) and overall survival (hazard ratio = 2.398, 95% confidence interval: 1.334-4.311, P = 0.004). The incidence of grade ≥ 2 late intestinal adverse events was 8.7% in the accurate target volume group, lower than 18.5% in the inaccurate target volume group (P = 0.033).
Target volume delineation accuracy is an independent prognostic factor affecting the efficacy and safety of postoperative radiotherapy for colorectal cancer. Accurate target volume delineation can improve locoregional control and survival outcomes, reduce marginal and out-of-field recurrence, and decrease late adverse events. Clinical practice should strengthen quality control of target volume delineation, follow standardized guidelines, adopt multidisciplinary collaboration models, and ensure accuracy of target volume delineation.
Core Tip: Accurate target volume delineation is essential for effective postoperative radiotherapy in colorectal cancer. This study demonstrates that inaccurate target definition leads to markedly higher marginal and out-of-field recurrence, inferior disease-free and overall survival, and increased late intestinal toxicity. Target accuracy emerged as an independent prognostic factor comparable to nodal stage and margin status. These findings underscore the need for standardized delineation guidelines, multidisciplinary review, and advanced imaging integration to ensure optimal tumor coverage and minimize treatment failures.