Propensity score-based comparison of long-term outcomes with 3-dimensional conformal radiotherapy vs intensity-modulated radiotherapy for esophageal cancer

Steven H Lin, Lu Wang, Bevan Myles, Peter F Thall, Wayne L Hofstetter, Stephen G Swisher, Jaffer A Ajani, James D Cox, Ritsuko Komaki, Zhongxing Liao, Steven H Lin, Lu Wang, Bevan Myles, Peter F Thall, Wayne L Hofstetter, Stephen G Swisher, Jaffer A Ajani, James D Cox, Ritsuko Komaki, Zhongxing Liao

Abstract

Purpose: Although 3-dimensional conformal radiotherapy (3D-CRT) is the worldwide standard for the treatment of esophageal cancer, intensity modulated radiotherapy (IMRT) improves dose conformality and reduces the radiation exposure to normal tissues. We hypothesized that the dosimetric advantages of IMRT should translate to substantive benefits in clinical outcomes compared with 3D-CRT.

Methods and materials: An analysis was performed of 676 nonrandomized patients (3D-CRT, n=413; IMRT, n=263) with stage Ib-IVa (American Joint Committee on Cancer 2002) esophageal cancers treated with chemoradiotherapy at a single institution from 1998-2008. An inverse probability of treatment weighting and inclusion of propensity score (treatment probability) as a covariate were used to compare overall survival time, interval to local failure, and interval to distant metastasis, while accounting for the effects of other clinically relevant covariates. The propensity scores were estimated using logistic regression analysis.

Results: A fitted multivariate inverse probability weighted-adjusted Cox model showed that the overall survival time was significantly associated with several well-known prognostic factors, along with the treatment modality (IMRT vs 3D-CRT, hazard ratio 0.72, P<.001). Compared with IMRT, 3D-CRT patients had a significantly greater risk of dying (72.6% vs 52.9%, inverse probability of treatment weighting, log-rank test, P<.0001) and of locoregional recurrence (P=.0038). No difference was seen in cancer-specific mortality (Gray's test, P=.86) or distant metastasis (P=.99) between the 2 groups. An increased cumulative incidence of cardiac death was seen in the 3D-CRT group (P=.049), but most deaths were undocumented (5-year estimate, 11.7% in 3D-CRT vs 5.4% in IMRT group, Gray's test, P=.0029).

Conclusions: Overall survival, locoregional control, and noncancer-related death were significantly better after IMRT than after 3D-CRT. Although these results need confirmation, IMRT should be considered for the treatment of esophageal cancer.

Conflict of interest statement

Disclaimers: The authors have no conflicts of interest to report.

Figures

Figure 1. Overall and disease-specific survival of… — **Figure 1. Overall and disease-specific survival of 3DCRT and IMRT treated patients**
A. IPW adjusted Kaplan-Meier estimates of the overall survival time curves, with 95% confidence intervals. B. IPW adjusted Kaplan-Meier estimates of cancer-specific survival, with 95% confidence intervals. C. IPW adjusted Kaplan-Meier estimates of the LRR free survival curves, with 95% confidence intervals. D. IPW adjusted Kaplan-Meier estimates of the distant metastatic free survival curves, with 95% confidence intervals.

Figure 2. Local-regional recurrence in 3DCRT and… — **Figure 2. Local-regional recurrence in 3DCRT and IMRT treated patients stratified according to surgery**
A. IPW adjusted Kaplan-Meier estimates of the LRR time in the patients who had surgery after chemoradiotherapy. B. IPW adjusted Kaplan-Meier estimates of the LRR time in definitively treated patients with chemoradiotherapy.

Figure 3. Comparison of radiation technique in… — **Figure 3. Comparison of radiation technique in the patterns of local-regional failure in the definitively treated esophageal cancer patients**
IPW adjusted Kaplan-Meier estimates of the time-to-recurrence in the A) primary, B) in-field nodal, or C) outfield nodal disease sites.

Figure 4. Cumulative Incidence Function for all… — **Figure 4. Cumulative Incidence Function for all cause mortalities of 3DCRT and IMRT treated patients**
A. Overall cumulative incidence function for the various causes of deaths. B. Cumulative incidence function of each death type for the two treatment groups.

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Source: PubMed

Propensity score-based comparison of long-term outcomes with 3-dimensional conformal radiotherapy vs intensity-modulated radiotherapy for esophageal cancer

Abstract

Conflict of interest statement

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