At a median follow-up of 20 months, data showed that IFI resulted in significantly decreased radiation pneumonitis (inflammation of the lungs) and radiation esophagitis (inflammation of the lining of the esophagus). Grade = 2 radiation pneumonitis in the ENI group was 26.8 percent, compared to 12.9 percent in the IFI group (p = 0.011); and the rate of radiation esophagitis was 37.5 percent in the ENI group compared to 20.4 percent in the IFI group (p = 0.001).

No significant differences in the loco-regional lymph nodal recurrence rate were observed between the two groups. The ENI group experienced a 17.9 percent loco-regional lymph nodal recurrence, compared to the IFI group, which experienced a 20.4 percent loco-regional lymph nodal recurrence (p = 0.819).


Evaluation of distant failure rates (measurement of whether the cancer appeared in other areas other than the original tumor site), indicated a positive result with no difference between the two groups. The ENI group had a 12.5 percent distant failure rate and the IFI group had a 13 percent distant failure rates (p = 0.465).

The two groups achieved similar one-year and two-year OS rates. The one-year OS rate was 89.2 percent for the ENI group and 88.3 percent for the IFI group (p = 0.431); and the two-year OS rates was 64.2 percent for the ENI group, compared to 55.6 percent for the IFI group (p = 0.857).

"Elective nodal irradiation (ENI) is the most commonly used type of RT for treating esophageal cancer, but its side effects and toxicity have been criticized," said Tao Li, MD, PhD, lead author of the study and vice chairman of the department of radiation oncology at Sichuan Cancer Hospital and Institute. "Researchers have suggested decreasing the nodal irradiation volume with the use of IFI, yet prior to this study its potential advantages had only been measured in smaller trials. We anticipated that IFI could significantly decrease toxicity such as radiation pneumonitis and radiation esophagitis, but were initially uncertain if IFI might increase the loco-regional lymph nodal recurrence rates, distant failure and overall survival. The mid-term results of our trial show that IFI is an acceptable and toxicity-minimizing method of treatment for thoracic ESCC. This is a significant discovery for future esophageal cancer radiotherapy care."

The abstract, "Involved-Field Irradiation vs Elective Nodal Irradiation for Locally Advanced Thoracic Esophageal Squamous Cell Carcinoma: A Comparative Interim Analysis of Clinical Outcomes and Toxicities (NCT01551589, CSWOG-RTOG 002)," will be presented in detail during the plenary session at ASTRO's 57th Annual Meeting at 2:25 p.m. Central time on Monday, October 19, 2015. To speak with Dr. Li, please call Nancy Mayes in ASTRO's Press Office at the Henry B. González Convention Center, in San Antonio on October 18 – 21, 2015 at 210-258-8104 or 210-258-8105, or email press@astro.org.

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