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Targeted radiation for esophageal cancer therapy reduces toxicity without increasing recurrence
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Involved-field irradiation therapy reduced toxicity without increasing loco-regional lymph node recurrence compared with elective nodal irradiation among patients with locally advanced esophageal cancer, according to prospective, randomized controlled study results presented at the ASTRO Annual Meeting.
Chemoradiation is the standard of care for locally advanced esophageal cancer. Elective nodal irradiation — or radiation to the tumor and lymph nodes, including uninvolved lymph nodes in the region around the tumor — is a radiation modality used to treat esophageal squamous cell carcinoma (ESCC); however, its use is controversial because it delivers higher irradiation and leads to higher rates of toxicity.
Tao Li, MD, PhD, vice chair of the department of radiation oncology at the Sichuan Cancer Hospital and Institute in Chengdu, China, and colleagues sought to evaluate the feasibility of reducing the nodal irradiation volume by comparing elective nodal irradiation to involved-field irradiation, which targets only the involved lymph nodes.
“Elective nodal irradiation is the most commonly used type of radiation therapy for treating esophageal cancer, but its toxicity and side effects have been criticized,” Li said in a press release. “Researchers have suggested decreasing the nodal irradiation volume with the use of involved-field irradiation, yet prior to this study its potential advantages had only been measured in smaller trials.”
The trial included 110 patients with esophageal cancer treated in several institutions across China — where the disease is much more prevalent than in the U.S. — between April 2012 and November 2014. All patients had inoperable, newly diagnosed stage II-III thoracic ESCC and were created with concurrent chemoradiotherapy and image-guided radiotherapy.
Researchers randomly assigned patients to receive elective nodal irradiation (n = 56) or involved-field irradiation (n = 54).
Toxicity and local-regional recurrence in the lymph nodes served as the study’s primary endpoint. Secondary endpoints included OS and distant failure.
After a median follow-up of 20 months, significantly fewer patients assigned involved-field irradiation experienced grade 2 or worse radiation esophagitis (20.4% vs. 26.8%; P = .001) and radiation pneumonitis (12.9% vs. 26.8%; P = .011).
There were no significant differences in rates of loco-regional lymph nodal recurrence (27.9% vs. 20.4%), distant failure (12.5% vs. 13%), 1-year OS (89.2% vs. 88.3%) or 2-year OS (64.2% vs. 55.6%) between the elective nodal irradiation and involved-field irradiation arms.
“We anticipated that involved-field irradiation could significantly decrease toxicity such as radiation pneumonitis and radiation esophagitis, but we were initially uncertain if involved-field irradiation might increase the loco-regional lymph nodal recurrence rates, distant failure and OS,” Li said in the release. “The mid-term results of our trial show that involved-field irradiation is an acceptable and toxicity-minimizing method of treatment for thoracic ESCC. This is a significant discovery for future esophageal cancer radiotherapy care.” – by Anthony SanFilippo
For more information: Li T, et al. Abstract 7. Presented at: ASTRO Annual Meeting; Oct. 18-21, 2015; San Antonio, Texas.
Disclosure: HemOnc Today was unable to confirm the researchers’ relevant financial disclosures at the time of reporting.Perspective
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Jing Zeng, MD
Li and colleagues present an important study on the appropriate size of radiation treatment fields in definitive chemoradiation for esophageal squamous cell carcinoma. Current treatments have significant side effects, with local recurrence rates of around 50% with "elective" nodal radiation.
By focusing on only treating lymph nodes that are clearly involved with tumor, involved field radiation can shrink radiation fields, which can decrease toxicity. However, based on surgical data, most metastatic nodes in esophageal cancer are normal in size (< 1 cm) and appear similar to uninvolved nodes on imaging.
Although the results of this study are interesting and warrant further attention, it is important to recall that this is an interim analysis with short follow-up, and only 110 patients have been treated out of 320 estimated total patients needed for the trial. The radiation dose used in the study is higher than usual doses used in the US — 60 Gy to 66 Gy to the gross tumor volume was used in the study, whereas U.S. doses typically range from 45 Gy to 50.5 Gy. The local failure rates are only 14%, vs. the 50% usually seen in U.S. studies. The Western patient population also tends to be mostly adenocarcinoma in the lower esophagus, instead of the squamous cell carcinoma treated in this study.
In conclusion, we look forward to the mature results of this study, but would not change our current practice pattern based on this preliminary analysis.Click Here to Manage Email Alerts