Less salivary gland toxicity in patients treated with IMRT for oropharyngeal cancer

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BOSTON—Intensity-modulated radiation therapy (IMRT) for patients with early-stage oropharyngeal cancer showed a reduction in long-term salivary toxicity, while achieving good tumor control, according to research from the Radiation Therapy Oncology Group (RTOG) presented Wednesday at the 50th Annual Meeting American Society for Therapeutic Radiology and Oncology (ASTRO).

RTOG, a National Cancer Institute-funded national clinical trials group, is a clinical research component of the American College of Radiology (ACR).

RTOG launched its phase I/II trial (RTOG 0022) to determine whether standardized dose and target definitions for IMRT could be accomplished in a multicenter setting. It enrolled 69 patients in the study from February 2001 through January 2005 from 14 academic and community institutions in the United States and Canada. 

According to the researchers, a two-year local-regional control rate of 91 percent and a 49 percent rate of acute salivary gland toxicity (Grade 2) were reported, compared with 80 and 84 percent in the same patient population from the RTOG database. They said that the rate of salivary gland toxicity dropped to 23 percent at one year and 13 percent at two years. 

The authors wrote that the evaluable patients who, at central review of their treatment plan, were found to have a major variation in their radiotherapy treatment plan had a significantly higher rate of local-regional failure than patients who were treated according to protocol (50 vs. 6 percent).  

“This study was the work of many physicians and physicists to establish the rules for IMRT doses and quality assurance, at a time, 1999-2000, when IMRT was in its infancy and very few institutions started treating patients with it,” said the study’s lead author Avraham Eisbruch, MD, from the University of Michigan Health Systems in Ann Arbor, Mich.

The researchers noted that all institutions participating in the trial were pre-approved for IMRT by the Image-guided Therapy QA Center at Washington University in St. Louis.