By John Otrompke
CHICAGO -- November 10, 2009 -- Patients treated with simultaneously integrated boost treatment using intensity-modulated radiation therapy (IMRT) experience better overall survival, disease-free survival, and local recurrence rates, as well as decreased dermatitis and better postoperative salivary function that those treated with conventional radiation.
"IMRT treatment was described as 'boosted' because we use 2 different doses in the same patient, who gets a dose of 2.12 gy to 1 part of their anatomy, while another part gets 1.8 gy," said Sebastien Clavel, MD, University of Montreal, Montreal, Quebec, on November 3 at the American Society of Therapeutic Radiology and Oncology (ASTRO) 51st Annual Meeting.
In the study, 249 patients with stage III and IV oropharyngeal carcinoma were treated between 2000 and 2007. Of these, 100 received IMRT, while 149 patients received conventional radiation therapy.
After a 33-month median follow-up, 95.4% of those treated with IMRT were still alive, compared with 75.8% of those in the conventional arm. Disease-free survival was 89.3% for the IMRT group, compared with 71.6% in the conventional radiation arm.
In addition, local control was 92.4% in the IMRT patients, compared with 85.3% in the conventional group.
"With the old technique, the rays were shooting from both sides, whereas with IMRT, the rays come from all directions," said Dr. Clavel. "When using IMRT, we also always give them a 3-mm margin with the skin, both of which result in fewer cases of dermatitis." IMRT patients experienced a 20% decrease in dermatitis grades 3 and 4.
"If we are able to treat the tumour with IMRT while avoiding the structure of the parotid gland, which produces saliva, the patients can live better, because more saliva is useful to protect the teeth, to eat, and swallow," he added, noting that only 8% of those treated with IMRT experience grade 3 or 4 xerostomia at 2 years following treatment, compared with 80% of those treated with conventional radiation.
Better salivary function was also associated with increased weight regain post operatively. "Patients lost 10% of their weight during treatment; while they did not gain all their weight back in the IMRT group, they were able to regain up to 50% more than those treated with conventional radiation," said Dr. Clavel.
[Presentation title: A Comparison of Simultaneously Integrated Boost Using Intensity-Modulated Radiation Therapy and Conventional Radiation Therapy in the Setting of Concomitant Carboplatin and 5-Fluorouracil for Locally Advanced Oropharyngeal Carcinoma. Abstract 69]
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