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Comparative Effectiveness and Safety of Radiotherapy Treatments for Head and Neck Cancer

Slide: 13 of 36

Potential Advantages and Disadvantages of IMRT When Compared With 2DRT and 3DCRT

Potential benefits include the ability to deliver higher doses to the tumor, while sparing normal, surrounding tissues and, thereby, decreasing toxicity. Reducing the radiation dose to normal structures offers potential benefits, which include sparing of salivary gland tissue to reduce the severity of xerostomia (dryness of the mouth due to decreased salivary function) and reducing the dose to structures related to swallowing (e.g., pharyngeal constrictor muscles and the larynx). There are several disadvantages to IMRT. Patients receive a higher total-body dose of radiation. There also is an increased risk of a marginal miss; in which case, the eradication of the tumor may be unsuccessful. IMRT has been associated with decreased dose homogeneity. When compared to more conventional radiotherapy techniques, IMRT is more expensive and time consuming. Difficulties have also arisen in set-up reproducibility and patient immobilization, and it has been shown that variations in daily patient positioning and changes in patient anatomy (e.g., weight loss, tumor shrinkage) may result in significant dose perturbations when compared with the original treatment plan. Finally, there has been concern about variations in prescribed doses vs. what dose is actually delivered to the patient, and variations between medical institutions have raised concerns about the validity of comparing clinical outcomes for IMRT.