Nasopharyngeal carcinoma--a review of radiotherapy techniques.
With modern megavoltage external X-ray treatment for nasopharyngeal carcinoma, results have improved but late sequelae, which are more often associated with the treatment of advanced tumours or multiple courses of external treatment, have also surfaced. Life-threatening complications include temporal lobe necrosis and hypothalamic-pituitary dysfunction. As CT scanning is superior to conventional radiography in tumour mapping, a new dedicated working staging system, catering for cross-sectional imaging parameters, is proposed for a prospective, multi-centre exercise to finalise on a badly needed common system. With it, case selection for more conservative (to minimise complications) or intensified treatments is facilitated. Intracavitary radiation has now been developed well enough for the nasopharynx. For earlier cases, based on the new staging system, this method has the potential to complement a "sub-radical" external treatment dose designed to minimise complications. A multi-centre trial is indicated. To reach cancericidal doses for the more advanced tumours coming very close to vital structures, extra machine time, though precious, is fully justified so that smaller treatment fractions delivered with facial shells for accurate reproduction of precise machine geometry and field geography can be implemented. Otherwise, subsequent management of possible serious treatment complications may cost more than the treatment itself. Various possible complications of radiotherapy and avoidance and management are outlined.
Tsao
S Y
SY
Department of Therapeutic Radiology, Singapore General Hospital.
D001918:Brachytherapy / Q000295:instrumentation; D006801:Humans; D008953:Models, Anatomic; D009303:Nasopharyngeal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D009336:Necrosis; D009367:Neoplasm Staging; D011832:Radiation Injuries / Q000209:etiology; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation*; D013702:Temporal Lobe / Q000473:pathology / Q000528:radiation effects