Interstitial-implant radiotherapy in upper-aerodigestive-tract malignancy

In the treatment of upper-aerodigestive-tract malignancy, interstitial-implant radiotherapy differs in several physical and biologic respects from conventional external-beam therapy: unlike external-beam therapy, it can deliver a high central dose with a rapid fall-off, which overcomes the central hypoxic resistance effect and yet greatly improves normal tissue tolerance. External-beam and interstitial-implant therapy can also be combined to the patient's benefit; in many cases, this combination offers advantages over external-beam therapy alone, preoperative external-beam therapy, or aggressive surgery. The recent upsurge of interest in this modality has come about because of three developments: more suitable radioactive sources, after-loading, and computerized dosimetry. The early results in upper-aerodigestive-tract malignancy, both as primary and as salvage therapy, are promising; but the precise role of this treatment in our therapeutic armamentarium remains to be established.