HOW SUCCESSFUL IS HIGH-DOSE (GREATER-THAN-OR-EQUAL-TO-60 GY) REIRRADIATION USING MAINLY EXTERNAL BEAMS IN SALVAGING LOCAL FAILURES OF NASOPHARYNGEAL CARCINOMA

Purpose: To evaluate the efficacy of high-dose (greater than or equal to 60 Gy) reirradiation using mainly external beams in salvaging local failures of nasopharyngeal carcinoma (NPC) after modern primary radic al radiotherapy that delivered radical dose-to-target volumes defined by CT scan. Methods and Materials: Nine hundred and three patients wit h nondisseminated NPC whose primary radical radiotherapy was administe red between 1984 and 1989 inclusive were studied. One hundred and seve nty-six had local failures comprising 9 persistences and 167 recurrenc es. In 10 patients the local failures mere preceded or accompanied by (within 2 months) distant metastases, and these were given supportive treatment or palliative radiotherapy in low dose (<60 Gy) if symptomat ic. Most of the rest (123 of 166) mere treated with either reirradiati on to high dose (greater than or equal to 60 Gy) using mainly external photon beams (n = 103) or nasopharyngectomy with/without radical neck dissection with/without postoperative radiotherapy (n = 20). The rema inder (n = 43) received only palliative treatments because of poor gen eral condition and/or patients' refusal of radical treatments. The pri mary radiotherapy was planned on the basis of target volumes defined b y CT scan and given to a standard nasopharyngeal dose of 62.5 Gy/29 fr actions/6 weeks. In the presence of parapharyngeal involvement, an add itional boost of 20 Gy/10 fractions/2 weeks was given via a posterior oblique photon beam, If local residual tumors were diagnosed at 4-6 we eks after the completion of external radiotherapy, an additional boost of 24 Gy/3 fractions/15 days was given by intracavitary intubation. F or the local failures given high-dose reirradiation, the target volume was defined by CT scan and treated by a two-field or a three-field ph oton arrangement with or without additional dose supplement by intraca vitary intubation. Nasopharyngectomy was performed via the transcervic o-mandibulo-palatal approach or the maxillary swing approach. Radical neck dissection was only performed for the clinically evident nodal fa ilures. Results: With a median follow-up of 20 months (range 2.5-81 mo nths) since the diagnosis of local failure, the actuarial 5-year overa ll survival, further relapse-free survival and free-from-local-tumor r ates were 9.4, 11.5, and 18.7%, respectively, for the 123 patients tre ated by either high-dose reirradiation (n = 103) or nasopharyngectomy (n = 20). Palliatively treated patients (n = 43) had a survival compar able to patients whose local failures were preceded or accompanied by distant metastasis (n = 10). Reirradiation to high dose (greater than or equal to 60 Gy) mainly by external photon beams achieved a 5-year o verall survival of 7.6% and 5-year local control of 15.2% with signifi cant complications. Radiation-induced temporal lobe encephalopathy was radiologically evident in 21 patients (20.4%), and 13 of these 21 pat ients were symptomatic. It could have been the cause of death in three patients who also suffered from uncontrolled local tumor. Significant morbidity was also associated with the other frequent radiation compl ications, including xerostomia, trismus, and deafness. Uni-and multiva riate analyses indicated that brief initial disease-free interval betw een completion of primary radiotherapy and diagnosis of local failures and advanced recurrent T-stage and recurrent N-stage were significant prognosticators predicting poor survival and/or further local failure after reirradiation. These patients were unlikely to benefit from the treatment. Nasopharyngectomy (+/-neck dissection +/-postoperative rad iotherapy) was associated with earlier recurrent T-stages (mostly rT1 and rT2) and better survival and local control than reirradiation. How ever, restricting the comparison to rT1 and rT2 still demonstrated the superior results in favor of nasopharyngectomy, which could not be ex plained by the selection of less advanced lesions or patients with bet ter performance status for surgery. Conclusion: After modern primary r adical radiotherapy for NPC, local failures can seldom be salvaged by reirradiation to high dose (greater than or equal to 60 Gy) using main ly external beams, and morbidity is significant and outweighs the bene fit. Alternative methods for salvage such as nasopharyngectomy in suit able cases should be considered. (C) 1998 Elsevier Science Inc.