Background & objective: The recurrence rate in skull base is high for nasopharyngeal carcinoma (NPC) patients with cavernous sinus or/and sphenoid sinus involvement. This study was conducted to explore the impact of dose boost in skull base on the recurrence in skull base and survival of NPC patients with cavernous sinus or/and sphenoid sinus involvement.
Methods: A total of 120 stage T4 NPC patients with cavernous sinus or/and sphenoid sinus involvement proved by histopathology and computed tomography (CT) were treated in our hospital from Oct. 1996 to Nov. 1998. The irradiation dose was (71.55+/-3.09) Gy in nasopharynx and (58.95+/-6.16) Gy in neck. Of the 120 patients, 27 received irradiation (6-10 Gy) in skull base after radiotherapy (boost group), 93 did not receive irradiation in skull base (control group). Fifty-three patients, 41 in control group and 12 in boost group, received cisplatin-based chemotherapy for 1-3 cycles. The survival rates and the recurrence of the 2 groups were calculated by Kaplan-Meier method and log-rank test.
Results: The clinical characteristics of patients were similar in the 2 groups. The 1-, 3-, 5-year skull base control rates were significantly higher in boost group than in control group (100% vs. 93.4%, 91.8% vs. 76.4%, and 86.8% vs. 65.1%, respectively, P=0.045). The 1-, 3-, 5-year disease-freely survival rates were slightly higher in boost group than in control group (85.2% vs. 75.3%, 59.3% vs. 45.2%, and 51.9% vs. 31.2%, respectively, P=0.084). The median disease-freely survival time was longer in boost group than in control group (60 months vs. 30 months). The prevalences of irradiation-induced brain damage were 7.4% in boost group and 4.3% in control group with no significant difference (P=0.514).
Conclusion: Dose boost in skull base can reduce the recurrence of stage T4 NPC in skull base and tends to enhance the disease-freely survival rate for NPC patients with cavernous sinus or/and sphenoid sinus involvementû it is recommended to such patients.