Important prognostic factors in patients with skull base erosion from nasopharyngeal carcinoma after radiotherapy

Purpose: To evaluate the long-term outcome and prognostic factors in patien ts with skull base erosion from nasopharyngeal carcinoma after initial radi otherapy (RT). Methods and Materials: From January 1985 to December 1986, 100 patients (71 males, 29 females) with a diagnosis of nasopharyngeal carcinoma were found on computed tomography (CT) to have skull base erosion. The mean age was 4 1 years (range 16-66). Ninety-six patients had World Health Organization ty pe III undifferentiated carcinoma, and 4 had type L The metastatic workup, including chest radiography, liver ultrasound scanning, and liver function test was negative. All patients underwent external beam RT (EBRT) alone to 66-80 Gy during 6-8 weeks. A daily fraction size of 2 Gy was delivered usin g Co-60 or a linear accelerator. No patient received chemotherapy. All pati ents were followed at regular intervals after irradiation. The median follo w-up was 22.3 months (range 2-174). Survival of the cohort was computed by the Kaplan-Meier method. The potential prognostic factors of survival were examined. Multivariate analyses were performed using the Cox regression mod el. Results: The 1, 2, 5, and 10-year overall survival rate for the cohort was 79%, 41%, 27%, and 13%, respectively. However, the subgroup of patients wit h both anterior cranial nerve (I-VIII) and posterior cranial nerve (IX-XII) involvement had a 5-year survival of only 7.7%. A difference in the time c ourse of local recurrence and distant metastasis was observed. Both local r ecurrence and distant metastasis often occurred within the first 2 years af ter RT. However, local relapse continued to occur after 5 years. In contras t, no additional distant metastases. were found after 5 years. The causes o f death included local recurrence (n = 59), distant metastasis (n = 21), bo th local recurrence and distant metastasis (n = 1), and unrelated causes (n = 5). After multivariate analysis, complete recovery of cranial nerve invo lvement cranial nerve palsy, and headache after irradiation were found to b e independent prognostic factors in this cohort. Conclusions: We present one of the longest follow-ups of patients with naso pharyngeal carcinoma invading the skull base. Our results demonstrate the i mportance of cranial nerve involvement, recovery of headache, and cranial n erve palsy. These factors should be carefully evaluated from the history, p hysical examination, and imaging studies. A subgroup of patients with skull base involvement had long-term survival after RT alone. The findings of th is study are important as a yardstick against which more aggressive strateg ies, such as combined radiochemotherapy and altered fractionation RT can be compared. (C) 2001 Elsevier Science Inc.