Patterns of failure in nasopharyngeal cancer treated with megavoltage irradiation.

From 1976 to 1982, 78 patients with nasopharyngeal cancer (NPC) were treated with definitive megavoltage irradiation in accordance with a uniform protocol. The results of treatment were analyzed and prognostic factors reviewed. The incidence of primary failures was directly related to the extent of nasopharyngeal disease, since the relapse rate was 11% in T1T2 patients compared with 37.5% in T3T4 patients. Similarly, failure in the neck correlated with the N stage, being negligible for N0 and N1, while 35.7% for N3. The presence of bulky cervical nodes was associated with a higher risk for metastases: hematogenous dissemination occurred in 50% of N3B patients. The histology pattern seemed to significantly affect the ultimate outcome of patients with NPC, since disease-free survival was 65.5% in patients with a diagnosis of undifferentiated carcinoma (UC) and 23.8% in patients with squamous cell carcinoma (SC). The major cause of poor survival in this latter patient group was not only a higher recurrence rate of both primary and nodal disease but a greater incidence of distant metastases as well.