Patterns of failure in carcinoma of the nasopharynx: I. Failure at the primary site.

Between 1970 and 1980, we treated 107 previously untreated patients with biopsy proven carcinoma of the nasopharynx by megavoltage external radiation therapy to the primary site, base of the skull and both sides of the neck. Fifty-three percent of the patients had T4 primaries and 87% had Stage IV disease. The histology was poorly differentiated, undifferentiated or anaplastic carcinoma in 81% of the patients, and well differentiated or moderately well differentiated epidermoid carcinoma in 19%. The dose of irradiation to the primary site ranged from 5700 to 7700 rad. Fifty-five patients have suffered relapse of the cancer, 33 of whom (60%) relapsed at the primary site. Seventy-two percent of the relapses at the primary site appeared within two years after treatment and 91 percent within 3 years. Median survival following relapse at the primary site was 10 months. Those patients who received a dose to the primary between 5700 and 6700 rad had a lower rate of local control than those who received a dose between 6700 and 7700 rad. However, regardless of the dose, those patients whose radiation therapy was interrupted (for whatever reason) for a total of three weeks or longer had poorer local control than those patients whose treatment was not so interrupted. The highest rate of local control (84%) was observed in those patients who did not have such interruptions and received a dose of 6700-7700 rad to the primary. Improved local control with the higher doses was especially striking for T4 primaries, suggesting a dose-response relationship. The local control rate did not appear to be significantly influenced by age, sex, birthplace or histology. These data suggest that a high rate of local control is possible in carcinoma of the nasopharynx, even with T4 disease, if a sufficiently high dose of radiation therapy is delivered without undue interruptions.