Purpose: The purpose of this study was to differentiate the patterns of nasal fossa involvement in nasopharyngeal carcinoma (NPC) and to clarify its prognostic influence on local control and survival after radiation therapy.
Methods and materials: Between November 1989 and July 1991, 218 patients with histologically proven local-regional NPC were treated with radiotherapy following the protocol at the Department of Radiation Oncology, Cancer Hospital, Shantou University School of Medicine. All patients had pretreatment CT scans. Fiberoptic endoscopic examination was performed every week during treatment and at the time of every follow-up visit to define the initial extent of disease and to evaluate treatment response. No chemotherapy or brachytherapy was given.
Results: Of the 218 patients, 87 had nasal involvement. Sixty of them had a pattern of mucosal infiltration (MI), another 27 had an exophytic protruding (EP) component. The likelihood of residual disease after irradiation, the local relapse rate, 5-year freedom from progression rate (FFP), and death rate associated with local relapse (DRALR) of MI and EP were 36.7% vs. 3.7%, 30.0% vs. 7.4%, 26.7% vs. 51.8%, and 25.0% vs. 3.7% with p<0.004, p<0.005, p<0.02, and p<0.03, respectively. Multivariate analysis in this selected group demonstrated that infiltration of nasal fossa mucosa was an independent prognostic factor on primary control and freedom from progression.
Conclusion: Differentiation of nasal fossa involvement according to MI or EP is of value in predicting the outcome of treatment. We suggest that only the MI group should be considered as nasal involvement in the staging of NPC.