Salvage therapy for recurrent nasopharyngeal carcinoma (rNPC) is required in 9-40% of patients. Diagnosis of rNPC is difficult, because up to 20% of all treated patients develop osteoradionecrosis (ORN) leading to similar symptoms. Conventional or office-based biopsies (OBB) are often unreliable for diagnosis. Moreover, imaging and OBB often cannot estimate the burden of recurrent disease in the presence of concurrent ORN.
Our primary objective was to compare a novel, anatomic intraoperative mapping biopsy (IMB) technique to the traditional OBB for diagnosing rNPC. Our secondary objective was to introduce IMB as a tool for anatomical mapping in order to determine rNPC resectability.
A retrospective cohort review of patients, who presented with suspected rNPC from 2007-2018 was conducted in our single, tertiary care center. Patients meeting inclusion criteria for the study had a history of NPC treated with either primary radiation with or without chemotherapy and underwent OBB for suspected recurrence followed by IMB. IMB is a standardized protocol for CT-navigated, anatomical intraoperative nasopharyngeal sampling, which helps delineate potential recurrent tumor. All patients underwent contrast enhanced MRI and PET/CT before undergoing IMB.
Twenty-three consecutive patients met the inclusion criteria and were incorporated into the analysis. Fifteen patients (65.2%) were diagnosed with rNPC during the follow up period. IMB demonstrated sensitivity of 86.7% (95%CI: 59.5-98.3%) and specificity of 100%. In contrast, OBB sensitivity was 53.3% (95%CI: 26.6-78.7%) and specificity of 25% (95%CI 3.19-65.09). The difference in specificity was statistically significant with McNemar’s test (p<0.05).
Ten patients undergoing IMB had negative results, and two of these were eventually found to be positive for rNPC (False negative rate of 20%). In contrast, there were 9 OBB tests that had negative results, with 7 confirmed to have rNPC (False negative rate of 78%).
Four patients were deemed unresectable on IMB. However, 9 patients were candidates for resection, and consequently underwent nasopharyngectomy with clear surgical margins. The nasopharyngectomy specimen positivity correlated with anatomic sampling on IMB.
Despite the modest sample size, our study demonstrates the significant value in anatomic, surgeon-guided biopsies for diagnosis and treatment planning of suspected rNPC. IMB gives the surgeon a higher chance of correct diagnosis by targeting the high-risk areas for recurrence in the nasopharynx. Another advantage is simultaneous evaluation for potential resectability or re-irradiation planning. Therefore, IMB should be included into the armamentarium of surgeons for diagnosis, and potential treatment planning of patients with suspected rNPC.