3601 - Patterns of Failure and Disease Recurrence in Nasopharyngeal Cancer: A Five-Year Analysis in an EBV Endemic Population at Pakistan's Largest Cancer Center

Purpose/Objective(s): Nasopharyngeal carcinoma (NPC) is an Epstein–Barr virus (EBV) associated malignancy with a high incidence in endemic regions like Pakistan with diverse histopathology and patterns of failure. We aimed to evaluate patterns of failure, disease recurrence, and survival outcomes in EBV positive NPC patients treated at Pakistan’s largest tertiary cancer center.

Materials/Methods: We retrospectively analysed adult patients with biopsy-proven, locally advanced, non-metastatic NPC treated with definitive intent between Jan-2018 and Dec-2023. Patients were treated with 2 cycles of induction chemotherapy (Cisplatin and Gemcitabine), followed by intensity modulated radiotherapy (IMRT) with concurrent Cisplatin. Patterns of failure were recorded, and survival outcomes including overall survival (OS), recurrence-free survival (RFS), local relapse free survival (LRFS), and distant relapse free survival (DRFS) were estimated using the Kaplan–Meier method.

Results: 265 patients were included with a median age of 45 years (28-67), 190 (71.7%) were male. 140 (52.8%) had T3/T4 disease and 203 (76.6%) had N2/N3 disease. Most patients had undifferentiated keratinizing histology (n=190). 253 (98.1%) patients received induction chemotherapy and 253 (95.5%) received concurrent chemotherapy. All patients were treated with IMRT. With a median follow up of 64 months, 183 (69.1%) patients were disease-free while 82 (30.9%) developed recurrence. 20 patients had local, 5 had regional, and 1 had both local and regional recurrence. 61 developed distant recurrence (Table 1). Sites of distant recurrence were osseous (n=14), visceral (n=11), non-regional node only (n=1), combined visceral and osseous (n=16), combined visceral and nodal (n=3), and multiple sites in 14 patients. Local control was satisfactory; distant metastases, particularly in the osseous and visceral regions, remained the predominant pattern of failure. Median OS was 64.8 months (5-year: 60.9%; 95% CI, 52.3%–71.1%). Median RFS was 68 months (5-year: 55.0%; 95% CI, 47.5%–64.8%). Mean LRFS was 63.0 months (5-year: 82.5%; 95% CI, 76.2%–89.3%), and mean DRFS was 53.75 months (5-year: 65.7%; 95% CI, 57.4%–75.2%)

Conclusion: In this EBV-endemic Pakistani cohort, IMRT-based multimodality treatment achieved excellent locoregional control; however, distant metastasis remained the predominant pattern of failure and a major determinant of long-term survival. These findings underscore the need for improved systemic strategies and biomarker-guided risk stratification to reduce distant relapse and optimize outcomes in endemic NPC populations.