Repeat biopsy of primary disease negatively affects the outcome of patients with nasopharyngeal cancer treated with definitive intensity-modified radiotherapy: a cohort analysis of 795 patients

Objective: To determine whether pretreatment repeat biopsy of nasopharynx is associated with an impaired outcome in nasopharyngeal carcinoma patients in an intensity-modified radiotherapy era. Methods: We performed a retrospective data review of the association between pretreatment nasopharyngeal biopsy and outcomes for all nasopharyngeal carcinoma patients treated at our center between January 2007 and December 2011. Of the 720 patients enrolled, 693 (96.3%) were diagnosed after initial biopsy and 27 (3.7%) after repeat biopsy. Five-year cancer-specific survival, disease-free survival and distant metastasis-free survival for the two groups were compared using univariate and multivariate analyses to evaluate the effects of repeat biopsy on the outcome. Results: Five-year estimated cancer-specific survival (75.9 vs. 88.5%, P = 0.045) and disease-free survival (63.3 vs. 77.1%, P = 0.041) were significantly poorer in the repeat biopsy group than the initial biopsy group. After adjustment for other prognostic factors (age, gender, T and N stage), pretreatment biopsy remained independently associated with poorer both 5-year cancer-specific survival and disease-free survival. The hazard ratios for cancer-specific survival and disease-free survival in the repeat biopsy group were 2.73 (95% confidence interval 1.09-6.82) and 2.22 (95% confidence interval 1.12-4.37) compared with the initial biopsy group (reference), respectively. The repeat biopsy group also had a higher risk of distant failure compared with the initial biopsy group (hazard ratio 2.82, 95% confidence interval 1.22-6.51, P = 0.015). Conclusion: Pretreatment repeat biopsy of nasopharynx has a detrimental effect on survivals of nasopharyngeal carcinoma patients, which may be partly due to an increased frequency of distant metastasis.