Powell, Chelsea

Abstract Objectives Society guidelines discourage biopsy of thymic epithelial tumours (TETs) due to the perceived risk of local seeding or pleural dissemination. However, few studies have evaluated this concern, and the true risk of preoperative biopsy remains unknown. Methods We queried the United States’ National Cancer Database for adults with localized TETs who underwent upfront R0 thymectomy 2004-2015. Use of preoperative biopsy over time was assessed with the Cochran-Armitage test. Postoperative outcomes were compared with chi-square and Wilcoxon rank sum tests. Overall survival (OS) was analysed with Kaplan-Meier and Cox proportional hazard methods. Results We identified 1056 patients. The median age was 61 years; 47% (492) were male. Use of preoperative percutaneous biopsy increased 2006-2015 from 18% to 33% (P < .001). Patients who underwent biopsy had larger tumours [median 6.6 vs 5.0 cm], more open operations [72% (150) vs 62% (331)] and regional lymphadenectomies [44% (118) vs 33% (250)], and a longer length of hospitalization (median 4 vs 3 days). Thirty-day mortality was similar between the groups. There was no difference in 10-year OS between the biopsy and no-biopsy groups [75% (95% CI 69%-82%) vs 76% (95% CI 73%-80%), P = .8]. After adjusting for age, sex, primary payor, histology, and tumour size, OS was similar between the biopsy and no-biopsy groups [AHR 0.97 (95% CI 0.72-1.29), P = .9]. Conclusions In this analysis of patients with localized TETs undergoing upfront R0 thymectomy, preoperative biopsy is not associated with worse OS. More study is needed to further explore whether biopsy increases risk of recurrence.