Krol A D G, le Cessie S, Snijder S, Kluin-Nelemans J C, Kluin P M, Noordijk E M
Department of Clinical Oncology, Leiden University Medical Centre, Leiden, The Netherlands.
Ann Oncol. 2003 Jan;14(1):131-9. doi: 10.1093/annonc/mdg004.
The definition of primary extranodal non-Hodgkin's lymphoma (NHL) is a controversial issue, especially in patients where both nodal and extranodal sites are involved.
The impact of different definitions of primary extranodal NHL on incidence and prognosis is explored using data from a population-based NHL registry.
Using liberal criteria, 389 (34%) cases were classified as primary extranodal NHL. Overall survival (OS) rates of nodal and extranodal NHL patients defined this way were comparable; however, extranodal NHL patients had a better disease-free survival (DFS). When strict criteria were applied, 231 cases (20%) were classified as primary extranodal NHL. OS and DFS rates of extranodal NHL patients defined this way were superior to nodal NHL patients; however, the difference in OS was reversed after correction for differences in International Prognostic Index and malignancy grade.
This study illustrates the selection bias that is introduced when a strict definition of primary extranodal NHL, that excludes cases with disseminated disease, is used. Patients with primary extranodal NHL were found to have a superior DFS, irrespective of which definition of primary extranodal NHL was used.
原发性结外非霍奇金淋巴瘤（NHL）的定义是一个有争议的问题，尤其是在结内和结外部位均受累的患者中。
利用基于人群的NHL登记处的数据，探讨原发性结外NHL的不同定义对发病率和预后的影响。
采用宽松标准时，389例（34%）病例被归类为原发性结外NHL。以这种方式定义的结内和结外NHL患者的总生存率（OS）相当；然而，结外NHL患者的无病生存率（DFS）更好。采用严格标准时，231例（20%）病例被归类为原发性结外NHL。以这种方式定义的结外NHL患者的OS和DFS率优于结内NHL患者；然而，在校正国际预后指数和恶性肿瘤分级差异后，OS差异逆转。
本研究说明了当使用排除播散性疾病病例的原发性结外NHL严格定义时所引入的选择偏倚。无论采用哪种原发性结外NHL的定义，原发性结外NHL患者的DFS均较好。
