Primary extranodal non-Hodgkin's lymphoma (NHL): the impact of alternative definitions tested in the Comprehensive Cancer Centre West population-based NHL registry

Ann Oncol. 2003 Jan;14(1):131-9. doi: 10.1093/annonc/mdg004.

Abstract

Background: 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.

Patients and methods: The impact of different definitions of primary extranodal NHL on incidence and prognosis is explored using data from a population-based NHL registry.

Results: 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.

Conclusion: 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.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Incidence
  • Lymph Nodes / pathology*
  • Lymphoma, Non-Hodgkin / classification*
  • Lymphoma, Non-Hodgkin / epidemiology*
  • Lymphoma, Non-Hodgkin / pathology
  • Lymphoma, Non-Hodgkin / therapy
  • Male
  • Middle Aged
  • Neoplasm Staging
  • Prognosis
  • Registries
  • Remission Induction
  • Risk Factors
  • Survival Rate
  • Treatment Outcome