Changes in dynamics of excess mortality rates and net survival after diagnosis of follicular lymphoma or diffuse large B-cell lymphoma: comparison between European population-based data (EUROCARE-5).

BACKGROUND

Since 2001, the World Health Organization classification of tumours of haematopoietic and lymphoid tissues and the International Classification of Diseases for Oncology (third edition) have improved data collection for lymphoma subtypes in most European cancer registries and allowed reporting on the major non-Hodgkin lymphoma subtypes. Treatment of non-Hodgkin lymphoma has changed profoundly, benefiting patients with follicular lymphoma or diffuse large B-cell lymphoma. We aimed to compare dynamics of cancer mortality in patients with follicular lymphoma or diffuse large B-cell lymphoma in five large European areas using data for survival from the largest number of collaborative European population-based cancer registries (EUROCARE).

METHODS

We considered follicular lymphoma and diffuse large B-cell lymphoma cases in patients aged older than 15 years diagnosed between Jan 1, 1996, and Dec 31, 2004, and recorded in 43 cancer registries in five areas: Scotland and Wales, and northern, central, eastern, and southern Europe. We excluded cases incidentally diagnosed at autopsy or known from death certificates only. The vital status could be updated on Dec 31, 2008, in all registries but the French ones (Dec 31, 2007). We obtained changes in net survival with the Pohar-Perme estimator and excess mortality rate with a flexible parametric model according to age and year of diagnosis.

FINDINGS

We identified 13,988 follicular lymphoma and 25,320 diffuse large B-cell lymphoma cases. We noted improvements in 5-year net survival for all ages between the 1999-2001 and 2002-04 periods for both cancers (except for follicular lymphoma in Scotland and Wales and diffuse large B-cell lymphoma in eastern Europe). For follicular lymphoma, 5-year net survival in northern Europe was 64% (95% CI 58-71) in 1999-2001 versus 75% (69-80) for 2002-04, for Scotland and Wales, it was 71% (66-76) versus 68% (64-72), for central Europe, it was 64% (61-67) versus 72% (70-75), for southern Europe, it was 67% (63-70) versus 73% (70-76), and for eastern Europe, it was 50% (43-57) versus 61% (54-69). For diffuse large B-cell lymphoma, 5-year net survival in northern Europe was 41% (35-49) versus 58% (54-62), in Scotland and Wales, it was 44% (41-48) versus 52% (49-54), in central Europe, it was 46% (44-47) versus 50% (48-51), in southern Europe, it was 44% (42-47) versus 50% (48-52), and in eastern Europe, it was 47% (41-54) versus 46% (43-50). We noted the largest area disparity during the 2002-04 period between eastern and northern Europe. We noted a significant effect of the year of diagnosis on the excess mortality rate for all ages in all areas, except for diffuse large B-cell lymphoma in eastern Europe. The excess mortality rate was not constant during the follow-up period: we noted a high rate early for both lymphomas, except for follicular lymphoma in northern Europe.

INTERPRETATION

Although survival for follicular lymphoma and diffuse large B-cell lymphoma is improving, the results from this study should foster the search for more and better means of improvement of access to adequate care than that at present, as there remains variation in survival between European regions. Study of the dynamics of the excess mortality rate seems to be a useful clinical indicator to help the practitioner's choice of optimum management of patients.

FUNDING

Compagnia di San Paolo, Fondazione Cariplo Italy, Italian Ministry of Health, European Commission, Registre des Hémopathies Malignes de Côte d'Or, and French Agence Nationale de la Recherche.