Primary Extranodal Lymphoma: Revised Incidence, Location, Histological Classification and Survival in Zaragoza (Spain), 1992–2002

Background. Leukaemia and non-Hodgkin’s lymphomas (NHL) are the commonest haematological malignancies (HMs), accounting for about 10% of incident cases and 6% of all cancer deaths in the European Union (EU). There are few studies in order to estimate the differences in incidence and survival of primary extranodal Lymphoma (PEL). In Zaragoza (Spain) there is a population-based Cancer Registry (ZPCR), that includes all non-haematological and haematological (HMs) incident cases, conducted since 1960. The main aims of this study are:

1. To review all cases with PEL diagnosis.

2. To estimate the incidence of PEL in the ZPCR registered cases during the period 1992–2002. 2. To calculate the survival of PEL

Methods. All PEL occurred in patients residing in Zaragoza during the period 1992–2002 were selected from ZPCR. All cases were reviewed in order to confirm the primary location and the morphology classification according to REAL. The population at risk was 9.266.609 person-years. The crude (CIR) and age standardized incidence rate (ASR) were calculated, using the European population as standard. Kaplan-Maier method was applied to calculate median survival time and their 95% confidence intervals, as well as 5-year survival. The end of follow-up was 31 December 2007 and Log-Rank was used to compare survival curves.

Results. Among all 4,340 HMs, a total of 1,757 (40.0%) were NHL (CIR: 19×10⁵ person-year), 252 (14.0%) of them were classified as PEL, yielding an ASR of 2.1×10⁵ person-year (males: 140 cases (53.0%), mean age: 59.2 years, ASR: 2.7×10⁵ person-year and females 112 cases (47.0%), mean age: 66.8 years ASR: 1.6×10⁵ person-year. According to topography the most frequent sites were digestive tract (50.4%), skin (19.8%), gland tissue (10.0%), oral cavity-pharynx (7.9%), lung (2.9%), CNS (2.4%), orbit (2.1%) and others (4.5%). The median survival for PEL was 6.61 years (95%CI: 3.7–9.5) and for nodal Lymphomas 5.01 years (95%CI: 4.1–5.9). The 5-year relative survival was 53.5% and 50.0% respectively. There are not significant differences between both groups. Moreover, non significant differences in survival were observed between males and females. Theses results are similar to those found in the EU.

Conclusions. The occurrence of PEL according to gender and mean age is similar to nodal NHL. No significant differences in survival were observed between nodal and extranodal NHL, probably the survival is more conditioned by the histology than topography.