INCIDENCE, CLINICOPATHOLOGICAL FEATURES AND OUTCOME OF PRIMARY CENTRAL-NERVOUS-SYSTEM LYMPHOMAS - POPULATION-BASED DATA FROM A DANISH LYMPHOMA REGISTRY

Background: Primary Central Nervous System lymphomas (PCNSL), a rare n eoplasm accounting for only a small fraction of malignant brain tumors and extranodal non-Hodgkin's lymphomas (NHL), seems to occur with inc reasing frequency in immunologically-normal as well as immunocompromis ed individuals. In an attempt to characterize the clinicopathological features, incidence rate and outcome of PCNSL, we here report our expe rience in a large unselected group of patients from a well-defined reg ion. Patients and methods: In a Danish population-based NHL registry ( LYFO) representing a population of 2.7 million, all new cases of NHL w ere registered during the 10-year period from lst January 1983 to 31st December 1992. The number of malignant brain tumors reported to the D anish Cancer Registry from the region covered by LYFO, during the 7-ye ar period from lst January 1983 to 31st December 1989, is compared to the number of PCNSL. Results: During the 10-year period 2687 new cases of NHL were registered. Of these, 1004 (37%) were extranodal and 42 w ere non-AIDS-related PCNSL, accounting for 4.2% of extranodal NHL and 1.6% of all NHL, respectively. The incidence rate for PCNSL during the ten-year period (age range: 21-85 yrs, median: 62 yrs, M/F ratio: 0.9 ) was 15.6 cases per million population. Eighteen and 24 cases were di agnosed during the first and the second 5-year period, respectively (p > 0.05). During the 7-year period 1866 primary malignant brain tumors were registered in the region covered by the LYFO study group. In the same period 30 cases of PCNSL were detected. Thus, PCNSL accounted fo r 1.6% of all primary malignant brain tumors diagnosed in Western Denm ark. Histologically, 83% were high-grade. Using the Kiel classificatio n centroblastic diffuse (62%) and immunoblastic lymphoma (12%) were th e most common subtypes. Thirty-seven patients had B-cell lymphoma; no T-cell lymphomas were detected. Forty-one cases were diagnosed pre mor tem. Treatment included surgical resection (23 patients), whole brain irradiation (WBRT) (37 patients) and chemotherapy (22 patients). Media n survival for those receiving either WBRT or WBRT and chemotherapy wa s 7.5 months and 12 months, respectively (p > 0.05). Survival was 43.9 %, 31.7% and 7.3% at 1, 2 and 5 years.