Time trends and survival of marginal zone lymphoma over 25 years in Girona, Spain (1994-2018)

Objective: To analyze the incidence, incidence trends, and survival of marginal zone lymphomas (MZLs) in Girona and to describe these indicators based on the location in the case of extranodal MZLs.

Methods: Population-based study of MZL collected in the Girona Cancer Registry, 1994-2018. Sociodemographic data, tumor location, and stage were obtained from clinical records. Crude (CR) and age-adjusted (ASR_E ) incidence rates expressed per 100,000 person-years (p-y) were calculated. Joinpoint regression models were used for the trend analysis according to the MZL group. Five-year observed and net survival were analyzed.

Results: A total of 472 MZLs were included, 44 (9.3%) were nodal, 288 (61.0%) extranodal, 122 (25.9%) splenic, and the rest (n = 18) MZL, NOS. The CR for the MZL was 2.89 × 100,000 p-y (95% CI: 2.63-3.15), the ASR_E was 3.26 × 100,000 p-y (95% CI: 2.97-3.57), and the annual percentage change (APC) was 1.6 (95% CI: 0.5-2.7). The ASR_E for nodal MZL was 0.30 × 100,000 p-y (95% CI: 0.22-0.41) and showed an APC of 2.9% (95% CI: -16.4-26.6). For extranodal MZL, the ASR_E was 1.98 × 100,000 p-y (95% CI: 1.76-2.23) and the APC was -0.4 (95% CI: -2.0-1.2). The most frequent locations of this type of MZL were the gastric (35.4%), skin (13.2%), and respiratory system (11.8%). The ASR_E of the splenic MZL was 0.85 (95% CI: 0.71-1.02) with an APC of 12.8 (95% CI: 2.5-24.0). The 5-year net survival of MZL was 82.1% (95% CI: 76.3-86.5).

Conclusions: This study reveals differences in the incidence and trend of the incidence of MZL according to the subgroup, showing a significant increase in the overall MZL mainly due to splenic MZL type.