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.