Splenic marginal zone lymphoma (SMZL) is an indolent neoplasm, mostly occurring in the elderly, with a median survival time exceeding 10 years. The incidence of secondary cancer and late complications related to therapy have not been investigated. To assess the frequency of additional neoplasms in a series of consecutive SMZL patients and to estimate the corresponding risk of second cancers compared with that of the general population. we investigated the incidence of additional cancers in 129 patients diagnosed with SMZL in three italian hematological centers.

With a median follow-up time of 33.2 months, twelve additional invasive cancers were recorded (9.3%). The 3 and 5-year cumulative incidence rates of second malignancy were 5.7% and 19.4%, respectively. Five more patients (3.8%) had a diagnosis of malignant epithelial tumor prior to that of SMZL.

The incidence of second malignancies was slightly, but significantly, higher than the expected incidence rate. The Observed-to-Expected ratio (O/E) was 12/5.92=2.03, 95% confidence interval (CI) 1.05 to 3.56; p <0.05. Of the twelve second malignancies observed, four were urologic neoplasms ( O/E=4/1,08=3.70 (95% CI:1.01 to 9.48; p <0.05), four were lung cancers (O/E=4/0.44365=9.16; 95% CI: 1.41 to 13.25; p <0.05) and the other four diagnosis were of hepatic carcinoma (1), endometrial cancer (1), breast cancer (1), and colo-rectal cancer (1). Our findings evidence an increased frequency of additional neoplasms in patients with SMZL and suggest that this figure is significantly different than that expected in the general population. The incidence of cases with urinary tract and lung malignancies in our series is higher than expected. Although confirmatory data are needed, in our opinion SMZL patients are at risk of secondary maligancies and should be carefully investigated at diagnosis and monitored during the follow-up.

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