Second malignancies in patients with primary central nervous system lymphoma

Background. Primary central nervous system lymphoma (PCNSL) is a rare extranodal lymphoma with distinctive biological behaviors. The evolving treatment of PCNSL has greatly improved the outcome for patients with this disease and has stimulated interest in second malignancies (SMs) in patients diagnosed with PCNSL. Methods. The records of 129 cases of PCNSL at Mayo Clinic, diagnosed between January 1, 1988, and November 26, 2012, were reviewed. Data on clinical characteristics, laboratory parameters, treatments, outcomes, and SMs were collected. The mean follow- up time was 44.8 months (range, 0.5-240 months; median, 28.0 months). Results. Altogether, 28 cases with 30 (23.26%) SMs were identified. Twenty (15.50%) patients had prior or synchronous SM. Ten (7.76%) patients developed a subsequent primary cancer after PCNSL. The most common sites of prior or synchronous SMs were prostate (4/20), skin (4/20), and gastrointestinal (3/20). The most common site of the subsequent SM was skin (4/10). Two cases were identified with both prior SM and subsequent SM. Conclusions. Second malignancies in cases with PCNSL were not uncommon and occurred in nearly a quarter of our cohort. Non-melanoma skin cancers were frequently seen. Therefore, screening for SMs should also be considered in long-term follow-up of patients with PCNSL. In addition, the high incidence of subsequent cancer, synchronous cancer, and frequently seen non-melanoma skin cancers may all indicate an immunosuppressed state in patients with PCNSL.