Second Primary Malignancies in CTCL Patients from 1992 to 2011: A SEER-Based, Population-Based Study Evaluating Time from CTCL Diagnosis, Age, Sex, Stage, and CD30+ Subtype

Background: Cutaneous T-cell lymphoma (CTCL) is a diverse group of extranodal non-Hodgkin lymphomas with malignant T lymphocytes localizing in the skin. CTCL can mainly be classified as mycosis fungoides, Sézary syndrome, or primary cutaneous CD30+ lymphoma. Patients with CTCL have an increased risk of developing second primary malignancies. Objective: Our objective was to analyze the overall incidence of second primary malignancies in patients with CTCL by age, sex, stage, and the primary cutaneous CD30+ lymphoproliferative subtype of CTCL, as this group has usually been excluded from previous analyses. Methods: We used the Surveillance, Epidemiology, and End Results (SEER) database to evaluate CTCL cases diagnosed between 1992 and 2011. We calculated the multiple primary standardized incidence ratio, comparing the observed incidence of second primary malignant neoplasms in the CTCL patient population versus the general population. Results: CTCL is associated with an overall increased risk of cancers. This incidence is greatest within the first year of diagnosis. The risk of secondary Hodgkin disease is greatest in patients aged ≥60 years; the risk of secondary non-Hodgkin lymphoma is greatest in patients aged 20–39. Males demonstrated a significantly increased risk of developing Hodgkin lymphoma, while females showed a significantly increased risk of developing bronchopulmonary malignancy. Overall, secondary malignancy incidence was significantly elevated for stage I and IV CTCL. Patients with CD30+ CTCL had a significantly higher incidence of Hodgkin lymphoma, non-Hodgkin lymphoma, and urinary cancers than the general population. Conclusion: Occult secondary malignancies, particularly lymphomas, should be considered in adult CTCL patients, including those with the CD30+ subtype.