Second Cancer Incidence Among Chronic Lymphocytic Leukemia (CLL) Patients: A French Population-Based Study

Introduction. The risk of developing a second primary cancer (SPC) is increased in patients with CLL. The mechanisms explaining this association could be related to lifestyle, environment, host factors or interactions or other influences. We conducted an epidemiological study based on 10 French registries and evaluated the risk of developing SPC in patients with CLL.

Methods. Data from French population-based registries were used to establish a cohort of all patients diagnosed with a first cancer between 1989 and 2004 and followed-up until December 31, 2007. The person-year approach was used to estimate Standardized Incidence Ratios (SIRs) and Excess Absolute Risks (EARs) of metachronous SPC. Multivariate Poisson regression modules were then used to model SIRs and EARs separately by gender, adjusting for age, year of diagnosis, follow-up and first cancer site. All patients with CLL did not have HIV/AIDS-related disease.

Results. Among 288,967 patients, 21,226 patients (7.5%) developed SPC. Among 4,148 CLL patients (Male: 2,336, Female: 1,812, median age: 70 years), 479 patients (11.5%) developed SPC after a median time of 54 months (2-199). EARs of SPC are different between male and female. In male, localizations of SPC are lung, bronchus and trachea, colorectum, colon, stomach and Hodgkin's disease. Their respective EARs are shown in table 1 and no excess absolute risk was observed for 24 other localizations. In female, localizations of SPC are rectum, stomach and melanoma of skin. Their respective EARs are shown in table 2 and no excess absolute risk was observed for 21 other localizations.

Conclusion. The risk for developing SPC after CLL is increased for male and female, especially solid cancers. Except Hodgkin's disease for male patients, there is no increase for other malignant hematological diseases, including acute leukemia and myelodysplastic syndrome. CLL survivors face a high risk of new malignancies and the excess risk of SPC increases with follow-up. As the SPC risk is closely tied to patient's characteristics, a personalized surveillance is required to allow optimal SPC prevention and early detection strategies.