Purpose: Chronic lymphocytic leukemia (CLL) is associated with an increased risk of developing second cancers. However, it is unknown whether CLL alters the disease course of these cancers once they occur.
Patients and methods: All patients with cancers of the breast (n = 579,164), colorectum (n = 412,366), prostate (n = 631,616), lung (n = 489,053), kidney (n = 95,795), pancreas (n = 82,116), and ovary (n = 61,937) reported to the SEER program from 1990 to 2007 were identified. Overall survival (OS; death resulting from any cause) and cancer-specific survival were examined, comparing patients with and without pre-existing CLL. Cancer-specific survival was evaluated for each tumor type in a site-specific manner (eg, death resulting from breast cancer in a patient with breast cancer).
Results: Patients with cancers of the breast (hazard ratio [HR], 1.70; P < .001), colorectum (HR, 1.65; P < .001), kidney (HR, 1.54; P < .001), prostate (HR, 1.92; P < .001), or lung (HR, 1.19; P < .001) had inferior OS if they had a pre-existing diagnosis of CLL after adjusting for age, sex, race, and disease stage. These results for OS remained significant for patients with cancers of the breast, colorectum, and prostate after excluding or censoring CLL-related deaths. Cancer-specific survival was also inferior for patients with cancers of the breast (HR, 1.41; P = .005) and colorectum (HR, 1.46; P < .001) who had pre-existing CLL after adjusting for age, sex, race, and disease stage.
Conclusion: Inferior OS and cancer-specific survival was observed for several common cancers in patients with pre-existing CLL. Additional studies are needed to determine the optimal management of these malignancies in patients with CLL and whether more aggressive screening or alternative approaches to adjuvant therapy are needed.