Exploring the Relation Between Coexisting Chronic Lymphocytic Leukemia and Lung Cancer: Two Case Reports.

Chronic lymphocytic leukemia (CLL) is a low-grade lymphoproliferative disorder characterized by clonal proliferation of lymphocytes. The disease is indolent but might be complicated with life-threatening cytopenias, high-grade transformation, or second primary malignancies (SPMs). The incidence of SPMs is higher in CLL compared to the normal population; however, the genetic association and predisposing factors linking CLL to SPMs remain unclear. Synchronous or metasynchronous CLL and lung cancer are relatively uncommon, and the relationship is rarely explored in the literature. We report two cases of a 77-year-old male and a 52-year-old female with a history of heavy smoking, both presenting with respiratory symptoms. Imaging revealed lung masses, hilar adenopathy, pleural effusions, and visceral metastasis. The first case's pleural fluid cytology was positive for both CLL and adenocarcinoma, while the second patient was diagnosed with a biopsy from the right supraclavicular mass revealing carcinoma. In both patients, a flow cytometry of the peripheral smear confirmed the diagnosis of CLL. Both patients had a similar outcome of death due to complicated intracerebral metastatic disease with intracranial hemorrhage and vasogenic edema within 1-2 months of diagnosis. Although incompletely understood, CLL and lung cancer share some predisposing social and biological factors, of which smoking is the most evident. It is also thought that the immunocompromised state of CLL patients is a risk factor for SPMs, given qualitative and quantitative defects in almost all immune cell lines. The cytogenetic association has been suggested but has yet to be comprehensively explored. The proposed tumor factors include HER-2/neu overexpression in lung cancer cells and Trisomy 12 in B-cell clones, which neither of our patients had. Despite suggested links, the relationship between CLL and lung cancer needs further exploration which might offer a future benefit for anticipation and earlier detection of lung cancer in CLL patients.