Chronic lymphocytic leukemia: something old, something new and something borrowed...

Chronic Lymphocytic Leukemia (CLL) is a disease of the elderly: almost 70% of diagnoses are made in patients older than 65 years. This indolent lymphoproliferative disorder, manifested by a clonal expansion of mature but functionally defective lymphocytes, is one of the most common leukemias of adults in Western countries. The incidence rate is roughly 2-6 cases per 100,000 persons per year, and increases with age reaching 12.8 cases per 100,000 at age 65 (the mean age at diagnosis). The disease is more common in men, with an incidence ratio of 1.5-2:1. It also has been found to be more common in the Caucasian population, compared to African American, Hispanic, Native American or Asian populations. There are no clear occupational or environmental risk factors for CLL. The prevalence in Caucasian populations suggests a genetic versus an environmental influence on the etiology. A recent study supports an association between blood transfusions and CLL development in 66% patients evaluated.3 However, among the strongest risk factors for the development of CLL is a family history of CLL or other lymphoid malignancy. Retrospective studies have noted increased incidence in first degree relatives. A term coined “genetic anticipation” has also been used to describe a process in which the median age at diagnosis in an affected family decreases in younger generations.2