Scientists have also since discovered that CLL is not a uniform disease but rather a disease that follows two distinct clinical courses in patients. Some patients require no treatment and have a lifespan of more than 20 years after diagnosis. Since the disease most often strikes older adults, the patients whose disease follows this course usually die with the disease, not because of it. CLL may also follow a more aggressive course. In these cases, patients do require chemotherapy and have a lifespan of only about six to eight years after diagnosis despite treatment.
Scientists, including Drs. Chiorazzi, Rai and others at North Shore-LIJ, as well as other research groups in Bethesda, MD, San Diego, CA, and Barcelona, Spain, have identified genetic and protein markers that can predict whether a CLL patient will follow the benign or aggressive course. Some markers are not yet available for clinical use, however according to the review, measurement of one protein marker called ZAP-70 is becoming more widely available. The authors note that ZAP-70 may actually be the most reliable indicator of prognosis known to date.
After discussing B lymphocytes -- the type of white blood cell that gives rise to CLL, the biology of leukemic lymphocytes and the clinical course of CLL as it relates to the biology, the authors then offer a unifying hypothesis for the development, growth and evolution of the disease, and complete the review with a discussion of the clinical implications for practicing physicians.