Lymphomas represent about 4% of the new cases of cancer diagnosed in the U.S. each year. They constitute the fifth most common cancer diagnosis and the fifth leading cause of cancer deaths. In fact, although the incidence of most cancers is decreasing, lymphoma is one of only two tumors that are increasing in frequency. The cause of this increase is unknown.
B-cell lymphomas, a type of non-Hodgkin’s lymphoma (NHL), account for approximately 85% of the approximately 56,000 new cases of NHL diagnosed annually in the U.S. These lymphomas are specifically characterized in subtypes by numerous chemical and genetic attributes. They are generally classified into two subsets used to define outcomes: indolent (slowly growing) and aggressive (rapidly growing). official canadian pharmacy
NHL comprises a heterogeneous collection of lympho-proliferative malignancies. These are most common in people older than 55 years of age.
- According to the World Health Organization (WHO) classification, diffuse large B-cell lymphoma (DLBCL) is the most common subtype of NHL, accounting for approximately 31% of all new patients.
- Follicular lymphoma (FL) is the second most common NHL subtype, accounting for another 22% of cases.
- Mantle-cell lymphoma (MCL), another subtype, represents 6% of cases.
- Small lymphocytic lymphoma with chronic lymphocytic leukemia (SLL/CLL) represents another 6% of NHL cases.
Demographics and Etiology
Over the past 30 years, there has been a steady increase in the incidence of NHL; more cases have been diagnosed in men than in women, at a median age above 50 years. Although the exact causes of B-cell lymphomas are unknown, several environmental factors and genetic abnormalities are believed to play a role.
Aggressive B-cell lymphomas are typically treated with radiotherapy, chemotherapy regimens, biologic agents, or a combination of treatments. The overall five-year survival rate for patients with NHL is approximately 60%, but response rates and survival vary greatly according to the grade and type of B-cell lymphoma being treated.
Recently, there has been great interest in a new molecular technique that has enabled clinicians to distinguish genetically between lymphomas. The Lymphochip is essentially a small piece of glass on which are contained, in a grid-like pattern, thousands of genes expressed by normal B cells. Using this gene chip, researchers can study the genetic expression of a particular malignant lymphoid cell.
Through this technique of gene-expression profiling, it has been discovered that DLBCL consists of two different diseases: germinal-center B-like DLBCL and activated B-like DLBCL.
More than 75% of patients with germinal-center B-like DLBCL were alive five years after treatment, compared with fewer than 25% of patients with the latter type. It is hoped that such information will help physicians understand the molecular basis of differences in treatment outcomes. Armed with this information, physicians may be able to identify patients who are not likely to respond to current treatment so that more targeted or experimental treatments may be offered. viagra soft
The molecular classification of tumors according to gene expression can thus identify previously undetected and clinically significant subtypes of cancer. Measurement of the expression of six genes is sufficient to predict overall survival in DLBCL. The genes that were the strongest predictors were LMO2, BCL6, FN1, CCND2, SCYA3, and BCL2. New therapeutic agents may be directed against one or several of these genes.