Effect of Gene Polymorphisms on the Pathogenesis of Cancer Cachexia

Overview

Cachexia not only directly increases the morbidity and mortality, it also aggravates the side effects of chemotherapy and reduces the overall quality of life that is often considered the major and direct cause of morbidity of a large proportion (\>40%) of cancer patients. Individuals with upper gastrointestinal tumors have the highest rate of developing cachexia associated complications. Chemical and physical signals render an environment conducive for disuse and untenable for proper muscle function leading to wasting. Till now, several functional single-nucleotide polymorphisms (SNPs) within TNF-α gene have been identified and described as cancer related genetic alterations.

Cachexia is a devastating syndrome that is observed in the majority of end stage cancer patients. Primary symptoms of cancer cachexia comprise of progressive loss in weight and exhaustion of host skeletal muscle tissue as well as adipose tissue reserves. Cancer cachexia is defined as a multifactorial syndrome, characterized by anorexia as well as diminished body weight, loss of skeletal muscle, and atrophy of adipose tissue (Fearon et al., 2011). Specifically, weight loss of more than 5% over 6 months span in previously healthy individuals or more than 2% in subjects with depletion of current body weight (BMI less than 20 kg/m2) or in individuals with reduced appendicular muscle index (males less than 7.26 kg/m2 and females less than 5.45 kg/m2) constitute the diagnosis of cancer cachexia. Among potential mechanisms involved in the development of cachexia, the primary initial process is probably the systemic inflammatory response followed by increased production of pro-inflammatory cytokines, such as TNF-α. Multiple biological activities of TNF-α were found in numerous physiological states, including the regulation of cell differentiation, proliferation, apoptosis and metabolism .

Conditions