Impact of obesity and aging on the tumor immuno-environment

Abstract

Cancer is a disease of the aged with the average age of diagnosis being over the age of 55 years in the U.S.A. Significant physiologic changes occur with aging such as the redistribution of body mass towards increased lipid deposition and loss of lean body mass. There has recently been an increased appreciation on the ability of adipose tissue to affect immunological responses. Although the correlation between adiposity and inflammation has been best studied within the setting of diabetes, current research indicates that adipose tissue and its effects on inflammation has tremendous implications in cancer biology. Development of esophageal, colon, rectal, kidney, pancreatic, endometrial, and breast cancer has been associated with being overweight. The link between cancer, aging, adiposity, and the immune system is becoming an increasingly important area of study, and the observable effects that these three factors may exert on one another may be seen sooner rather than later within our society as the onset of obesity is on the rise, meanwhile those who are obese are being affected at younger ages. The CDC reports that an estimated 36 % of adults in the U.S. are considered obese, while the percentage of adults who are overweight but not obese is estimated at an additional 33 %. By 2030, these figures will rise to about 75 % of the U.S. population being overweight with 42 % of the U.S. population considered obese and 11 % severely obese. Thus, the potential impact of healthy aging, adipose tissue accumulation, and obesity upon affecting the immune response to cancerous cells as well as responses in general to immunotherapy merit a detailed examination and is the focus of this chapter.