Cancer Flashcards
Cancer is a group of disease characterized by uncontrolled growth and spread of abnormal cells. It is a genetic disease which can be caused by chronic inflammation and also elicits a chronic inflammatory response.
Cancer compromises the function and the structure of the cell creating uncontrolled proliferation or limited apoptosis, also known as programmed cell death.
Cancer cachexia is a syndrome that is characterized by involuntary wt loss, anorexia, early satiety, muscle wasting, and progressive asthenia (loss of strength, muscular weakness) that is associated with a greater risk of organ dysfunction and death.
- Can
Factors that contribute to hypermetabolism and the cachexia process that leads to unintentional wt loss are: multiple abnormalities in pro,CHO, and fat metabolism.
- In general, pt w/ cancer and wt loss have increased hepatic glu production, increased lipolysis with increased production of glycerol and free fatty acids, and increased whole body PRO turnover compared to healthy volunteers.
Factors contributing to hypermetabolism and cachexia
- Recent research suggest that in some cancer pts, tumor-induced changes in host hormones (neuropeptides, cytokines, and neurotransmitters) was related to hypermetabolism and other altered metabolism. These mediators promote a chronic systemic inflammatory state that results in negative effects on appetite and nutrient metabolism such as anorexia and increased PRO degradation.
- Circulating tumor-derived products such as lipid mobilizing factor and proteolysis-inducing factor, which promote catabolic effects on adipose tissue and skeletal muscle.
- Note: Resting energy expenditure was found to be widely varied in cancer pts but gastric, pancreatic, and biliary cancer pts were found to the most hypermetabolic.
Protein Metabolism in Cancer
- Cancer pts have ↑ PRO turnover to be due to ↑ muscle PRO degradation, and impaired PRO synthesis. Whereas in starvation where PRO catabolism slowly decreases in an attempt to preserve lean, body mass, in cancer this is lost and PRO turnover actually ↑s w/ progression of disease and wt loss
Lipid Metabolism in Cancer
- The depletion of adipose tissues and lipid stores due to ↑ed lipolysis is seen in caner pts w/ wt loss.
- Compared w/ normal subjects and cancer pts w/out wt loss, cancer pts w/ wt loss have an ↑ed turnover of fatty acids and glycerol.
Impaired Caloric Intake, Maldigestion, and Malabsorption
- Changes of Taste and Appetite: Many cancer pt c/o decreased taste and appetite, which is hypothesized to be d/t the proinflammatory cytokines and neuropeptides. In addition, cancer treatments including chemotherapy, radiation, and surgery can lead to an alteration in taste, and these changes can persist for mths after therapy completion.
- Cancer pts who receive chemotherapy and radiation may develop food aversions.
- Depression
- Disturbances of the GI tract: GI malignancies (esophageal, gastric, intestinal, and pancreatic) may cause direct mechanical obstruction. Cancer pts may experienced altered intestinal motility from gastroparesis and intestinal pseudo-obstruction (from the tumor), postoperative ileus from surgery and from medication esp chemotherapeutic agents and narcotics.
Malabsorption
- Cancer treatment therapies (chemotherapeutic agents, radiation and surgery) can lead to malabsorption.
- Fistulae, either due to direct tumor invasion, surgery or radiation, cause a bypass of bowel, leading to malabsorption.
- The most significant malabsorption with fistulae is seen in gastrocolic (betw stomach - colon), enterocolic, enteroenteric and enterocutaneous (small intestine - skin). Managing the nutrition in these pts are difficult, and must focus on replacing ongoing loss of fluid, electrolytes and minerals.
Malabsorption
- Small bowel bacterial overgrowth (SIBO) may also contribute to malabsorption by damaging enterocytes. SIBO is usually due to an anatomic abnormality such as a fistulae, strictures, and surgical resections like ileocecal resections (bacteria migrating from colon to SI), and gastric resections (loss protective barrier from gastric acid).
Malabsorption may be due to a protein -losing enteropathy, which has been associated w/ multiple malignancies including gastric cancer, lymphoma, and melanoma.
