The pancreas is part of a highly effective and coordinated gastrointestinal (GI) tract that is designed to break down food into tiny pieces that can be absorbed across the wall of the small bowel into the blood stream. From there, nutrients are carried through the body and used for energy or to build new tissues.
When the pancreas is affected by cancer, it affects the absorption and use of many of the nutrients needed by the body:
The tail of the pancreas produces insulin, a messenger that travels through the bloodstream to signal cells to clear sugar from the blood. Type 1 diabetes, which requires insulin therapy to control blood sugars, can develop in some patients and may actually be diagnosed prior to the finding of the pancreatic cancer itself.
Most pancreatic cancers are found in the head and body of the pancreas and affects the secretion of enzymes (lipase, amylase and protease) and bicarbonate into the small intestine. The bicarbonate helps neutralize stomach acid and improve the function of the enzymes which break down fats, carbohydrates and proteins in food.
The majority of patients with pancreatic cancer will have pancreatic enzyme insufficiency (PEI), and it is estimated that 50% of patients develop insufficiency after Whipple surgery. With PEI, food is not completely broken down during its passage through the GI tract. Part of it is delivered to the colon, which typically receives only the fiber that humans cannot digest, and eventually becomes part of the stool that is excreted. Symptoms of malabsorption include:
- Gas and bloating, when bacteria in the colon (probiotics) ferment the extra food being delivered to them.
- Foul smelling stools, from unabsorbed fat.
- Stools that float on the surface of the water in the stool basin. These stools are often yellow in color and frothy, and are often associated with a greasy film on the surface.
- Frequent, loose stools (diarrhea) may occur, but since many patients are on narcotic pain medications that slow the contractions of the GI tract. This can counter the diarrhea that would otherwise occur.
- Weight loss, as the result of an inability to absorb part of the food that is eaten.
Effective treatment for malabsorption includes:
- Addition of supplemental pancreatic enzymes. It is important that patients understand the appropriate timing of enzymes. They must be taken with every meal or snack that contains any fat content, traveling with the food as it moves along the GI tract. Dosing should begin with 10,000 to 40,000 units of lipase per meal or snack, depending on the degree of symptoms. These initial doses should be adjusted upwards if symptoms improve with consistent use of enzyme therapy, but do not resolve. With experience, patients learn to adjust the dose depending on the fat content of the meal, frequently finding they need less at breakfast than at later meals. Enzyme dosing can be increased to a maximum dose of 10,000 units of lipase per kilogram of body weight per day, but this level of support is rarely needed.
- Anti-diarrheals (OTC Immodium or prescribed Lomotil) can slow contractions along the GI tract, where needed. Tincture of opium and Sandostatin injections are sometimes used to manage continued, uncontrolled diarrhea. Enzymes must have enough time to get in contact with the food as it travels through the GI tract.
- A basic/alkaline environment is needed for both bile and enzymes to break down and absorb fat effectively. Where symptoms continue, the addition of an H2-receptor antagonist (i.e. Pepcid, Zantac) or a proton-pump inhibitor (i.e. Prilosec, Nexium) can improve the effectiveness of enzyme therapy.
- Restriction of fat in the diet is recommended only if other measures are unsuccessful, and is typically limited to 75 g per day. This is a last resort, since fat is an important source of calories needed to avoid weight loss.
- IF symptoms are not adequately controlled despite pancreatic enzyme therapy, water-soluble versions of fat soluble vitamins (VITAMAX AND AquaDEKs) may be needed. B12 levels should also be monitored and supplemented if needed.