Page 324 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

302 PART III Therapeutic Modalities for the Cancer Patient

acid, vitamin E, selenium, and vitamin D. In veterinary medi- Implementing a Nutritional Plan for the
cine these nutrients have not been studied in a prospective or Oncology Patient
retrospective fashion. The findings in human meta-analyses
VetBooks.ir examining oral supplementation for single nutrients (e.g., ascor- Nutritional Assessment
bate, selenium, vitamin E) have been inconclusive or negative
with regard to protective antineoplastic effects. 282 β-Carotene, To fully assess the cancer patient, information about body weight,
the precursor to retinol, currently is thought to be ineffective the body condition score, and a dietary history are crucial. The
as an antineoplastic agent, and in some instances has proven dietary history, before and during treatment, should be obtained
to be harmful in certain populations (i.e., smoking popula- to assess kilocaloric intake appropriately. This information allows
tions). 283–285 Currently vitamin D status and supplementa- the practitioner to feed the patient appropriately during hospital-
tion have been an area of intense epidemiologic investigation ization and, more importantly, to recognize hypophagic behav-
because of the relative risks of various neoplastic diseases being iors, allowing for interventions. A typical diet history should
higher for individuals with low serum vitamin D. 286–288 Unlike include the forms of food (wet or dry), amounts fed daily, and
in humans, vitamin D status in dogs and cats directly depends treats, human table foods, and additional supplements provided.
on dietary intake because they cannot convert 7-OH-dehydro- Serial assessment of body weight is important, particularly
cholesterol to pre–vitamin D. One would expect that serum when malnutrition is a consideration. Malnutrition often is asso-
vitamin D concentrations would not fluctuate tremendously ciated with cachexia and/or anorexia. Anorexic behavior can be
in dogs fed commercial dog food. 289 Multiple investigations deduced from the dietary history and can be treated aggressively
suggest that dogs with lymphoma and MCT (but not OSA) with nutritional and/or pharmacologic intervention; however, if
have lower serum vitamin D levels than healthy, breed- and age- cachexia is suspected, then alternative treatments can be sought.
matched dogs, which makes vitamin D status an interesting area The difficulty in clinically differentiating cachexia from anorexia is
of investigation. 290,291 Part of the conundrum in dogs is that the our inability to measure loss of lean versus fat mass. The loss of fat
serum concentrations are about double normal human values, mass is typical during anorexia, whereas equal loss of lean and fat
and it is possible that the supplementation of pet foods ensures mass suggests cachexia. Although this cannot be deciphered effi-
adequate serum concentrations. The lower limit of normal ciently in veterinary practice, overall weight loss guidelines have
ranges from 60 to 100 ug/mL. 291 The lack of uniformity in lab- been offered in the human literature; that is, body weight loss of
oratory testing, such as methods involving high- performance 5% in 1 month or 10% in 3 months without conscientious diet-
liquid chromatography versus mass spectroscopy are examples of ing suggests cancer cachexia. 297 This approach may be difficult in
differences in methodology and applied reference ranges. 292,293 veterinary species because routine loss and gain of weight may be
More interestingly, when dogs with serum concentrations of less seasonal, and the burden of gastrointestinal (GI) parasites poten-
than 100 ug/mL are supplemented with oral cholecalciferol at tially confounds weight loss issues. Two body condition scoring
the safe upper limit established by the National Research Coun- systems have been adopted as a means of nutritional assessment
cil, serum 25-OH-cholecalciferol serum concentrations do not in companion species; however, the 1 to 9 body condition scoring
increase. 294 This suggests that there may be inherent pathways system (see Fig. 16.2) is better validated in the literature. 469, 470
in individuals to eliminate vitamin D from the body which Modest differences in body condition scoring between dogs and
may just represent metabolic differences between dogs. These cats exist because of preferential deposition of body fat along the
findings further corroborate that serum 25-OH-cholecalciferol inguinal and abdominal areas in cats, whereas dogs tend to have
status may be a marker for hepatic and renal cytochrome activ- no preferential deposition. These differences may justify a muscle
ity that makes individual dogs more prone to develop cancer condition scoring system in cats (Table 16.7). 268
based on each individual dog’s inherited metabolism. Whether The final component of nutritional assessment consists of a
this is a direct reflection of dietary intake or a reflection of the routine physical examination, complete blood cell count, and
biochemical disposition in affected dogs with cancer remains to chemistry evaluation. Physical exam findings consistent with
be determined. malnutrition include poor hair coat, chronic GI disturbance,
In humans obesity has been associated with an increased seborrhea, lethargy, and pallor. The first signs of chronic nutrient
risk of many cancers, including breast, prostate, colon, and deficiency are often manifested in areas of rapid cellular anorexia/
pancreatic cancers; leukemias; and lymphomas. 270–272 Studies cachexia syndrome turnover, leading to skin, GI, and hematologic
examining this association in companion animals are limited. signs, and should be considered in cases of prolonged anorexia.
The largest retrospective study in dogs showed no associa- Chronic malnutrition can result in low hemoglobin and red blood
tion between body condition and cancer, 260 whereas other cell counts, in addition to hypoproteinemia and hypoalbumin-
epidemiologic studies suggest obese cats and dogs may have emia. Additionally, with the trend toward nontraditional feeding
a slightly higher rate of neoplastic diseases. 295,296 Two other practices, diets may lack sufficient mineral content, including cal-
investigations revealed a more definitive link between obe- cium, iron, and copper, resulting in bone and hematologic mani-
sity in female dogs and mammary carcinoma. 278–280 The risk festations. Many homemade diets lacking supplementation with
of mammary carcinoma was greater in obese spayed dogs in bone meal can lead to secondary hyperparathyroidism and clini-
one study, whereas obesity was an increased risk independent cal osteopenia. 298,299 Clients using nontraditional diets should be
of spay status in another study. 278,280 Both studies suggested educated through consultation with a veterinary nutritionist.
an increased risk when obesity is present at 1 year of age and In dogs, excess body condition (i.e., obesity) may be more of a
one suggested that obesity at 1 year before diagnosis also was concern than malnutrition or deficiency. Treatment of obesity is
associated with an increased risk. 280 The question of whether not a priority in many cancer patients, considering the metabolic
early-onset obesity, much like early spaying, epigenetically pre- changes that may occur during chemotherapy and the potential
disposes mammary glands to an altered risk of cancer remains for treatment-related changes in eating patterns. In one study
to be addressed. body condition did not change from 6 months before diagnosis to