Nutritional Consequences of Anti-cancer Therapy

4. Nutritional Consequences of Anti-cancer Therapy

Debilitated cats with advanced alimentary lymphoma represent some of the most challenging cases in medical oncology. The poor nutritional status in these patients is typically a result of a combination of factors resulting in prolonged inadequate nutrition. These signs may be direct effects of gastrointestinal involvement, stage of disease or may also, in part, be due to a deranged metabolic state secondary to cancer cachexia syndrome.

Secondary Effects of Chemotherapeutic Protocols

Regardless of the pathogenesis, in order to reverse these signs, treatment of the underlying malignancy is necessary. This requires the use of chemotherapy. The choice of chemotherapeutic protocol is influenced by cell type or lymphoma grade. Most oncologists use a combination of chemotherapeutic drugs including, prednisone, asparaginase, vincristine, cyclophosphamide, methotrexate, and doxorubicin to treat cats with intermediate to high grade lymphoma (intermediate to large cell type) (Moore et al, 1996; Valerius et al, 1997; Vail et al, 1998; Zwahlen et al, 1998; Krystal et al, 2001; Teske et al, 2002; Richter, 2003; Milner et al, 2005). Many of these drugs are associated with gastrointestinal signs such as nausea, vomiting, anorexia, diarrhea, and fatigue; clinical signs which many of these cats already exhibit. Debilitated patients may be more likely to experience adverse reactions to treatment, require dose reductions, have a decreased response to treatment and have a worse outcome. The induction phase can be particularly difficult and requires careful monitoring of tumor response, addressing toxicity from treatment as needed and constant assessment of the general status of the cat.

A cat with alimentary lymphoma and severe weight loss. (©Alex German).

Variability of Individual Responses

Lymphoma is a chemotherapy-responsive malignancy and some cats with high grade lymphoma may go into remission quickly, tolerate the chemotherapy and improve without specific nutritional intervention. However, others may take longer to respond and/or become increasingly intolerant to chemotherapy and suffer progressive weight loss through the induction phase. Some of these cats may never attain remission and fail early, and others may be taken off chemotherapy prematurely due to unacceptable toxicity and poor quality of life. These cats require intervention.

A prospective study on the incidence of toxicity and overall quality of life in dogs and cats treated with chemotherapy at the University of Pennsylvania confirmed that weight loss, vomiting, and anorexia were more common in cats than dogs (Bachman et al, 2000). Sixty percent of the cats lost weight in the induction phase, this is in sharp contrast to the situation in dogs, where close to 70% gained weight (p = 0.0077). Doxorubicin was the drug most often associated with weight loss and vomiting in both cats and dogs. These results reflect the complexity of the situation. Chemotherapy is necessary to treat the underlying malignancy, yet it may also exacerbate the clinical signs and contribute to further weight loss, vomiting, diarrhea and reduced quality of life. The overall median survival of cats with lymphoma is less than one year; poor nutritional status and low body weight are associated with worse outcome in cats (Baez et al, 2007). It is unknown whether early intervention to reverse the loss of weight and body condition improve outcome in these cats, but these results clearly show that more attention should be paid to ensuring adequate nutritional support, both to improve quality of life as well as to potentially prolong survival.