Page 1337 - Small Animal Internal Medicine, 6th Edition

CHAPTER 79 Lymphoma 1309

2 to 4 months of diagnosis; however, prolonged remissions them also underwent either radiation therapy or surgical
(i.e., 6-12 months) are possible. resection (Desmas et al., 2017). In cats with gastric lym-
VetBooks.ir Ocular lymphoma phoma, prolonged survival may be related to the fact that
Ocular lymphoma can be treated using a variety of
Helicobacter spp. may play a role in the development of
modalities. However, the eye behaves similarly to the blood-
gastric lymphoma should be treated with combination che-
brain barrier in that adequate intraocular concentrations of gastric lymphoma, as H. pylori does in people; all cats with
chemotherapeutic agents are usually difficult to attain. If the motherapy and antibiotics proven effective in cats with Heli-
clinician and owner want to try to preserve the animal’s eye, cobacter infection.
there are several alternatives to enucleation. As in animals In cats with epitheliotropic intestinal lymphoma, a
with CNS lymphoma, the administration of cytosine arabi- common, small lymphocytic form of the disease in older
noside as a slow IV drip usually results in remission of the individuals, a more conservative approach is recommended,
tumor (see Fig. 79.11). Lomustine is also effective in dogs which has been associated with excellent results. A combina-
2
and cats with intraocular lymphoma. tion of chlorambucil (20 mg/m PO q2 weeks) plus pred-
Cutaneous lymphoma nisolone (1-2 mg/kg PO q24-48h) or dexamethasone (4 mg/
Cutaneous lymphoma is the one of the most common cat PO q1-2 weeks) is administered; if clinical signs do not
extranodal form of lymphoma in dogs seen in most clinics improve within 3 or 4 weeks, vincristine can be added
2
in the United States. In dogs with cutaneous involvement (0.5 mg/m IV q1-2 weeks). Most cats treated with this pro-
secondary to multicentric lymphoma, the authors use a stan- tocol have marked improvement of the clinical signs and
dard chemotherapy protocol (i.e., COP- or CHOP-based typically gain weight; survival times of 1 to 2 years are
protocols). In dogs with epitheliotropic T-cell lymphomas, common with treatment. Interestingly, some of the cats
we use lomustine (CCNU)-containing protocols. Two studies exhibit no appreciable decrease in mesenteric lymph node
have evaluated the use of lomustine for epitheliotropic cuta- size, despite the remarkable clinical improvement. For these
neous T-cell lymphoma, reporting an overall response rate cats, the author uses the approach of “treating the patient,
of approximately 80%, with 20% to 30% attaining CR and not the disease” (i.e., as long as the patient feels well and is
50% to 60% attaining PR. The overall median duration of free of clinical signs, the current treatment is continued).
response in these studies was approximately 90 days, with Recently, this disease entity has also been documented in
most dogs experiencing progressive disease resulting in dogs by one of the authors (KC), and similar to cats, treat-
death. More recently, rabacfosadine has also been used for ment with a combination of chlorambucil and prednisone
epitheliotropic cutaneous lymphoma, which resulted in a may results in long-term survivals (Couto et al., 2018).
response rate of 45%, and a progression free-survival of 37.5
days (Morges et al., 2014). This is an alternative treatment “Low-Budget” Lymphoma Protocols
option if lomustine has been unsuccessful, or if there are Quite frequently, the clinician is evaluating a dog or cat with
contraindications for its use. As discussed earlier, radiother- lymphoma that should benefit from chemotherapy, but
apy is effective in localized cutaneous/mucocutaneous T-cell because of finances or other issues (e.g., time commitment),
lymphomas. Fig. 79.4 depicts a cat with cutaneous lym- the owners are not interested in the standard multiagent
phoma before and after chemotherapy. chemotherapy approach. The authors have used one of the
Alimentary lymphoma following quite successfully: prednisone alone, prednisone
Both authors use standard chemotherapy protocols (i.e., and chlorambucil, chlorambucil alone, lomustine alone, or
COP or COAP, CHOP-based protocols) in dogs and cats prednisone and lomustine. Although the duration of remis-
with solitary mural or nodal (e.g., mesenteric or ileoceco- sion is shorter than when using COP- or CHOP-based pro-
colic lymph node) involvement of large-cell lymphoma. Even tocols, most of these patients (and their owners) can enjoy
though surgery is not necessarily indicated for these dogs prolonged (i.e., months), good-quality survival times. These
and cats, a fair number are referred after exploratory surgery protocols are listed in Box 79.1.
and an incisional or excisional biopsy has been performed.
In general, the response in these animals is good; however,
it can be short-lived. Dogs and cats with diffuse large-cell Suggested Readings
intestinal lymphoma usually respond poorly to chemother- Alvarez FJ, et al. Dexamethasone, melphalan, actinomycin D, cyto-
apy. Responses to doxorubicin-containing protocols (i.e., sine arabinoside (DMAC) protocol for dogs with relapsed lym-
CHOP) appear to be better than those to COP, although phoma. J Vet Intern Med. 2006;20:1178.
survival times are overall short (4-6 months). Dogs with Berlato D, et al. Radiotherapy in the management of localized
mucocutaneous oral lymphoma in dogs: 14 cases. Vet Comp
colorectal lymphoma and cats with gastric lymphoma tend Oncol. 2012;10:16.
to respond extremely well to COP- or CHOP-based chemo- Bridgeford EC, et al. Gastric Helicobacter species as a cause of feline
therapy, with documented remission times in excess of 3 gastric lymphoma: a viable hypothesis. Vet Immunol Immuno-
years in these subsets of patients. Recently, a study of 31 dogs pathol. 2008;123:106.
with colorectal lymphoma reported a progression free- Burton JH, et al. Evaluation of a 15-week CHOP protocol for the
survival of 1318 days and a disease-related MST of 1845 treatment of canine multicentric lymphoma. Vet Comp Oncol.
days. These dogs underwent chemotherapy, and a portion of epub ahead of print May 2012.