Page 1333 - Small Animal Internal Medicine, 6th Edition

CHAPTER 79 Lymphoma 1305

Lomustine (CCNU) is typically used in dogs with epith- During this phase the patient is examined every 6 to 8
eliotropic T-cell lymphoma (see Box 79.1) and, as discussed weeks, at which time a complete physical examination and a
VetBooks.ir earlier, for one of the authors (GC), as part of the mainte- CBC are performed. As with the induction protocols, owners
are instructed to monitor their pet’s activity, appetite, behav-
nance or reinduction protocol in dogs with other large-cell
T-cell lymphomas.
In dogs and cats with multicentric lymphoma (or any ior, and lymph node size. As discussed previously, is it rec-
ommended that the owners of pets with multicentric
other anatomic form) coexisting with neurologic or ocular lymphoma are instructed to closely monitor the size of the
signs, one author (GC) usually uses the COAP protocol but lymph nodes; when the nodes start enlarging (i.e., relapse),
administers the cytosine arabinoside as a continuous IV a fourth drug can be added to the LMP protocol (usually
2
2
infusion (200-400 mg/m as an IV infusion over 24 hours vincristine, at a dosage of 0.5-0.75 mg/m IV q1-2 weeks).
for 1-4 days) to attain high concentrations of this drug in This usually suffices to reinduce remission and maintain it
the CNS. This protocol tends to cause marked myelosuppres- for several weeks or months.
sion in cats, so cytosine arabinoside is typically administered Most patients treated with this protocol remain in remis-
2
as a 12- to 24-hour infusion (200 mg/m ) in this species. sion for approximately 3 to 6 months. If a relapse occurs,
More information on the treatment of dogs and cats with reinduction of remission (as discussed next) is instituted.
suspected or confirmed CNS lymphoma is given later in After remission is reinduced, animals can be treated with a
this chapter. modified maintenance protocol, as described in previous
Maintenance paragraphs.
The protocol recommended by one of the authors (GC)
for the maintenance phase of treatment is LMP (“lump”), CHOP-Based Protocols
which consists of chlorambucil, methotrexate, and predni- When using CHOP-based protocols (favored by one of the
sone (see Box 79.1). These drugs also act by three different authors—KC), a 4 to 6 month protocol without long-term
mechanisms of action and have differing toxicities. The maintenance is used. Typically, weekly to twice monthly che-
advantages of this protocol include its reduced cost com- motherapy with a combination of cyclophosphamide, doxo-
pared with the cost of the induction phase; its ease of admin- rubicin, vincristine, and prednisone is used for a total of 4
istration (all the drugs are administered orally by the owners); cycles; the main difference between the UW-19 and UW-25
its minimal toxicity; and the fact that intensive monitoring protocol are a longer interval between treatments during the
by a veterinarian is not necessary. second half of the protocol. As stated earlier, these drugs
The toxicities associated with LMP maintenance chemo- have differing mechanisms of action and do not have super-
therapy are minimal. Of the three drugs in this protocol, imposed toxicities, again fulfilling the criteria for traditional
methotrexate is the only one associated with moderate to multiagent chemotherapy described in Chapter 76. Doxoru-
severe toxicity. Approximately 25% of dogs and cats receiv- bicin can be associated with a slightly higher risk of gastro-
ing methotrexate develop gastrointestinal tract signs con- intestinal adverse effects than the other drugs in this protocol,
sisting of anorexia, vomiting, or diarrhea. Anorexia and and the author (KC) generally uses Cerenia after each dose
vomiting are more common than diarrhea, and usually of doxorubicin to help limit this toxicity. Fasting before
occur after the patient has been receiving the drug for more doxorubicin administration has also been associated with a
than 2 weeks. In these cases, treatment with an antiemetic lower frequency of delayed vomiting, so this should also be
such as metoclopramide on the days the animal receives considered. During treatment, similarly to the previously
the methotrexate, at a dosage of 0.1 to 0.3 mg/kg PO q8h, described recommendations, owners are instructed to
alleviates or eliminates the upper gastrointestinal tract monitor their pet’s appetite, activity level, lymph node size
signs. Use of maropitant (Cerenia, Pfizer Animal Health, (if peripheral lymphadenopathy was present initially), and
Kalamazoo, Mich) at a dosage of 2 mg/kg PO q24h for take their pet’s rectal temperature if they are unwell. Addi-
dogs, and 1 mg/kg PO q24h for cats can also be consid- tionally, the patient is examined every 1 to 2 weeks, at which
ered to prevent chemotherapy-associated nausea and vomit- time a complete physical examination and CBC are per-
ing. Gastroprotectants such as famotidine (0.5-1 mg/kg PO formed. After completion of the 4 to 6 month protocol,
q12h) may also be effective in preventing or minimizing patients are examined every 4 to 6 weeks, to assess for relapse
this adverse effect. In cases of methotrexate-associated diar- of their lymphoma, and if any overt abnormalities were
rhea, treatment with a bismuth subsalicylate–containing present on CBC or chemistry panel before diagnosis (i.e.,
product (Pepto-Bismol) may also alleviate or eliminate circulating neoplastic cells, liver enzyme elevation, etc.), this
the signs; however, it may be necessary to discontinue the bloodwork is repeated. If no previous abnormalities were
drug. Hematologic toxicity associated with LMP therapy is present, then full bloodwork is rechecked every 3 months to
minimal to nonexistent. In a small proportion of cats (i.e., assess for development of any concerning findings related to
<5%) receiving chlorambucil for weeks to months, serum relapse of lymphoma.
biochemical abnormalities consistent with cholestasis that These conventional CHOP-based chemotherapy proto-
resolve with discontinuation of the drug may develop. Tonic cols have been associated with remission rates of approxi-
or tonic-clonic convulsions can also rarely occur in cats mately 85% to 95% in dogs with high-grade lymphoma, and
receiving chlorambucil. 60% to 70% in cats with high-grade lymphoma. The typical