Lymphoma in dogs: doxorubicin + cyclophosphamide vs doxorubicin alone — POSSIBLE (the treatment made no difference)

In dogs with treatment-naïve multicentric lymphoma, does adding cyclophosphamide to doxorubicin lengthen progression-free interval vs doxorubicin alone?

Shelf #101 · gate-verified and approved by the developer

POSSIBLE (the treatment made no difference): In the only randomised, placebo-controlled trial found for this question — 32 dogs with stage III–V multicentric lymphoma, all treated with doxorubicin every 3 weeks for five cycles plus a tapering 4-week prednisone course — adding cyclophosphamide did not statistically improve response rate, progression-free interval or survival time over doxorubicin plus placebo (Lori 2010). Outcomes were numerically better in the cyclophosphamide dogs, and the combination was well tolerated with no increase in adverse events, but with only 15 dogs on the combination and 17 on placebo the trial was small, and its abstract reports no numeric progression-free interval or survival figures — so a modest benefit cannot be excluded, only that none was shown. The record establishes randomisation and a placebo control but does not state blinding. Drafted Nov 10, 2026 (VetMed build, topic #101); all figures from abstracts fetched and verified at drafting.

Lori 2010: adding cyclophosphamide to doxorubicin did not statistically improve response, progression-free interval or survival in 32 dogs

Randomized, placebo-controlled study (record's own title wording); indexed as Randomized Controlled Trial

Who: Dogs: 32 dogs with stage III–V multicentric lymphoma, all treated with doxorubicin every 3 weeks for five total cycles and prednisone at a tapering dose for the first 4 weeks; dogs were randomized to receive either cyclophosphamide (n = 15) or placebo (n = 17) concurrently with the doxorubicin.

Result: Response, toxicity, progression-free interval (PFI) and survival time (ST) were evaluated. The combination of doxorubicin and cyclophosphamide was well tolerated, causing no increase in adverse events over doxorubicin alone. Despite a numeric improvement in outcome in cyclophosphamide-treated dogs, the addition of cyclophosphamide did not result in statistically improved response rate, PFI or ST. The record's abstract gives no numeric response-rate, PFI or survival-time values for either group, so none are carded here.

Watch out: Small single trial (32 dogs) — a numeric improvement that did not reach statistical significance in a trial this size is weak evidence either way, and the absence of numeric PFI/ST values in the abstract limits what can be checked. The record's title and abstract establish a randomised, placebo-controlled design and the record is indexed as a Randomized Controlled Trial, but neither the title, the abstract nor the MeSH list (which includes Placebos but no Double-Blind Method) states that the trial was blinded. Both groups also received prednisone, so this is doxorubicin + prednisone with or without cyclophosphamide, not doxorubicin in isolation.

Lori JC, Stein TJ, Thamm DH. Doxorubicin and cyclophosphamide for the treatment of canine lymphoma: a randomized, placebo-controlled study. Vet Comp Oncol. 2010;8(3):188-95. PMID: 20691026. Registry ID: none in the record. MeSH: Animals · Antibiotics, Antineoplastic · Antineoplastic Agents, Alkylating · Antineoplastic Agents, Hormonal · Antineoplastic Combined Chemotherapy Protocols · Cyclophosphamide · Disease-Free Survival · Dog Diseases · Dogs · Doxorubicin · Female · Lymphoma · Male · Neoplasm Staging · Placebos · Prednisone · Prognosis · Schools, Veterinary · Survival Analysis · Treatment Outcome

Synthesis: one small randomised trial — no shown gain from adding cyclophosphamide, and no added toxicity

Synthesis

Who: Synthesis of the card above: Lori 2010 (randomized, placebo-controlled study; 32 dogs with stage III–V multicentric lymphoma on doxorubicin + tapering prednisone, 15 with added cyclophosphamide vs 17 with added placebo).

Result: The trial answers the shelf's question directly and negatively on its own terms: response rate, progression-free interval and survival time were all numerically better but not statistically improved with cyclophosphamide, while adverse events did not increase. That combination — a direct randomised comparison, a coherent null across three outcomes, and a very small sample — is why the stamp is POSSIBLE (the treatment made no difference) rather than stronger or weaker: the design can detect a large effect, but 32 dogs cannot exclude a modest one.

Watch out: The shelf's boundary is the trial's population and backbone: stage III–V multicentric lymphoma treated with a five-cycle doxorubicin + prednisone backbone. It says nothing about multi-agent CHOP-type protocols, which are a different question (topic #102).

Synthesis of Lori JC et al. PMID: 20691026. Registry ID as on the individual card.

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