VetMedOsteosarcoma in dogs: adjuvant platinum chemotherapy after amputation vs amputation alone — POSSIBLE
In dogs with appendicular osteosarcoma, does adjuvant platinum chemotherapy after amputation prolong survival vs amputation alone?
Shelf #110 · gate-verified and approved by the developer
POSSIBLE: The direct comparison favours chemotherapy by a wide margin, but no randomised trial of platinum chemotherapy against amputation alone is in these records — the draft anchor called Straw 1991 a 'randomised cisplatin study', and its record does not support that: the record's publication types are Journal Article only, and its abstract describes three treatment groups (17, 19 and 35 dogs) with no statement of random allocation. In that non-randomised Colorado State comparison, median survival was 262 days for amputation plus two postoperative cisplatin doses and 282 days for cisplatin given before and immediately after amputation, vs 119 days for amputation alone, with both cisplatin groups' survival significantly longer than amputation alone (the abstract gives no P value for that comparison). A second platinum agent points the same way against a weaker comparator: in Bergman 1996, a prospective single-arm carboplatin trial (48 dogs, up to 4 doses), median survival was 321 days with 35.4% of dogs alive at 1 year, reported as statistically longer than previously reported amputation-alone results (P < .001) — a historical comparison, not a concurrent control. A randomised trial does exist for what platinum regimen to give, not for whether to give it: Skorupski 2016 randomised 50 amputated dogs to six doses of carboplatin vs alternating carboplatin/doxorubicin and found a longer disease-free interval with carboplatin alone (425 vs 135 days, P = 0.04). The effect size (median survival roughly doubled or more in every comparison) and its consistency across two platinum agents are why this shelf is POSSIBLE rather than MAYBE (weak evidence), but selection bias in non-randomised groups — fitter dogs are likelier to be offered chemotherapy — can inflate exactly this kind of comparison, which caps it there. Tier C: this is a survival claim, for John's personal ruling. Drafted Nov 10, 2026 (VetMed build, topic #110); all figures from abstracts fetched and verified at drafting.
Straw 1991: median survival 262 and 282 days with cisplatin (after, or before + after, amputation) vs 119 days with amputation alone — significantly longer, in a NON-randomised comparison
Comparative study with concurrent amputation-alone group (record's own publication types: Journal Article; randomisation not stated)
Who: Dogs: 71 dogs with histologically confirmed appendicular osteosarcoma in a referral (Colorado State programme) setting: 17 dogs treated with amputation and two postoperative IV cisplatin doses 21 days apart (group 1), 19 dogs treated with IV cisplatin 21 days before amputation and a second dose immediately after amputation (group 2), and 35 dogs treated by amputation of the affected limb with no chemotherapy (group 3).
Result: The median disease-free interval was 226 days for group 1 and 177 days for group 2, not significantly different between them. Median survival time was 262 days for group 1, 282 days for group 2 and 119 days for group 3. Groups 1 and 2 had survival times significantly longer than group 3 (no P value is given in the record for that comparison). The authors conclude that two IV courses of cisplatin given before or after amputation appear to improve the survival of dogs with osteosarcoma.
Watch out: ANCHOR CORRECTION: the draft described this as a randomised study — the record does not establish randomisation (no random-allocation wording in the abstract; publication types list Journal Article only, no Randomized Controlled Trial). How dogs came to be in the chemotherapy groups vs the amputation-alone group is not stated, so selection bias is a live alternative explanation for part of the survival gap. The chemotherapy tested was only two cisplatin doses — fewer than modern multi-dose platinum protocols — and the record gives no P value for the survival comparison against group 3.
Straw RC, Withrow SJ, Richter SL, Powers BE, Klein MK, Postorino NC, LaRue SM, Ogilvie GK, Vail DM, Morrison WB. Amputation and cisplatin for treatment of canine osteosarcoma. J Vet Intern Med. 1991;5(4):205-10. PMID: 1941754. Registry ID: none in the record. MeSH: Amputation, Surgical/veterinary · Animals · Cisplatin/therapeutic use · Combined Modality Therapy · Dog Diseases/drug therapy,mortality,surgery · Dogs · Extremities/surgery · Female · Male · Osteosarcoma/drug therapy,mortality,surgery,veterinary · Treatment Outcome
Bergman 1996: amputation + carboplatin — median survival 321 days, 35.4% alive at 1 year, reported longer than previously published amputation-alone results (P < .001, historical comparison)
Prospective clinical trial, single-arm (record's own publication types include Clinical Trial and Multicenter Study; no concurrent control group)
Who: Dogs: 48 dogs with histologically confirmed appendicular osteosarcoma in a prospective multicentre clinical trial, treated with amputation and up to 4 doses of carboplatin (300 mg/m2) given every 21 days.
Result: The median disease-free interval was 257 days, with 31.2% of dogs disease-free at 1 year. Median survival time was 321 days, with 35.4% of dogs alive at 1 year. Dogs with proximal humeral osteosarcoma had shorter disease-free interval (P = .016) and survival (P = .037) than dogs at other locations; dogs with lower body weights (<40 kg) had longer disease-free interval (P = .0056) and survival (P = .007) than larger dogs. Survival times for dogs receiving carboplatin were statistically longer than those previously reported for amputation alone (P < .001). Carboplatin was well tolerated at 300 mg/m2 every 21 days; neutropenia was the dose-limiting toxicity.
Watch out: There is no amputation-alone arm in this trial: the P < .001 comparison is against previously reported (historical) amputation-alone results, which are vulnerable to era, referral-population and staging differences. This card supports the platinum story's consistency — a second platinum agent, median survival in the same range as the cisplatin groups in Straw 1991 — it does not independently prove the benefit.
Bergman PJ, MacEwen EG, Kurzman ID, Henry CJ, Hammer AS, Knapp DW, Hale A, Kruth SA, Klein MK, Klausner J, Norris AM, McCaw D, Straw RC, Withrow SJ. Amputation and carboplatin for treatment of dogs with osteosarcoma: 48 cases (1991 to 1993). J Vet Intern Med. 1996;10(2):76-81. PMID: 8683484. Registry ID: none in the record. MeSH: Amputation, Surgical · Animals · Antineoplastic Agents/therapeutic use · Bone Neoplasms/therapy,veterinary · Carboplatin/therapeutic use · Combined Modality Therapy · Dog Diseases/therapy · Dogs · Female · Male · Osteosarcoma/therapy,veterinary · Prognosis · Prospective Studies · Survival Analysis
Skorupski 2016 (randomised, phase III): six doses of carboplatin gave a longer disease-free interval than alternating carboplatin/doxorubicin (425 vs 135 days, P = 0.04)
Randomized, phase III trial (record's own title wording); publication type Randomized Controlled Trial; blinding not stated
Who: Dogs: 50 dogs with histologically confirmed appendicular osteosarcoma, free of gross metastases, in a clinical trial setting after amputation of the affected limb, randomised to receive either six doses of carboplatin or three doses each of carboplatin and doxorubicin on an alternating schedule.
Result: Dogs receiving carboplatin alone had a significantly longer disease-free interval (425 days) than dogs receiving alternating carboplatin and doxorubicin (135 days) (P = 0.04). Toxicity was similar between groups. The authors suggest six doses of carboplatin may be associated with a superior disease-free interval compared with six total doses of carboplatin and doxorubicin.
Watch out: This trial answers a different question — which platinum-containing regimen, not chemotherapy vs none: every dog received chemotherapy, so it cannot carry the vs-amputation-alone claim. It is carded because it is the randomised evidence on the platinum backbone itself (and because its carboplatin-alone disease-free interval, 425 days, sits well above the amputation-alone survival figures on this shelf). The record does not state blinding, and none is claimed.
Skorupski KA, Uhl JM, Szivek A, Allstadt Frazier SD, Rebhun RB, Rodriguez CO. Carboplatin versus alternating carboplatin and doxorubicin for the adjuvant treatment of canine appendicular osteosarcoma: a randomized, phase III trial. Vet Comp Oncol. 2016;14(1):81-7. PMID: 24118677. Registry ID: none in the record. MeSH: Animals · Antineoplastic Agents/administration & dosage,therapeutic use · Bone Neoplasms/drug therapy,veterinary · Carboplatin/administration & dosage,therapeutic use · Chemotherapy, Adjuvant · Dog Diseases/drug therapy · Dogs · Doxorubicin/administration & dosage,therapeutic use · Osteosarcoma/drug therapy,veterinary
Synthesis: platinum chemotherapy after amputation is associated with roughly doubled median survival, on non-randomised comparisons — no randomised vs-amputation-alone trial exists in these records
Synthesis
Who: Synthesis of the cards above: Straw 1991 (71 dogs, non-randomised three-group comparison: cisplatin after, cisplatin before + after, or amputation alone), Bergman 1996 (48 dogs, prospective single-arm carboplatin with historical amputation-alone comparison) and Skorupski 2016 (50 dogs, randomised phase III, carboplatin vs alternating carboplatin/doxorubicin, no untreated arm).
Result: Across the comparisons: median survival was 262 days (cisplatin after amputation) and 282 days (cisplatin before + after) vs 119 days for amputation alone (Straw 1991, difference reported significant); median survival was 321 days with carboplatin, 35.4% alive at 1 year, reported longer than historical amputation-alone results at P < .001 (Bergman 1996); and among chemotherapy regimens, six-dose carboplatin gave a disease-free interval of 425 vs 135 days against an alternating regimen (Skorupski 2016, P = 0.04). Every vs-no-chemotherapy comparison points the same way with a large margin; none of them is randomised.
Watch out: The gap this shelf cannot close: dogs offered and able to complete chemotherapy may differ systematically (health, staging, owner resources) from dogs treated by amputation alone, and neither Straw 1991 nor the historical comparison in Bergman 1996 can remove that bias. The survival claim is Tier C and rests for display on John's personal ruling.
Synthesis of Straw RC et al. PMID: 1941754; Bergman PJ et al. PMID: 8683484; Skorupski KA et al. PMID: 24118677. Registry IDs as on the individual cards.
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