Timing of Chemotherapy Following Amputation in Dogs with Osteosarcoma

ArticleLast Updated May 20222 min read
Print/View PDF
featured image

In the literature

Marconato L, Buracco P, Polton GA, et al. Timing of adjuvant chemotherapy after limb amputation and effect on outcome in dogs with appendicular osteosarcoma without distant metastases. J Am Vet Med Assoc. 2021;259(7):749-756.

The Research ...

Adjuvant chemotherapy following limb amputation in dogs with osteosarcoma can be beneficial, but optimal timing for administration is unknown. In dogs, chemotherapy is commonly initiated at the time of suture removal; this is in contrast to humans, in which a neoadjuvant multiagent protocol is used before surgery for the primary lesion.1,2 

This retrospective, multicenter study of 168 dogs was designed to determine the optimal interval between amputation and administration of chemotherapy, as well as to determine the effect on disease progression and overall survival time. Patients received different chemotherapy protocols at various time points (1-30+ days) following amputation surgery. 

Findings suggested that dogs treated sooner after amputation had both longer median times to progression and longer overall median survival times. Differences were most marked between dogs receiving chemotherapy ≤5 days and >5 days (median overall survival time, 445 and 239 days, respectively) after amputation. 

Incidence of chemotherapy grade 3 and 4 toxic effects did not increase in patients that received chemotherapy within 5 days of surgery. Dogs that received chemotherapy after >30 days had median time to progression of 136 days and overall median survival time of 169 days, similar to dogs treated with amputation alone.3 Longer duration of clinical signs (>28 days) prior to diagnosis also increased the risk for nonsurvival.

Osteosarcoma treatment outcomes have been static, with different chemotherapy protocols resulting in similar overall survival times. Findings of this study support the need for further prospective research of the timing of chemotherapy and its relation to patient outcome. Changes in the timing of chemotherapy may lead to improvements in outcome.

...The Takeaways

Key pearls to put into practice:

  • Older dogs may be presented for new or worsening lameness or limb swelling that could indicate an underlying primary bone tumor. Radiography is warranted to investigate and rule out bone pathology.

  • Earlier diagnosis of appendicular osteosarcoma may help improve survival times following definitive treatment of amputation and chemotherapy.

  • Timing of chemotherapy following limb amputation in dogs with osteosarcoma may affect progression-free interval and survival times. Prolonged delay in initiation of chemotherapy following amputation can lead to shorter survival times.