Lymphoma is one of the most common cancers in dogs, and for years, veterinarians have relied on CHOP-based chemotherapy protocols as the gold standard for treating peripheral nodal B-cell lymphomas (PNBCL). Two protocols—CHOP-19 and CHOP-25—are frequently prescribed, but until now, they had never been directly compared. A recent study sought to settle the debate and determine if one protocol offers better outcomes for canine lymphoma patients.

The Study: Comparing CHOP-19 and CHOP-25 In this multicenter, retrospective cohort study, 502 dogs from 16 European oncology referral centers were treated with either the CHOP-19 or CHOP-25 protocol for PNBCL. The CHOP protocol includes a combination of cyclophosphamide, hydroxydaunorubicin (doxorubicin), Oncovin (vincristine), and prednisolone. CHOP-19 involves 19 weeks of treatment, while CHOP-25 extends the treatment period to 25 weeks.

The primary goal was to compare the progression-free survival (PFS) and overall survival (OS) of dogs treated with each protocol. Additionally, the study examined whether any protocol-related factors influenced the outcomes.

Key Findings: Minimal Difference Between the Protocols

• Progression-Free Survival (PFS):

  • CHOP-19: 6-month PFS of 56.5%, 1-year PFS of 14.1%, and a median PFS of 196 days.

  • CHOP-25: 6-month PFS of 56.4%, 1-year PFS of 17%, and a median PFS of 209 days.

• Overall Survival (OS):

  • CHOP-19: 1-year OS of 36.9%, 2-year OS of 13.5%, and a median OS of 302 days.

  • CHOP-25: 1-year OS of 42.8%, 2-year OS of 15.4%, and a median OS of 321 days.

Despite slight variations, there was no significant difference in the outcomes between the two protocols. Both CHOP-19 and CHOP-25 provided similar PFS and OS rates, suggesting that either can be effectively used as a first-line treatment option for dogs with PNBCL.

Conclusion: Both Protocols Are Effective The study concluded that both CHOP-19 and CHOP-25 protocols are viable options for treating PNBCL in dogs, with no clear advantage of one over the other in terms of progression-free or overall survival. This means that veterinarians can confidently use either protocol depending on the patient’s needs or the clinic’s preference.

Clinical Relevance: Choosing the Right Protocol for Your Dog For pet owners facing a lymphoma diagnosis in their dog, this study offers some reassurance: both CHOP-19 and CHOP-25 provide similar outcomes, allowing for flexibility in treatment decisions. The ability to choose between a shorter (CHOP-19) or longer (CHOP-25) course of chemotherapy without compromising the chances of survival is a significant finding for veterinary oncology.

Moving forward, both protocols will continue to be used as a standard of care in future trials, helping dogs with lymphoma fight their battle with cancer.

Read full study here: Comparison of CHOP-19 and CHOP-25 for treatment of peripheral nodal B-cell lymphoma in dogs: A European multicenter retrospective cohort study