Advances in Canine Cancer: Lymphoma

What is Lymphoma?

Lymphoma is cancer that begins in cells of the immune system found in lymph nodes. Lymphoma accounts for approximately up to 20% of all canine cancer and 80% of all canine blood cell malignancies. Lymphoma is generally seen in older dogs (median age, 6-9 years).

Lymphoma progresses over time and is “staged” based on its degree of metastasis and invasiveness. They are as follows:

• Stage I: Ailment restricted to a single lymph node
• Stage II: Regional lymphadenopathy (restricted to one location or region)
• Stage III: Generalized lymphadenopathy (wide spread enlargement of lymph nodes)
• Stage IV: Enlargement of the liver and spleen or hepatosplenomegaly (with or without lymphadenopathy)
• Stage V: Bone marrow, CNS (Central Nervous System), or involvement of other extra nodal sites due to metastasis

The Past

Development of new drugs for treatment of lymphoma has been mostly empiric, with a limited knowledge of the molecular background of the tumor, the involvement of multiple molecular targets in disease pathogenesis, and ultimately the effect of the drug on the target and thus the patient. The variability observed in responsiveness to treatment was likely the result of the heterogeneity of the underlying molecular mechanism responsible for the individual cancer.

What is the current state of lymphoma research?

Thanks to advances in molecular biology, lymphoma research has made exponential progress in the last decade. We now know that the cells involved in lymphoma are phenotypically different from patient to patient even though they may be of the same hematopoietic lineage.  And most importantly, we have learned the cells are molecularly heterogeneous, meaning the tumor cells differ in genetic makeup across individuals. What does this mean for curing and preventing cancer in the dog? Although it appears we will not have a “one gene” causative agent and the problem is more complicated than originally thought, there is a great deal of power in these findings that gives us hope.

The Future: Personalized Medicine

Knowledge is power because we now know a “one size-fits all” treatment strategy is not optimal. We are moving towards integration of the genetics of the individual with the genetics of the tumor to make informed treatment decisions. What will be the outcome? Clinicians will be able to make informed, cost-effective decisions about treatment that will increase the likelihood a tumor will respond and a dog will defeat cancer.

How will we meet this challenge?

In February 2015, the AKC Canine Health Foundation released a cancer-focused request for proposals that asks researchers to respond to the challenges of integrating tumor-specific biomarkers, genetic information and drug targets into practical personalized medicine plans for patients. We asked for both clinical trial focused studies to put into practice what we already know, and basic science studies to fill those gaps in knowledge that are holding us back. Not only will biomarker-driven personalized medicine become a reality in the cure and management of this disease, but data will ultimately allow breeders to have a deeper knowledge about their lines and make informed decisions to avoid this dreaded disease.