Happy Monday!

Instead of posting pictures of the little Chihuahua ("Stevie") on the blog, it's better to go to our website www.veterinarycancer.com and view the video! Little Stevie is doing great post-operatively and was adopted by my mother and dad!! He's enjoying the love and attention and every day becomes more lovable.

Exploring better options: Chemotherapy protocols for diseases such as lymphoma and osteosarcoma have not changed significantly in over 20 years, nor have the median survival times despite the addition of new drugs. In an attempt to investigate new ways of giving chemotherapy, we are now routinely using metronomic (low dose) chemotherapy for a variety of tumors at ACIC, including hemangiosarcoma and osteosarcoma.

What exactly is metronomic chemotherapy?

“The definition of metronomic chemotherapy varies, but generally it refers to repetitive, low doses of chemotherapy drugs designed to minimize toxicity and target the endothelium or tumor stroma as opposed to targeting the tumor.” ...Dr. Harold Burstein of the Dana-Farber Cancer Institute.

An excellent basic description of metronomic chemotherapy comes from Dr. Robert S. Kerbel, one of the leaders in this field of metastasis and anti-angiogenesis who is highly regarded for discoveries that are helping to improve cancer therapies and the quality of life of cancer patients:

“For almost half a century, systemic therapy of cancer has been dominated by the use of cytotoxic chemotherapeutics. Most of these drugs are DNA-damaging agents that are designed to inhibit or kill rapidly dividing cells. They are often administered in single doses or short courses of therapy at the highest possible dosage without causing life-threatening levels of toxicity. This is referred to as the “Maximum Tolerated Dose” (MTD). MTD therapy requires prolonged breaks (generally 2-3 weeks in duration) between successive cycles of therapy. Progress had been modest in terms of curing or significantly prolonging the lives of patients with cancer using MTD—particularly those with advanced-stage or metastatic disease. The higher the dosage of chemotherapy, the more likely we are to kill the cancer, but the limiting factor is always the adverse side effects that occur with increasing dosages. More recently, a lot of research has been directed towards a reappraisal of the best ways of administering chemotherapy. Instead of using short bursts of toxic MTD chemotherapy interspersed with long breaks to allow recovery from the harmful side effects, there is now a shift in thinking towards the view that more compressed or accelerated schedules of drug administration using much smaller dosages than MTD might be more effective—not only in terms of reducing certain toxicities but perhaps even improving antitumor effects as well.” (Kerbel RS and Kamen BA, The Anti-Angiogenic Basis of Metronomic Chemotherapy, Nature Reviews Cancer 2004.)

In dogs and cats, we utilize chemotherapy agents such as cyclophosphamide at dosages approximately one-tenth of standard MTD dosages. These drugs are given daily to every other day. We have been using metronomic therapy for over 2 years and have experienced negligible side effects. Metronomic chemotherapy appears to be as effective as MTD (Adriamycin in this case) in dogs treated for hemangiosarcoma. Studies have also shown that metronomic chemotherapy may be effective in delaying recurrence of incompletely excised soft tissue sarcomas (STS). Of course, more aggressive surgery or radiation therapy is most effective in the setting of incompletely excised STS, but metronomic chemotherapy could provide a reasonable alternative for pet owners who cannot afford surgery or radiation.