Advances in medical oncology

The specialty of medical oncology has traditionally been characterized by steady, incremental gains in the efficacy of therapy and only rarely by startling breakthroughs. This is as true in veterinary medical oncology as it is in the human specialty. The past decade in veterinary medical oncology has produced modest advances in the treatment of several cancers. We have added new compounds to our therapeutic arsenal and refined the use of standard anticancer chemotherapy drugs through improvements in dose and scheduling of combination therapy. Early intervention has contributed to this increased treatment success. Improved diagnostics, better understanding of the biologic behavior of individual tumors provided by new prognostic and predictive markers, and an attitudinal shift in the minds of veterinary practitioners and the pet owning public have all contributed to increased success in medical oncology. Patient outcomes have also been improved through refinements in multimodality therapy, combining the expertise of specialists in medical, radiation, and surgical oncology. This issue of Veterinary Clinics of North America: Small Animal Practice presents updated information on the treatment of the diseases commonly encountered in veterinary oncology. I hope that the information provided will prove useful to students, specialists in training, and practitioners.

The commonly encountered tumors that impair the longevity and quality of life of our patients are reviewed in the chapters by Drs. Fan, London, Chun and de Lorimier, Rassnick, Smith, Hauck, Sorenmo, Henry, and Klein. A great deal of the information in their reviews of the literature was garnered from individual case reports, small case series, and retrospective studies. I am sure these authors would agree that there is an urgent need for prospective, appropriately blinded and randomized trials in veterinary medical oncology. In the past few years, the first large industry sponsored multi-center trial with intent to achieve veterinary drug licensing was conducted, and more such trials are ongoing or planned. The organization of multi-center trial groups in the US, as well as the move into prospective work by the venerable Veterinary Cooperative Oncology Group, promises to speed progress in our specialty. The conduct of well-designed and ethically conducted prospective trials is critical to our future.

Recent publications and abstracts describing the use of several agents new to veterinary oncology are summarized here. The reader is advised to consult veterinary medical oncology specialists for new information and guidance regarding the use of these compounds. Clients should be informed of the off-label status of all anticancer chemotherapy agents used in veterinary medicine, and appropriate biosafety precautions should be emphasized for all who come in contact with these drugs. Improved understanding of the mechanisms of drug resistance provided by Dr. Phil Bergman's chapter may prove helpful in explaining individual case outcomes and in defining future directions for therapy.

The past decade has seen molecularly targeted therapeutic approaches advance as an intense focus in human medicine, with new compounds developed through research in traditional pharmacology, recombinant biologics, and immunotherapy. Some of these novel agents have changed the standard of care for human patients with disseminated cancers, and more hold promise in the near future. The exquisitely selective nature of molecular targeting permits enhanced efficacy while limiting adverse effects. Unfortunately, it is this precise selectivity in molecular targeting that makes the translational use of these agents in clinical companion animal practice difficult, if not impossible. The coming decade will be a challenging and exciting one for veterinary medical oncology as we begin to move enthusiastically into this new field. Clearly, we have work to do.

I wish to thank all of the contributors for the their thorough and thoughtful reviews. The residents in medical oncology at the University of Illinois, especially Louis-Philippe de Lorimier and Amy Wiedemann, were invaluable for editorial input regarding both content and style. Finally, John Vassallo at W.B. Saunders is a man of formidable patience, good humor, and editorial skill. I owe him abundant thanks, a drink, and a case of Maalox for putting up with me.