Summit on Oncology

Excerpts concerning Vaccine-Associated Sarcomas

Updated for fall '98 By Dr. Alice Villalobos from Veterinary Forum Magazine, December 1997

The Cancer-Vaccine Connection

Inflammation at vaccine sites is now known to be a promoter of cancer in cats. Debate over this fact heated up lots of controversy reminiscent of the heated debates of the 1970's concerning the Feline Leukemia Virus. At that time, the question was whether to kill or not to kill positive cats. Now with vaccine associated sarcomas, the controversial question is whether to vaccinate or not over vaccinate indoor cats.

Dr. Niels Pedersen of UCD pointed out that cats are genetically very similar so that universally, we are treating one creature. If the feline fibroblast is susceptible to inflammation as a promoter of cancer, then cats that develop vaccine lumps, inflammatory bowel disease, gingivitis, and solar dermatitis are more at risk. Cats with the above conditions are more susceptible to cancer because all these conditions cause rearrangements or translocations of genes.

In a shocking lecture, at the 1997 AAHA meeting, Dr. Pedersen eloquently stated "Vaccination as a Medically vs. Economically Based Procedure." In his opinion (based on questions asked of many veterinarians and pet owners), the procedure of vaccination has been taken into the economic and guilt realm almost like an addiction without sound medical judgement or the original valued purpose of the annual physical exam. He stressed that each veterinarian must thoroughly exam and medically evaluate cats and dogs and look at the risk benefit ratio for vaccinations and individualize each case. He said that multivalent vaccines take the choice away from the doctor and that they are not needed on a yearly basis after the puppy and kitten series. He pointed out that companies manufacture vaccines against every disease out there and they market them whether needed or not and we use them by justifying them is some way or another. If you would like to order a copy of this lecture tape, please call (800)-776-5454.

Axioms

Dr. Greg Ogilvie of CSU lectures enthusiastically all around the country. He gets his audience to chant, "The 3 Golden Rules of Oncology are Biopsy, Biopsy, Biopsy!" He had doctors reciting, "Do not whittle or mutilate tumors!" and, "A chance to cut is a chance to cure or help your radiation therapist!" I feel that it is crucial to do a find needle aspirate cytology or a true cut biopsy BEFORE surgery if the diagnosis would make a difference on the approach and aggressiveness of the first surgery. This precaution reduces the calamity of dirty margins, the need for a second definitive surgery and recurrence.

Multimodality Treatment for Sarcomas

Soft tissue sarcomas cover a large number of tumors that we see in practice. Survival is best if we get a clean 3-cm surgical margin, so a presurgical plan is very important.

If you know you cannot attain a 3-cm margin, the case should be referred to a surgical oncologist who can. Young boys who get Ewing's sarcomas on their thighs have a 60-90% recurrence rate with surgery alone. Radiation and chemotherapy help reduce recurrence and increase limb salvage for these boys. In pets and especially in cats with vaccine associated sarcoma, the issue is whether the radiation should be given before Sx or after Sx. There are pro and con viewpoints on both sides.

The AVMA, AAHA and the VCS have task force committees to study vaccine associated sarcomas. Incidence data is still controversial. Some doctors claim they do not see these sarcomas while Dr. David Langford, in Maryland, had two cases in unrelated cats in the same household!.

We must do more than aggressive surgery on most sarcomas. If the biopsy shows a low grade tumor with wide margins, we may not have to worry. Medium, moderate or high grade tumors are persistent. Even with follow up radiation, the recurrence rate reported by most institutions is 50% within a year. These poor data force the use of multimodality Tx and initially more aggressive, imaginative protocols with sequencing therapy. This is why some feel that pre or intraoperative RTX is worth pursuing alongside chemotherapy in a multimodality setting. Observations from an initial series of vaccine associated sarcomas treated at the Animal Cancer Center, in Hermosa Beach, CA, show a 33% recurrence rate in one year. Intraoperative radiation therapy and chemotherapy as implants and adjuvants were used. The study now involves more cases and is very encouraging (see figure 2). Other centers are expected to publish data in the very near future which may lay guidelines to optimum therapy.

Figure 2. Results of ACC study using multimodality therapy on vaccine associated sarcomas (VAS), demonstrating an increased tumor-free interval and survival in 9 of 13 cats. "Lady" O' Connor is case #12 in this study and is tumor free from VAS for 3 years.

Aggressive Sarcoma Protocol

Intraoperative radiation (IOP RTX) with chemotherapy implant enhancement is probably the most aggressive immediate being used on sarcomas in the U.S.A. today. Observations suggest that tumor bed implants with carboplatinum in cats or cisplatinum in dogs and IOP RTX may actually decrease the amount of fibroblastic growth factors at the healing surgical site. Growth factors stimulate tumor cells to proliferate rapidly following surgery. It may be that IOP RTX increases long term remissions and survival in animals with sarcomas of any histologic type because radiation therapy is delivered during surgery directly into the open tumor bed.

Mitoxantrone, adriamycin or carboplatinum are used as radiation therapy enhancers every three weeks for three to six treatments. CBC's are taken prior to chemotherapy. Supportive care and Neupogen are given as needed. Ten fractions of external beam radiation therapy are given to total 5,000 - 5,600 cGy to the tumor field over a five week period starting 7-14 days post IOP RTX. Hair regrows a lighter color after 90 days. Decisions made at the start of any cancer often determine the chances of success. If a sarcoma is high grade, over 2cm or recurrent, a referral is indicated... Money and distance are often not the problem.

Note:

If you any questions regarding a pet with cancer, please don't hesitate to call :

VCA Coast Animal Hospital and Cancer Center

1560 Pacific Coast Highway

Hermosa Beach, CA 90254

1-800-540-VETS

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