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Everything else

All the stuff we didn’t have a place for.

In anticipation of the upcoming WebinarVet Virtual Veterinary Conference 2023 in February, I have been revisiting some previous webinars of some of the speakers that are lined up. It gives a good indication of what to expect and first up is Douglas Thamm. He has authored over 150 peer-reviewed publications, 20 book chapters, and is co author of a standard text in small animal oncology and co-editor in chief of Veterinary and Comparative Oncology. Comparative oncology is a main interest and his research includes targeted therapies for animal and human cancer.

DOUGLAS H THAMM VMD DACVIM PROFESSOR OF ONCOLOGY ANIMAL CANCER CENTER COLORADO STATE UNIVERSITY VETERINARY TEACHING HOSPITAL dthamm@colostate.edu

There is a great deal more information to be found about his career to date by clicking on Dr Doug Thamm Flint Animal Cancer Center. This account of a CV is one of the most inspirational I have read and he starts by saying ‘My wife and I are actually both cancer survivors.’ He goes on to detail the journey leading to a cure, which in his case needed a year out of his studies. This, no doubt, made his choice of a specialty almost inevitable and immediately after graduation he undertook a residency in oncology, and subsequently joining Colorado State University in 2004. He was immediately ‘blown away’ by the wonderful and unique sense of family that is present there. People welcoming, genuinely liking each other-‘it’s like a breath of fresh air coming to a place like this, where everybody is so friendly and gets along so well. I love coming to work each day.’ There must be many lessons to be learned from him and his institution, not just in oncology but also how to be happy in these troubling times for the profession. .

I mention all this because Doug clearly genuinely loves teaching, and it shines across in this webinar and others he has contributed. He speaks very clearly without hurrying or using jargon, greatly benefitting colleagues whose first language is not English. He actively welcomes questions too and you can contact him via the email above.

If you haven’t watched this webinar on soft tissue sarcomas it is an excellent example of Doug’s style of teaching, and I will summarise briefly what he covers.

After demystifying the nomenclature involving 12 soft tissue sarcomas he describes typical clinical presentations and biological behaviour. A couple of photos of a maxilla tumour on a retriever warn that in this breed such tumours are very benign on histology. This risks a pathological diagnosis of fibroma, reactive fibroplasia, for example, whereas tumours in this location and breed are very invasive, commonly recur and can metastasise. Being aware of the tumour and crucially helping our pathologists out by accurate form filling including breed, location etc. is obviously important to minimise the risk of an incorrect diagnosis.

Diagnostic staging is described with fine needle aspiration, biopsy (incisional, punch, tru-cut and wedge) and excisional for diagnostic purposes. These are all briefly covered with some excellent clinical photos of cytology and some tips to get the best possible results. As a part of staging thoracic radiographs are useful, since although the metastatic rate is low it is not zero. A radiograph proves the point. Similarly a FNA of regional lymph nodes is worthwhile, since although lymph node metastasis is less common compared to other histiocytes, it is certainly seen.

Aggressive treatment is the mainstay of treatment with 3 cm margins in all directions, and identifying margins for histopathological assessment. A simple line diagram, of use in client education, illustrates the importance of deep 3 cm margins. Radical procedures may be necessary such as amputation, body wall resection, and mandibulectomy may be necessary. The best chance to cure is with the first surgery.

Interpreting the pathology report is equally important, particularly the grade (you are reminded to ensure that you ask for this).

There is a very good series of slides summarising radiation therapy, stated to be much more effective when treating microscopic disease, and there are some interesting survival statistics. Some of the ‘down sides’ to radiation therapy are mentioned. There may be local mild to severe reactions, multiple general anaesthesia procedures may be required and hospitalisation time is increased.

The indications for chemotherapy are listed and there is detail, including doses and timing intervals, on three protocols. These are doxorubicin alone, doxorubicin with cyclophosphamide, and doxorubicin with cyclophosphamide and vincristine. Other protocols are mentioned with reference to the relevant literature, as well as a description of metronomic therapy. This section is of particular interest to specialists in training.

The final part of the webinar deals with Vaccine Associated Sarcoma in cats. This is almost a stand-alone webinar as it is quite comprehensive. The incidence of between 1 in 3000 and 10,000 vaccines is noted, with chronic inflammation a factor. Many other injectables including microchips have also been incriminated. Thus the term Injection Site Sarcomais now preferred. There is a variable onset post-injection from a few months to more than 3 years. The tumour is histologically and biologically aggressive, and there is a variable metastatic rate of 5-25% (depending on which study you read).

Surgical removal is the mainstay of treatment and this needs to be aggressive/radical. This has been shown to result in a better outcome, with a mean survival of 325 days compared to 79 days with conservative surgery. Cats with tumours on the limbs treated with amputation have a very high cure rate.

The role of radiation therapy, including stereotactic body radiation therapy is described with some encouraging statistics for median disease free intervals and median survival time. Various drugs used in chemotherapy are listed together with their percentage response rate and survival times

The final slides detail prevention and education: 

  • Limit vaccine frequency –titres?
  • Vaccine location, Avoid multiple vaccines in the same site, use alternate routes, and possibly non-adjuvanted products
  • In the United States where rabies vaccine exists there is advice to inject in the following sites.
  • Rabies RH
  • Leukaemia LH
  • FVRCP RF
  • Owner education for monitoring –notify vet if: – (3-2-1 Rule)
  • The tumour persists for more than 3 months after vaccination
  • It becomes larger than 2 cm in diameter
  • It is increasing in size 1 month after vaccination

This excellent veterinary webinar is highly recommended as a comprehensive update in soft tissue sarcomas. It will set you up for Doug Thamm’s presentation in the 2023 Virtual Congress

The Top Ten List: 10 Recent Advances in Veterinary Oncology

Monday 6th. February 19:00-20:00