Oncology and Radiation Therapy

Radiation Therapy at Vetspecs

In April 2011, we announced the ability of Vetspecs to offer radiation therapy (RT) to the New Zealand-wide veterinary population utilising a sophisticated and state of the art linear accelerator (linac) situated at the St George’s Cancer Care Centre (SGCCC) here in Christchurch.  We are incredibly grateful to the skilled and compassionate team at the SGCCC who have facilitated this special and precious relationship with Vetspecs.  So far we have been privileged to treat four patients, we have had many enquiries about the service and have seen many more that were good candidates for RT.  

RT is now accepted as a principal way of treating cancer in humans and veterinary patients.  In North America, Europe and Australia, the availability of RT has increased substantially for animals over the last 20 years.  In New Zealand, we have certainly lagged behind the rest of the world; the reasons are not due to a lack of medical indications but, perhaps not unexpectedly, due to expense and lack of available expertise in our wonderful but small country.  However, we are excited to state that times have changed!

Linacs are capable of delivering very high-energy radiation beams for very precise and consistent treatment of tumours.  Like any medical intervention, we are always faced with a balancing act of maximal efficacy against a disease process and minimal adverse effects.  The sophisticated planning by the SGCCC team and their exquisite equipment focuses on balancing this equation such that normal cells are minimally exposed to radiation and can repair themselves whilst tumour cells are preferentially sterilised. 

In the 1920s, it was realised that RT is more effective and better tolerated when the radiation dose is delivered in small but numerous treatments compared to giving the same dose all at once.  This is known as fractionation and it helps spare normal tissue whilst simultaneously controlling tumour cells. In general, RT efficacy is optimised when as high a dose as possible is delivered in multiple fractions over the shortest possible time.  This fact forms the basis of our fractionation schemes but variations arise based on tumour biology and intent (curative or palliative). 

At Vetspecs, we are fortunate to have some wonderful support from veterinary neurologists, veterinary oncologists and veterinary radiation oncologists in North America and Australia.  Skype, emails and the internet make the world a small place!  Case details, including advanced imaging (CT and or MRI) files, are viewed remotely by these specialists and they provide us with invaluable information on the most current treatment thoughts pertaining to the case on hand.   This includes discussion on surgery, chemotherapy and or RT and, where combination therapies are to be instigated, the timing of each with respect to the other – that is, optimal adjuvant (after surgery) and neoadjuvant (before surgery) strategies. 

With our “RT recipe” in hand, we contact the amazing team at SGCCC for a treatment quote and to arrange an initial planning CT.  This necessitates attendance at the centre during which the patient is sedated and placed into a mouldable vacuum bag.  This customised ‘vac bag’ is re-used for every subsequent RT session that particular patient attends.  CT and or MRI images are combined with treatment planning software to produce complex treatment plans utilising multiple beam energies and precisely shaped treatment fields.  The RT dosing starts approximately a week following the planning CT and, before every RT session, the area in question is re-imaged to ensure correct alignments of the radiation beams.    Typically, curative intent treatments entail daily (Monday-Friday) dosing over 3-4weeks whilst palliative protocols are weekly over 4-6weeks.  For adjuvant RT, the timing between surgery and RT can be very important to the outcome so, for cases in which you are considering performing surgery first, please contact Vetspecs ahead of time due to the planning that is needed before we can start RT. 

RT is the treatment of choice for many tumour types.  The best examples are probably nasal and brain tumours.  RT should be considered in post-surgical situations when a pathology report reveals a close or incomplete resection; RT may be effective in preventing recurrence in the same location and or prolonging the disease free interval.  Mast cell tumours and soft tissues sarcomas are good examples of this adjuvant use of RT.  Similarly, some tumours may be deemed non-resectable and RT may be a viable alternative or permit a previously non-resectable mass to be surgically removed.  Osteosarcomas are known to be very painful conditions and palliative RT can help provide effective analgesia.

We have established that there are many clinical indications for RT, that our RT knowledge is advanced and developed by a collaborative, international and multi-specialist approach and that we have access to the most state of the art facility here in Christchurch.  So, why have we only proceeded with 4 patients?  Well, the simple answer is cost.  RT is not inexpensive.  For a ‘simple’ superficial skin cancer, treatment costs may be as low as $2000 and, for palliative symptom control, estimates are likely to be in the region of $3000.  However, for complex and curative-intent treatments, we may have to consider fees of $8000-12,000.  Hence, we can understand that many owners will find this cost prohibitive. Regardless, we owe it to our clients to inform them of all their options.  Similarly, pet insurance uptake should be increasingly encouraged. 

Please contact Vetspecs if you have cases you would like to discuss.  The field of RT is expanding and we are living in exciting times.  The ability to offer more to our worthy patients is a thrilling reality.