Traditionally, Squamous cell carcinomas (SCC) is removed by surgical procedures. This can be an effective treatment, but it can be difficult to get good surgical margins and therefore recurrence and spread to lymph nodes remains a risk. Other treatments are often given alongside surgical removal (or instead of surgery if this is not possible). These are usually topical chemotherapy agents that are applied onto or injected into the tumours, or radiotherapy. Radiotherapy has several advantages over topical treatments, and is now available at the Animal Health Trust.
The most effective form of radiotherapy for most superficial SCC is called strontium plesiotherapy. Strontium plesiotherapy involves the direct application of a radioactive source to the tumour surface. The major advantage is that the type of radiation emitted penetrates only a few millimeters, meaning that a large dose of radiation can be applied to the surface without adversely affecting deep tissues. This means that the tumour tissue is destroyed, but delicate surrounding structures (such as the eye) are not affected.
Strontium plesiotherapy has been successfully used in the treatment of tumours located in many difficult areas in dogs, cats, and horses and represents a real advance in the treatment of these lesions. Strontium may be performed under standing sedation in some locations, and under a short general anaesthetic for others. Depending on the size of the tumour, treatments are usually given in 3 sessions, spaced 48 hours apart. Each treatment takes around 5-10 minutes depending on the size of the area being treated, and between treatments the horse can be treated as normal. This treatment is suitable for both tumours that cannot be surgically removed and those that have been removed with small or ‘dirty’ margins, and can also be used to treat some other types of skin cancers in the horse.
The AHT is currently the only veterinary clinic in the UK that can provide strontium plesiotherapy treatment.