What is stereotactic radiation (SRS/SRT)? How does it work?
SRS/SRT, short for stereotactic radiosurgery or stereotactic radiation therapy, is a new way to deliver advanced radiation therapy. It is nonsurgical and significantly reduces the number of treatment sessions and anesthetic events typically associated with radiation therapy. It has been proven effective in human health care and is now offered in veterinary medicine through PetCure Oncology’s national network of cancer care partnerships. SRS/SRT delivers 1-3 high doses of radiation to tumors with submillimeter precision. The unprecedented precision optimizes impact on the tumor while minimizing collateral damage to nearby healthy tissue, often leading to a decrease in the duration and intensity of side effects. SRS/SRT treatment by PetCure is delivered in just 1-3 sessions – 80-95% less than traditional radiation therapy – which has the added benefits of decreasing risk and expense while increasing convenience and efficiency for the pet owner.
What kind of tumors can SRS/SRT treat? Can’t traditional radiation therapy treat the same things?
SRS/SRT can be used to treat any tumor or localized cancer. In many instances, this includes cases that are otherwise deemed to be inoperable through surgery or too dangerous to treat with traditional radiation therapy. Tumors in the brain, nasal or prostate, as well as mast cells or osteosarcomas, for example, can be difficult to treat when in close proximity to vital organs due to the danger of collateral damage. The submillimeter precision of SRS/SRT, however, allows for the tumor to be directly targeted – even if partially embedded in healthy tissue – with minimal damage to surrounding healthy tissue.
PetCure Oncology can now also treat post-surgical cases where the pet still has traces of cancer. A successful clinical trial proved the efficacy and safety of this new method, which uses a liquid fiducial to artificially create a target volume within the surgical cavity. The artificial mass provides the necessary target to create an SRS/SRT treatment plan, enabling post-surgical pets that still have cancer to receive targeted treatment that would otherwise be unattainable.
Are the side effects of SRS/SRT similar to traditional radiation therapy?
No. Two of the primary reasons that pet owners shy away from traditional radiation therapy are the strain on the pet over the course of numerous treatment sessions and the complications or side effects commonly associated with low-dose, high-fractionated therapy. SRS/SRT significantly reduces the strain on the pet during treatment as well as the chances and duration of side effects post-treatment by the very nature of a highly targeted, 1-3 fraction treatment course (high-dose, low-fraction). Many patients experience no worse than some discoloration of the fur on the treatment site or minor inflammation. A smaller number of patients will have adverse reactions. Typically, a pet will return to normal activities immediately following treatment with a much-improved quality of life.
Is there any research or data on SRS/SRT outcomes?
Yes. SRS/SRT has been used in human medicine since 1950 for intracranial conditions and since the early 2000’s for extracranial conditions. A significant body of research has been published over that time. Most of the long-term data is derived from human studies, where SRS/SRT has shown results significantly better than those achieved with conventionally fractionated protocols, with far fewer side effects. Making the transition from human therapy to pet therapy is based on well-founded principles of radiobiology, and preliminary data has shown that the application of human SRS/SRT standards and protocols within veterinary medicine has generated similar outcomes.
Having treated more than 3,500 pets with radiation therapy since 2015, including more than 2,500 with SRS/SRT, PetCure Oncology is in a unique position to analyze large numbers of pets, all treated on-protocol, and evaluate safety and efficacy. This effort is supported by an independent Scientific Advisory Board that includes board-certified human and veterinary oncologists as well as experts in medical physics. Conducting and sharing this clinical research with the veterinary community is a core function of PetCure’s mission.
Preliminary data analyses indicate that pets treated with SRS/SRT under PetCure protocols have shown similar or better survival times than current standard-of-care treatments for numerous tumor types. As each tumor type’s data set matures, the outcome results will be published in peer-reviewed veterinary journals. To view the preliminary data summary or other clinical resources, visit our clinical information page.
What makes PetCure Oncology’s delivery of radiation therapy different than other locations?
PetCure Oncology’s clinical teams are built around seven board-certified radiation oncologists, the largest and most experienced team of its kind in the world. Every SRS/SRT treatment is planned by one – and reviewed by another – using specialized software for plan review and verification. It is then delivered by licensed radiation therapists based on protocols and standards developed by the radiation oncology team in conjunction with the Scientific Advisory Board. This level of attention and diligence, combined with rigorous quality assurance protocols at each treatment center, reflect the highest standards of radiation therapy delivery in veterinary medicine.
Treatment centers are equipped with state-of-the-art machines, usually in the form of Varian-made linear accelerators such as the Halcyon or Trilogy. These machines feature RapidArc technology and on-board imaging, two components that set PetCure apart from most other veterinary radiation therapy providers. The on-board imaging leads to improved tumor localization and increased precision, while the RapidArc delivery minimizes the toxicity to healthy tissue and shortens the duration of treatment sessions.
How can I explain SRS/SRT as a treatment option to my clients in a manner they will understand?
Advanced radiation therapy is complicated, and SRS/SRT is a new treatment option that most people are not familiar with. Many are less interested in what it is and more interested in what it can do for their pet. The important thing to convey is that SRS/SRT maximizes the dose of radiation to the tumor while minimizing the risk to normal tissues and minimizing the risk of anesthesia. In certain cases, it can be delivered with the intent to cure.
SRS/SRT is simply one choice among cancer treatment options. It is not always the answer. Our commitment is to support you in presenting your clients with all of the options as you help guide them through the process of identifying what is best for their pet and their family. There are no guarantees in cancer treatment, but in the right situation, SRS/SRT can be an effective and efficient alternative to traditional radiation therapy, chemotherapy or surgery.
What if SRS/SRT is not the right treatment option for my patient?
Our goal is to support you in providing the best possible care to your patients, and that includes making sure we find the most appropriate treatment option for each individual case. While we believe that those options need to include SRS/SRT for a client to make a fully informed decision, PetCure Oncology recognizes that every case is different and should be treated accordingly based on the best interests of the pet and their family. If you are not sure whether SRS/SRT is appropriate for a particular patient, we encourage you to contact us at 833-PET-HERO so one of our Pet Advocates can connect you with a clinician.
I am a veterinary specialist. How involved will I be following a referral?
Our intention is not to take control of your patient, but to offer a collaborative approach that is in the best interest of the pet and their family. If you are a veterinary specialist, we hope you view PetCure Oncology as a tertiary referral option that acts as an extension of your practice. If you have a client that can benefit from SRS/SRT, we will make sure you have access to the best possible care pathways. During treatment, collaboration and transparency will be paramount. Our team will be in direct contact with you and update you as requested. Upon completion of the treatment, the case will be returned to your practice for ongoing care.
What should I expect following treatment?
In most cases, follow-up visits should be scheduled at two weeks and three months (for a CT) to monitor recovery. These visits are typically conducted by the referring veterinarian, but we are happy to perform the follow-up visits if requested and are always available to help with questions or concerns that may arise after treatment. We don’t want to interfere with your doctor-patient relationship but still want to be responsive to any questions or problems that may arise.
Since the case will typically be returned to you following the referred treatment, clients should be advised to contact you directly with any questions that may come up during the recovery process. Acute post-treatment symptoms are typically minimal and can usually be addressed within your practice. At all times, PetCure Oncology will remain available to you for consultation and collaboration.
Who should I contact if I have questions about a case or want to refer a patient?
Why is PetCure Oncology creating a national network of SRS/SRT centers?
An estimated 12 million cases of cancer are diagnosed in dogs and cats each year, yet when PetCure Oncology was founded, there were fewer than 70 traditional veterinary radiation therapy facilities in the U.S. Of those, less than 10 were providing SRS/SRT. This is a significant unmet need that PetCure Oncology is committed to filling.