Stereotactic ablative radiotherapy (SABR) for lun metastases

This study will evaluate whether a single, highly focused dose of radiation can safely treat cancer that has spread to the lungs in dogs. Our radiation treatment is administered externally by delivering high-energy x-rays directly to the tumor so there is no risk of radiation exposure for people in contact with pets receiving this type of therapy. We will assess how practical the treatment is, including treatment planning, managing breathing during radiation for prolonged periods of time, radiation delivery, and the time dogs need to be under anesthesia. The study will also monitor dogs for short- and long-term side effects and evaluate how well the treated tumors respond. Investigators will track how long the treated tumors remain under control and how long the dogs remain free from further cancer progression. The goal is to determine whether this single radiation treatment can safely and effectively control cancerous spread to the lungs.

Inclusion Criteria

Dogs are eligible for enrollment if they meet all of the following criteria:

• Confirmed malignancy: Cytologic or histopathologic confirmation of a malignant tumor (e.g., carcinoma, sarcoma, or melanoma) with pulmonary nodules consistent with metastasis to the lungs.
• Limited and progressive pulmonary metastases: Presence of 2–10 pulmonary nodules consistent with oligometastatic disease. Disease progression must be documented on thoracic radiographs or CT (Computed Tomography) imaging over at least 6–8 weeks, defined as either a ≥20% increase in lesion size or the development of new pulmonary lesions, according to VCOG v1.0 criteria.
• Control of primary and other metastatic disease: The primary tumor and any confirmed regional lymph node metastases must have been adequately controlled with definitive-intent surgery and/or radiation therapy. Any confirmed metastatic disease outside the lungs must also be adequately controlled with appropriate local and/or systemic therapy.
• Expected survival: An estimated survival time of at least 3 months, as determined by the attending veterinary oncologist.
• Recent thoracic imaging: Three-view thoracic radiographs, accompanied by a radiology report, obtained within 1 month before enrollment.
• SABR candidacy and technical feasibility: The attending veterinary radiation oncologist must determine that the dog is an appropriate candidate for stereotactic ablative radiation therapy (SABR). The radiation oncologist must determine that all progressive pulmonary lesions measuring ≥5 mm can be safely and technically treated, while meeting the study-defined lung dose constraint.
• Adequate overall health: Acceptable clinical status, including an ECOG (Eastern Cooperative Oncology Group) performance status <2, adequate blood cell counts and organ function, and the ability to safely undergo general anesthesia. A complete blood count and serum biochemistry panel must be obtained within 30 days before anesthesia.
• Owner consent: Written informed owner consent must be obtained before enrollment.

Regarding systemic therapy:

• Prior systemic therapy (of any type) is permitted.
• Concurrent systemic therapy (including cytotoxic chemotherapy, immunotherapy, or molecularly targeted agents) is permitted during the 3-month study period, provided it has been initiated at least 6–8 weeks prior to the start of SABR and includes at least two radiographic assessment time points to evaluate response of target lung lesions.
• Cytotoxic chemotherapy must be discontinued at least 2 weeks prior to SABR and may be resumed 2 weeks following treatment.
• Molecularly targeted agents and immunotherapies may be continued during SABR, provided they are clinically well tolerated by the patient, if deemed acceptable by attending radiation oncologist.

Exclusion Criteria

Dogs will not be enrolled if any of the following are present:

• Presence of a malignant pleural effusion (cancer-associated fluid accumulation around the lungs).
• Significant abnormalities in overall health that would make anesthesia or radiation therapy unsafe.
• Failure to meet the minimum required laboratory or clinical criteria for safe treatment.
• Previous enrollment in this study. A second course of radiation therapy for pulmonary metastases will not be provided under this study.

Client Benefits

Owners are responsible for the costs of pre-enrollment bloodwork, chest X-rays, CT imaging required for radiation treatment planning, and confirmation of the tumor diagnosis. The study will cover all costs associated with the radiation treatment and the one month follow-up examination. The study will also cover up to $860 toward the 2–3-month follow-up CT appointment. This amount is expected to cover the full cost of the visit, including the examination, bloodwork, and CT imaging under heavy sedation, provided your pet is healthy and does not require additional anesthesia services for safety reasons.

If your pet develops side effects to the lungs or other health concerns that require an earlier evaluation during the study period, the study will also cover the cost of a recheck examination, chest X-rays, and medications related to the adverse event.

Sample or Data Requirements

If your dog participates in this study, they will receive a single, highly targeted dose of radiation therapy while under general anesthesia. Before treatment, a CT scan (3D imaging technique) will be performed to develop a personalized radiation treatment plan. A follow-up examination will be performed approximately one (1) month after treatment to assess for any side effects. A final follow-up examination and CT scan, performed under heavy sedation or anesthesia, will be performed approximately 2–3 months after radiation therapy to evaluate the tumor’s response to treatment. If your pet develops coughing, difficulty breathing, or other respiratory concerns during the study period, a recheck examination and chest X-rays will be recommended.

Contact Information

For questions regarding the clinical trial, please email clinicaltrials@tufts.edu.