Clinical Study: Time to Maximal Response to Neoadjuvant Corticosteroids in Dogs with Mast Cell Tumors

Purpose of Study:

Mast cell tumors (MCT) are the most common skin tumor in dogs. MCTs can be treated in a variety of ways, with surgery being a common component of care. When MCTs are located in a challenging surgical location, we will try pre-treating with drugs to shrink the tumor and give the surgeon more flexibility. Historically, these pre-surgical treatments include chemotherapy and/or corticosteroids. Anecdotally, if the MCT shrinks, the effect only lasts for a limited period. To date, there are no studies identifying the ideal time between starting steroids and performing surgery. In this study, we plan to identify canine patients with cutaneous MCTs, administer corticosteroids, and before proceeding to surgery, clients (pet owners) will obtain daily measurements.

The aim of this study is to identify guidelines for pre-operative steroid treatment with secondary goals of decreasing surgical risks and improving post-operative outcomes in dogs affected by this disease. Identifying an ideal pre-surgical treatment window can improve veterinarian confidence in surgical scheduling, help facilitate successful surgery, and limit the influence of steroids on wound healing.

Eligibility Criteria:

• Inclusion criteria:
  • Confirmed mast cell tumor diagnosis via cytology or histopathology (may be completed through primary veterinarian or at MSU)
  • Cutaneous mast cell tumor located on the trunk (above the elbow or knee)
  • Mast cell tumor measures between 2-6cm in one dimension
  • Bloodwork confirming adequate organ function and ability to undergo general anesthesia (may be completed through primary veterinarian or at MSU)
• Exclusion criteria:
  • Prior anti-cancer treatment, including steroids, within 7 days
  • Patients on NSAIDs need 5 or more days of washout before enrolling
  • Evidence of MCT metastasis
  • Expected survival < 4 weeks with treatment
  • Diabetes mellitus or other systemic condition that interferes with safe steroid administration

Eligibility Diagnostics:

Prior to study entry, pet owners will be responsible for an initial consultation at MSU and to complete the following diagnostics for their dog:

• Cytology or histopathology of tumor in question to confirm diagnosis of MCT (if not already completed)
• Bloodwork ensuring adequate organ function to undergo general anesthesia (if not already completed)

Staging diagnostics including abdominal ultrasound with cytologic evaluation of regional lymph nodes, spleen, and/or liver will be contingent on a overseeing clinician’s recommendation as well as client election. This is not a requirement for inclusion.

Treatment:

Initial caliper measurements of the tumor will be obtained by 2 trained staff members on the day of enrollment. Clients will be trained by MSU staff in caliper usage and each dog will be prescribed prednisone, diphenhydramine, and either famotidine or omeprazole for 14 days.

Each morning, the clients will obtain caliper measurements of the MCT in the 3 planes as instructed per specific training images. Photographs that include the caliper will be emailed to the primary investigators daily. In-person evaluations will be completed at MSU on days 7 and 14 to confirm measurement accuracy and allow for surgical planning.

Surgical resection will be planned for Day 14 (+/- 1 day) with the MSU Soft Tissue Surgery service, and tissue will be submitted for biopsy analysis. Patients who experience significant or rapid tumor shrinkage may undergo surgery sooner.

If at any time throughout treatment, the tumor grows by >20%, the patient will be removed from the trial and given appropriate care based on clinician discretion.

Compensation:

• This is a partially funded trial
  • Up to 50% of the surgical fees and the histopathology fees will be covered
  • All trial-specific medications (prednisone, diphenhydramine, famotidine/omeprazole) will be covered once enrolled
  • Calipers will be provided
• If additional surgery is completed under the same anesthetic event, the client will be financially responsible

Contact Information:

Please feel free to contact our Medical Oncology Team at (517) 353-5420 or cvm.oncoinfo@msu.edu to refer a patient or for any additional information. Referring veterinarian and client calls are welcome.