Lecture on Soft Tissue Sarcoma in Dogs

Introduction

• Discussion on treatment options for soft tissue sarcomas in dogs.
• Case example: Sarcoma on the right front leg of a dog.
• Consideration of primary tumor and risk of secondary metastasis.

Tumor Grading and Metastasis

• Tumors are graded 1, 2, and 3:
  • Grade 1: 5-10% chance of secondary spread.
  • Grade 2: ~10% chance of secondary spread.
  • Grade 3: ~50% chance of secondary spread.
• Chemotherapy is generally ineffective in preventing secondary spread.

Tumor Location Impact

• Tumors on extremities are less aggressive than those on the trunk.
• Past studies show extremity tumors rarely metastasize.
• Importance of chest radiographs to assess metastasis or other tumors.

Treatment of Primary Tumor

• Surgery: Primary treatment option.
  • Check for surgical margins:
    • Clear margins: Predictive of no recurrence (5% risk of recurrence in 5 years).
    • Dirty margins: 75% chance of recurrence in 5 years.

Post-Surgical Options for Dirty Margins

• Additional Surgery: Most effective for achieving clear margins.
• Wait-and-See Approach: Viable for older dogs with low/intermediate-grade tumors on extremities.
• Radiation Therapy: Reduces recurrence from 75% to 20% in 5 years.
• Metronomic Chemotherapy: Applied every other day, reduces recurrence rate similarly to radiation therapy.

Case Considerations

• High-grade tumors warrant thorough staging (e.g., chest x-rays).
• Importance of checking post-surgical margins for predicting recurrence likelihood.

Surgical Oncology Principles

1. Biopsy the Tumor: Determine the type and behavior of the tumor.
2. Literature Review: Understand tumor behavior and potential for surgical cure.
3. Staging: Conduct thoracic radiographs and possibly lymph node aspiration.
4. Curative Intent Surgery: Aim to cure, with adjuvant therapy as backup.
   • Options include radiation therapy and metronomic chemotherapy.

Conclusion

• Majority of soft tissue sarcomas can be cured with appropriate treatment.
• Adherence to surgical oncology principles is crucial for effective treatment.
• Importance of clear surgical margins and understanding tumor behavior for patient outcomes.

Final Notes

• Follow tenants of surgical oncology to prevent oversight in patient care.
• Open invitation for questions and comments post-lecture.