James P. Farese,     Rohnert Park, California

Tumor Excision

One fundamental of oncologic surgery is an understanding of the classification scheme that describes different types of tumor excision. This nomenclature, published by Enneking (1983), is an important means of communication between oncologists. It also helps the surgical oncologist categorize levels of tumor excision and have a clear goal for the amount of tissue that must be excised in the context of the overall treatment plan (e.g., when the combination of surgery and radiation therapy [RT] is being considered).

Understanding Tumor Biology

All tumors are not created equal, and even within the benign and malignant categories tumor behavior varies. The surgeon must be familiar with the biologic behavior of the individual tumor types because tumor identity affects many aspects of case management. In general, carcinomas metastasize via the lymphatic system, and sarcomas via the hematogenous route. However, the two vascular systems are connected by lymphovenous communications, and there are exceptions to these patterns. A strong knowledge base enables the surgeon to perform thorough physical examinations and educate the client about tumor behavior (e.g., degree of local invasion, patterns of metastasis), important staging tests, the type of resection required for cure, and long-term prognosis. Perhaps the best example of the importance of understanding tumor behavior is illustrated by the behavior of appendicular osteosarcoma. In these cases the client must understand that, despite “clean” chest radiographs, dormant micrometastasis in the lungs likely is present and that the possibility of cure is extremely low. Understanding tumor behavior helps guide these preoperative staging evaluations.

Client Communication

The surgeon must develop a good relationship with the client and communicate effectively. Owners of pets with cancer often are anxious and overwhelmed about the condition of their pets, which makes effective communication challenging. Given the aggressive nature of some surgical resections (e.g., nasal planum resection), surgeons should prepare clients for the expected postoperative appearance of their pets. To do this, clinicians can create an image library depicting immediate postoperative and follow-up appearance from other cases. Clients must have a good understanding about the patterns of the disease, the likelihood of local recurrence, and the overall prognosis.

Almost as important as knowing when to recommend surgery is knowing when the disease state is too advanced to warrant surgery or will cause the patient to have a poor quality of life because of the extent of the resection. For example, resection of a large thyroid carcinoma that is fixed and invading underlying tissues likely would be incomplete and associated with significant hemorrhage and high morbidity. Furthermore, this surgery likely would not be curative because of local tumor thrombi and/or metastatic disease. The value of this determination cannot be overemphasized, and the ability to communicate this effectively to clients is crucial. Reactions from clients vary greatly regarding their view of acceptable surgical procedures. Some clients may be comfortable with radical laryngectomy and a permanent tracheostomy for a laryngeal neoplasm; others will not consider limb amputation because they cannot bear the thought of seeing their pet with such an altered appearance. Clients who initially are reluctant to have a certain procedure performed often change their minds once they have had a chance to reconsider the information or speak with another client whose pet was treated similarly. However, the surgeon must not impose a decision on clients who are undecided about surgery and make sure the client is comfortable with the plan. Many veterinary cancer centers use mental health professionals to assist with the surgeon-client communication and provide support to clients during the decision-making and/or treatment process.