Fundamentals of Surgical Oncology in Small Animals

 T-9

Cancer is one of the major cause of death in both humans and in animals being small, large or wild animal, surgical removal of tumors is one of the most common procedure carried out by the veterinarians. This blog covers tumor evaluation, biopsy, grading and staging, along with surgical procedure. 

In Veterinary Medicine, Surgery is considered the most important component of treating canine and feline suffering from solid tumors, because in many cases surgical procedure is the best option which offers the best chance of improving patient’s quality life. 

The basic principle of Surgical Oncology includes the following – 

• Characteristic of Tumor being treated
• Available Surgical Options 
• Potential needs for adjunctive treatments along with the primary treatment such as Chemotherapy or Radiation therapy.

Therapeutic treatment is also provided to improve the patient’s quality of life.
Patient Evaluation Before considering surgical option you should have a complete patient medical history. On the basis of history a suitable surgical plan must be designed on the basis of Physical Examination, Diagnostic Imaging, Clinical Cyto-Pathology and Histopathology. A plan must be implemented afterward with a complete analysis of lab-reports. Tumor Identification  Physical Examination plays an important role in identification of neoplasia, either via palpitation or paraneoplastic syndromes, which maybe found on a routine blood and urine analysis. It allows detection of possible tumor presence and identification of underlying conditions that may influence the treatment plan.After tumor is identified, record it’s location, size, gross appearance and palpate lymph nodes. Lymph Biopsy is also recommended in some cases, normal lymph node palpitation doesn’t guarantee lack of metastasis.     
Tumor Evaluation is done by Histopathologic Analysis of tissue is obtained during Biopsy, which allows the definitive diagnosis of :- 

• Tumor Type (Hyperplasia, Metaplasia, Neoplasia)
• Tumor Grade
• Biological behavior (Malignant or Benign)
• Aggressiveness    

There are 4 types of tumor biopsy techniques: 

1. Needle-core Biopsy– it mainly includes 2 techniques, Tru-cut needle-core for Soft tissues and Jamshidi needle-core for Ossified tissues. 
2. Fine-needle Aspiration (FNA)- a cost effective, minimum invasive procedure useful for differentiation of neo and non-neoplastic diseases.  
3. Incisional Biopsy– is utilized when less invasive techniques fail to yield a diagnosis especially for soft, friable, necrotic, inflamed tumors. 
4. Excisional Biopsy– allows the identified tumor to be removed in its entirety, with or without surgical margins.  It is a common approach for mass removal in veterinary medicine yet controversial. 

Biopsy Procedure must be carefully planned to prevent the spread of necrotic cells to unaffected tissue and allow to remove of biopsy tracks or scars during excision of the tumor. Coagulation Testing should be carried out when obtaining the biopsy of vascular organs such as liver, spleen. Biopsy Procedure is mainly considered when the  

• Surgical Plan will be affected by tumor characteristics 
•  Owner’s willingness to treat may be altered based on diagnosis.

Tumor Grading & StagingGrading is the histopathologic assessment of the tumor’s aggressiveness, mitotic index, degree of differentiation and invasiveness to nearby tissues. Staging establishes to what extent the tumor has invaded local, regional or systemic tissue. It is done when the suspected tumor is malignant.

Surgical Intervention & Planning There are 4 levels of surgical aggressiveness, or surgical dose, to classify the extent of surgical resection. The most common mistake is the use of surgical dose, that is too low, which results from concerns about the ability to close the resultant defects. However, if the diagnosis of malignancy has been confirmed, it’s maybe better to manage an open wound than leave tumor cells behind. Surgical Planning – careful surgical planning should be done, as the first surgery is often the surgeon’s best chance for achieving a positive outcome. Multiple factors should be considered when determining aggressiveness of surgery- tumor type, short and long term prognosis, concurrent diseases, owners wish,  availability of adjunctive treatment.  Surgical Margins width must be known and careful tumor handling is required to prevent exfoliation of cells and local recurrence. Avoid direct handling of the tumor and change the surgical gloves and instruments between tumor excision and closure. 

Surgical Closure  Is the final step of surgical intervention, which can be completed by two closure types – Primary closure the skin is closed at the end of the surgery, whereas in Secondary Closure the wound is left open at the end of the surgery and heals by granulation and contraction. 
Tissue Analysis and Dirty Margins Resected tissue should be prepared for analysis to determine the extent of tumor resection. Despite Biopsy, following resection occasionally reveals that tumor was inadequately resected. Dirty Margins provide information about where the neoplasm extends beyond the surgical margins (normal tissue).

     “Right now, after having had back surgery, I am finally back to running again”
                                    

  THE GEEK VETERINARIAN