Surgery is the oldest modality of treating cancer and more patients are cured by surgery alone than by any other mean of cancer treatment. Nowadays, thanks to adjuvant therapy, aggressive treatments resulting in mutilations and amputations can be avoided leading, nevertheless, to better results. Some ethical aspects should be remembered and previous authors should be quoted:
Aegypt (3000 BC) 'Surgeon should contend with tumors that might be cured by surgery'.
Hippocrates (450 BC) 'Surgeon should avoid treating terminal patients whose quality of life would be better without surgery'.
Oncologic surgery embraces many aspects: biopsies, surgical excision, cytoreduction/palliative surgery, prophylactic surgery, emergencies, supportive surgeries and treatment of metastasis. Here, the author will concentrate on the most common indication for oncologic surgery, i.e., tumor removal and will analyse the key for successful surgeries.
Before operating a tumor, any of us should be able to answer these questions:
Do I know enough about this tumor?
Do I know how to treat it?
Can I operate on it adequately?
The pre-operative work-up should include an evaluation of the patient as well as the tumor. If the tumor can be palpated, this could give some information but it should not be manipulated to avoid tumor cells from spreading. Specific imaging techniques are often necessary to provide information about local invasiveness. Cytological and histological diagnosis is mandatory before any further recommendation can be made either medical or surgical. Local and focal lymph nodes, as well as any possibility of distant metastates, should be evaluated. The newest diagnostic modalities are necessary in order to minimize the risk of operating patients with severe metastatic disease. Thanks to ultrasound or CT, any suspicious tissue, even distant from the primary tumor itself, can be aspirated.
When cytological examination is not reliable, or when more information is needed, tissue biopsies should be performed. Specific guidelines for biopsies have been edicted:
Choose the right sites at the junction between pathologic and healthy tissue
Choose multiple directions
Avoid necrotic centers
Avoid crossing healthy tissue
Use mini-invasive surgery for abdominal biopsies when fine-needle aspirates give negative results
Once enough information has been collected from the patient and its tumor (staging and grading), the veterinarian should wonder if he knows how to treat it. In this regard, the most current literature should be consulted in up-to-date textbooks. It is usually pretty sad when owners know more from the internet than the practitioner himself. Once the need for surgery has been confirmed, the next question is: 'Can I operate on it adequately?'
The pre-operative preparation includes that of the patient and of the surgeon, i.e., preoperative planning. Many of the cancer patients suffer from poor nutritional status, mild to severe pain as well as an altered physical status. These findings should be evaluated and compensated before surgery. If necessary, a feeding tube should be placed in order to restore an appropriate nutritional status before and after surgery. Paraneoplastic syndromes should also be corrected. As a surgeon, the veterinarian should then plan tumor removal and reconstruction. Should closure difficulties be anticipated, the patient should be referred to an oncologic surgeon.
From the preparation room to the post-operative bandage, the surgeon should aim at preventing tumor cells from seeding. Aggressive surgical scrubbing of the surgical site should be avoided and adequate excision has to be chosen. Subtotal excision is basically intra-tumoral: it carries no indication except if the tumor is radiosensitive, chemosensitive or if only palliative removal is attempted.
In a local excision (intra-capsular), millions of fresh tumor cells are left in place. The capsule is nothing more than the outer limit of a tumor, where the most active tumor cells grow. Tumor cells are usually encountered in more than 50% of surgical adhesions.
In wide excision, a border of 2 to 3 cm of healthy tissue has to be taken away with the tumor itself and at least one healthy tissue layer not in contact with the tumor base should be removed.
In radical excision, the organ supporting the tumor is removed (e.g., amputation, mandibulectomy, hemi-pelvectomy).
What about the lymph nodes? They should be aspirated when palpable or visible (ultrasound). Any positive, abnormal or tumor-associated lymph nodes should be removed with the tumor itself.
In surgery, the oncologic surgeons should respect the following basic rules:
No dissection, en-bloc excision
Primary ligation of major tumor blood supply
Control of local bleeding
Prevention of dead space
Closure after changing instruments, gloves and drapes
Surgery is simply not worth it if samples from the tumor and tissue edges are not submitted. After surgery, the surgeon should help the pathologist and specify his or her needs: type, grade, proliferation or mitotic index, specific staining and margins.
During the post-operative period, evidence of infection and pain should be evaluated, controlled and treated. Before and after surgery the need for further adjuvant therapies should be mentioned to the owner. On receipt of the pathology results, these needs shall be further discussed. In conclusion, who is responsible for the recurrence of a tumor? The patient and its tumor...? Fate...? Ourselves... ?