Principles of surgery for the cancer patient

Principles of Surgery for the Cancer Patient Sean W. Aiken, DVM, MS, Diplomate

ACVS

The appropriate diagnosis and treatment of patients with cancer are most correctly made through the cooperative efforts of a 'team of specialists, including an oncologist, surgeon, and pathologist. Preoperative determination of the tumor type and histologic grade, extent of the mass, and the patient's health status will result in the most comprehensive course of action. Diagnosis and staging of the tumor are paramount to preparing an optimal treatment plan. To ensure the best possible outcome, the preoperative, surgical, and postoperative plan should be customized to the individual cancer patient and their owner while following given guidelines. This article describes the basic principals for evaluation and operative management of the surgical oncology patient. © 2003 Elsevier Inc. All rights reserved.

he treatment of the cancer patient is a cooperative process

T between the.surgeon, oncologist, and the pathologist (or cytologist). As a practitioner, you may play the role of cytologist, oncologist, and surgeon, or you may choose to refer the case to a specialist at some point in the treatment process. Whichever the case, the successful treatment of the cancer patient is dependent on consultation and planning among this muhidisciplinary treatment team. Surgery will play a role in the treatment plan for most cancer patients. The surgical oncologist must know the anatomy and physiology of the surgery patient, be proficient in reconstructive surgery techniques, and understand the extent of and the expected behavior of the tumor (tumor biology) to achieve the best possible outcome. The goals of surgery in the cancer patient usually consist of one or more of the following: biopsy diagnosis, palliation of symptoms, cytoreduction as an adjuvant for other treatment modalities, or resection with intention to cure.1 The surgical goals should be well defined in advance of the procedure.

Diagnosis and Staging Preoperative diagnosis of tumor type and histologic grade, extent of the mass, and evidence of spread (metastasis) of a mass is paramount in allowing the surgical oncologist to make appropriate decisions about the definitive treatment plan. Without this knowledge, an informed decision cannot be made concerning the extent of surgery needed, the possible need for additional therapies (radiation, chemotherapy), or the prognosis. 2 The pet owner will need this information to make an informed decision on treatment, balancing the extent of the surgical procedure with the prognosis while evaluating the From the Animal Medical Center, New York, NY. Address reprint requests to Sean W. Aiken, The Animal Medical Center, 510 East 62nd Street, New York, NY 10021. © 2003 Elsevier Inc. All rights reserved. 1096-2867/03/1802-0003530.00/0 doi:l 0.1053/svms.2003.36619

financial factors involved. Exceptions to presurgical biopsy include those cases that are surgical emergencies (ruptured splenic or intestinal masses), in which the knowledge of the tumor type will not change the surgical procedure (solitary lung, splenic, or intestinal masses) or when the risks of preoperative surgical biopsy are higher than the definitive surgical procedure (brain or spinal cord masses).3 Before any surgical procedure, all cancer patients should have a complete physical examination that will define the extent of the mass, reveal any evidence of metastasis, or identify any concurrent lesions. A complete blood count, serum chemistry panel, and urinalysis should be performed to assess the general health of the patient, and identify coexisting medical conditions or paraneoplastic syndromes 4 that may alter the surgical or anesthetic plan. Abnormalities in the blood tests may also alter the prognosis (eg, negative prognostic indicator of elevated serum alkaline phosphatase in dogs with osteosarcoma) 5-r or chemotherapy treatment protocols. Cytological examination (fine needle aspirate) is often the initial step in the diagnostic process of the primary mass. Cytology can offer a simple, inexpensive, and rapid way of differentiating between an inflammatory, benign, or malignant mass. With regard to neoplasia, the cytological diagnosis is often limited to broad categories such as round cell, epithelial, or spindle-cell tumor, but a few tumor types can be definitively diagnosed with cytology alone, s A fine needle aspirate is best performed with a 21- to 25-gauge needle inserted into the mass, aspirating, partially withdrawing and then redirecting the needle, and repeating this process several times. The contents of the needle are then ejected onto a microscope slide using a syringe. 9 If the cytology specimen is nondiagnostic, or the clinical behavior of the mass does not correlate with the cytological diagnosis, then a tissue biopsy should be performed. A definitive diagnosis of a mass often requires histologic evaluation of a tissue sample. Histopathology may also provide a histologic grade to help determine prognosis and guide further therapy. There are many techniques in obtaining tissue samples for histologic evaluation, but the goal should be to provide the pathologist with a representative sample of the mass. Many of these techniques are dependent on tissue type, site, and surgeon preference, and have been previously reviewed. 3 When performing any of the surgical biopsy techniques, great care should be taken not to disrupt the normal anatomic architecture or contaminate adjacent normal tissues. Careful tissue handling and meticulous hemostasis is required to prevent a hematoma or seroma from forming, the result of which could allow neoplastic cells to dissect along normal tissue planes. The biopsy should be planned such that the biopsy site and the entire biopsy tract can be removed during the definitive surgical procedure. Diagnostic imaging techniques such as radiographs, computed tomography, or magnetic resonance imaging may be helpful in selecting the biopsy site by understanding the extent of the lesion, the possible origin of the

Clinical Techniques in Small Animal Practice, Vol 18, No 2 (May), 2003: pp 75-81

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Fig 1. A contrast-enhanced computed tomography scan of a dog with a relatively small palpable external body wall mass ultimately revealing the extensive nature of the mass. The computed tomography scan also suggests that the center of the mass is either necrotic or a hematoma and that the mass most likely originates from the transverse spinous process.

mass, and the location of any major neurovascular structures. 3 (Fig 1) Incisional biopsies should be oriented in the direction of the definitive surgical resection. Ideally, the surgical biopsy should be as large as possible and be located at the margin of the mass and the normal adjacent tissue. If a needle-biopsy technique is used, then multiple specimens from different locations in the mass should be taken to represent the entire mass lesion. 1°,1* If biopsies of multiple unassociated masses are to be performed, then each biopsy should be obtained with separate instruments and gloves, and submitted to the pathologist in separate containers. Biopsies of bone lesions may be obtained either with an open technique, trephine, or with a Jamshidi bone marrow needle. 5,~2 The advantage of the Jamshidi needle is the relative ease of use, decreased incidence of pathologic fractures, and decreased chance of hematoma formation when used in a closed technique. 12 A Jamshidi needle biopsy is performed by taking multiple samples through the same entry site at various angles, of the middle of the bony lesion and up to the opposite cortex (Fig 2). The biopsy site may be documented with radiographs or fluoroscopy to ensure accurate biopsy location (Fig 3). As with cytology, if the tissue diagnosis does not correlate with the clinical behavior of the tumor, then the histologic diagnosis must be questioned. Contacting the pathologist and giving additional information, 13 providing additional tissue, or requesting special stains or a second pathologist's opinion may be required.14 Staging of tumors is required to devise an appropriate treatment plan, to provide an accurate prognosis, and to be able to compare treatment response among individuals. 15 The World Health Organization characterizes disease involvement into local disease or tumor (T), regional lymph node involvement (N), and distant site involvement or metastasis (M). Subscripts 0, 1, 2, and 3 are used to define the disease in each category (Table 1). x6 When staging a patient, the goal is to define the boundary of the mass and to determine if there is any evidence of meta76

static disease. Although controversial, ~r,18 three radiographic views (right and left lateral and ventrodorsal projections) of the thoracic cavity are routinely obtained for evaluation of pulmonary metastasis. Abdominal ultrasound is used to screen the abdominal cavity for primary, metastatic, and concurrent disease. Local lymph nodes should be screened with fine needle aspirations even if there is no palpable enlargement to rule out local tumor spread. Enlarged local lymph nodes may simply be reactive, or palpably normal nodes may contain metastatic lesions, t9 Screening tests such as lateral limb radiographic surveys and nuclear scintigraphy may be indicated when evaluating patients with primary bone tumors or tumors that metastasize to bone. a°-= The local tumor should be evaluated for the size and degree of invasion to local tissues by palpation. If the extent of the entire mass cannot be palpated or the mass is fixed to underlying tissue, then additional evaluation with local radiographs, computed tomography, magnetic resonance imagining, or ultrasound is indicated. Specialty procedures such as thoracoscopy or laparoscopy may be used to determine the organs involved or the extent of spread within the thoracic and abdominal cavities.

Surgical Resection Tumor resection margins are based on the information gained during diagnosis and staging. Preoperative planning of margins is dictated by the tumor's anticipated biologic behavior based on the tumor type and histologic grade or cellular characteristics. As a rule, any tissue that the tumor contacts or invades must be removed with enough of a margin of normal tissue to remove all microscopic neoplastic tissue, t4 For tumors with a high rate of recurrence, such as soft-tissue sarcomas and high grade mast cell tumors, a 2- to 3-cm margin should be planned. 1,23,24 The deep margins should usually be planned for at least one tissue plane beyond the mass. The anatomic site will SEAN W. AIKEN

Fig 2. Illustration of the use of a Jamshidi bone marrow needle to obtain a biopsy specimen from a distal radial bone lesion. Multiple biopsy samples should be obtained from the lesion at different angles (A, B, and C) through the original penetration site in the bone.

also dictate the extent of the resection, as some anatomical sites provide the flexibility to achieve wide margins with ease and other sites make margins difficult or impossible without compromise to the patient. Planning surgical margins also involves planning the closure, but a difficult closure or compromise of adjacent normal structures should not compromise the surgical excision if the ultimate prognosis after complete resection is good (Fig 4). The initial surgical excision has the highest likelihood of a successful outcome and should be thought of and planned as the final procedure. Simply removing the mass with the intention of a second surgery, if it were to recur, significantly decreases the chance of a successful outcome by altering the surgical anatomy, requiring larger surgical resections, and allowing more time for the tumor to metastasize. Marginal resections (removal of the mass just outside of the pseudocapsule) should be confined to benign lipomas. Radical resections are not always indicated, and just because a radical surgical procedure is technically possible, it does not always improve the outcome, and therefore may not be indicated (radical masPRINCIPLES OF SURGERY FOR THE CANCER PATIENT

tectomy for mammary adenocarcinoma in dogs, total cystectomy in dogs with transitional cell carcinoma, etc.), s Gentle tissue handling should be employed throughout the surgical procedure to minimize the chance of dissemination of tumor cells. Surgical margins should be respected throughout the resection and at no time should the tumor capsule be penetrated. All biopsy tracts should be excised and any scars from previous surgical resections should have the same surgical margins as the primary mass. After surgical excision, the wound bed should be copiously lavaged to remove any blood or any exfoliated tumor cells that may have been released into the wound. After the surgical excision is complete, gloves and contaminated surgical drapes should be changed and separate surgical instruments should be used for wound closure and or reconstruction (if an additional mass or lymph node is to be excised, an additional separate set of gloves, instruments, and drapes should be used for the procedure). Before closure of the wound bed, margins should be marked for future reference pending the possibility that re-excision is required, as a location 77

Fig 3. A fluoroscopic image of the use of a Jamshidi bone marrow biopsy needle to obtain a biopsy specimen from a proximal humeral bone lesion, Fluoroscopy may be used to confirm the location of the biopsy site and bone lesion,

marker for postoperative radiation therapy, or to monitor the local tissue bed for recurrence. Stainless-steel hemostatic clips or stainless-steel suture material may he used and identified on future radiographic studies. Stainless steel will result in signal interference i n magnetic resonance imaging and computed tomography imaging. If subsequent magnetic resonance imaging or computed tomography imaging is expected, then titanium hemostatic clips should be considered. Cancer patients are often considered at a higher risk for surgical wound infections. A diagnosis of cancer is not solely a risk factor for infection, but given these are usually elderly patients that are often treated with adjuvant chemotherapy or radiation therapy, prophylactic antibiotics should be considered during surgical procedures. 25 Cephazolin (20 mg/kg) given intravenously at the time of induction and every 2 hours until the time of wound closure is generally considered the

TABLE 1, TMN Classification for Tumors in Animals(16) Primary Tumor (T) TO T1 T2 T3 Node (N) NO N1 N2 N3 Metastasis (M) M0 M1 M2

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No evidence of neoplasia Tumor <1 cm diameter, non-invasive Tumor 1-3 cm, locally invasive Tumor > 3 cm, locally invasive, ulcerated No evidence of nodal involvement First station node involved, firm enlarged, not fixed First station node involved, firm, fixed Nodal involvement beyond the first station No evidence of metastasis Distant metastasis to one organ Distant metastasis to more than one organ

prophylactic antibiotic of choice. Prophylactic antibiotics should not be continued longer than 24 hours after surgery. 2~

Surgical Margins The surgical margins of the excised mass should be evaluated for completeness of the excision. The entire mass should be submitted for histopathologic evaluation. Margins of interest should be marked for identification by the pathologist, because the mass usually becomes distorted during the fixation process. The margins of the mass can be marked with a variety of materials, such as India ink or specialty surgical marking inks. India ink can be obtained from most art-supply stores and surgical marking inks are available from surgical supply houses in many colors (yellow is a favorite among the pathologist at our institution). The variety of colors allows differential marking of the various margins (deep vs. lateral). (Fig 5) The margins of the mass are painted with the desired marking agent and allowed to dry for a few minutes before placing the mass in formalin. An alternative to applying ink to the surgical margins is to provide margins separately from the mass. After the mass is excised, additional tissue is removed from the wound bed and submitted in separate labeled containers. If the resection involves or contains bone, radiographs of the excised bone should be taken to help assess the completeness of the resection (Fig 6).2r

Wound Closure and Reconstruction A variety of techniques are available to reconstruct and close the wound bed. Axial pattern and local skin flaps, skin graft, and skin-advancing techniques have been described and reSEAN W. AIKEN

Fig 4. (A) Resection plan of a nerve-sheath tumor dorsal to the orbital rim. The resection margins include 2 cm lateral to the site of tumor recurrence and the previous surgical scar. The planned resection includes the eye and orbit to achieve 2-cm margins. (B) Surgical specimen after excision and labeling of the edges of the resection with tissue dye to assess for histologic margins.

viewed. 2s-3° During wound closure and reconstruction, great care should be taken to disrupt as little unaffected tissue as possible. If the surgical margins are incomplete (tumor at the margin of resection), then any additional disrupted tissue planes at the surgery site will be considered contaminated. For the same reason, areas disrupted by elevating skin flaps or from placement of surgical drains will need to be considered part of the postoperative radiation field. For this reason, local tissue

PRINCIPLES OF SURGERY FOR THE CANCER PATIENT

should be disrupted as little as possible and local tissue advancement should be considered before elevation of axial pattern or distant flaps. If the surgical margins are in question, then open wound management can be used until final pathology results are available. Great attention to hemostasis and surgical wound drainage should be made to prevent the formation of seromas and hematomas that can dissect and further disrupt tissue planes.

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Fig 5. The surgical specimen after excision of a fibrosarcoma arising from the digit. The lateral surgical margins are marked with yellow tissue-marking dye (Shandon, Pittsburgh, PA) to differentiate them from the ventral margins, marked with India ink, during the histologic evaluation of the margins of the resection.

Fig 6. (A) A lateral radiographic projection of a dog with a primary osteosarcoma lesion in the distal ulna. (B) A specimen radiographs of the excised ulna to evaluate the completeness of the excision before wound closure. If inadequate margins are noted on the specimen radiograph, then additional bone may be removed to achieve a complete excision. 80

SEAN W. AIKEN

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