Topics:

Principles of surgical oncology

Principles of surgical oncology

Surgical oncology, as its name suggests, is the specific application of surgical
principles to the oncologic setting. These principles have been derived by adapting
standard surgical approaches to the unique situations that arise when treating
cancer patients.

The surgeon is often the first specialist to see the patient with a solid malignancy,
and, in the course of therapy, he or she may be called upon to provide
diagnostic, therapeutic, palliative, and supportive care. In each of these areas,
guiding paradigms that are unique to surgical oncology are employed.

In addition, the surgical oncologist must be knowledgeable about all of the
available surgical and adjuvant therapies, both standard and experimental, for
a particular cancer. This enables the surgeon not only to explain the various
treatment options to the patient but also to perform the initial steps in diagnosis
and treatment in such a way as to facilitate and avoid interfering with future
therapeutic options.

Invasive diagnostic modalities

As the surgeon approaches the patient with a solid malignancy or abnormal
nodal disease or the rare individual with a tissue-based manifestation of a leukemia,
selection of a diagnostic approach that will have a high likelihood of a
specific, accurate diagnosis is paramount. The advent of high-quality invasive
diagnostic approaches guided by radiologic imaging modalities has limited the
open surgical approach to those situations where the disease is inaccessible, a
significant amount of tissue is required for diagnosis, or a percutaneous approach
is too dangerous (due, for example, to a bleeding diathesis, critical intervening
structures, or the potential for unacceptable complications, such as
pneumothorax).

Lymph node biopsy
The usual indication for biopsy of the lymph node is to establish the diagnosis
of lymphoma or metastatic carcinoma. Each situation should be approached in
a different manner.

Lymphoma The goal of biopsy in the patient with an abnormal lymph node
and suspected lymphoma is to make the general diagnosis and to establish
the lymphoma type and subtype. Additional analyses of the cells in the
node, its internal architecture, and the subpopulations of cells are critical for
subsequent treatment. Although advances in immunocytochemical and histochemical
analyses have been made, adequate tissue is the key element in
accurate diagnosis.

Consequently, the initial diagnosis of lymphoma should be made on a completely
excised node that has been minimally manipulated to ensure that there
is little crush damage. When primary lymphoma is suspected, the use of needle
aspiration does not consistently allow for the complete analyses described above
and can lead to incomplete or inaccurate diagnosis and treatment delays.

When recurrent lymphoma is the primary diagnosis, the analysis of specific
cell type is very important for assessing changes in the type of lymphoma and
whether a transformation has occurred. In the rare situation in which recurrent
Hodgkin's disease is suspected, a core biopsy may be adequate if the classic
Reed-Sternberg cells are identified. However, in the initial and recurrent settings,
biopsy of an intact node is often required.

Carcinoma The diagnosis of metastatic carcinoma often requires less tissue
than is needed for lymphoma. Fine-needle aspiration (FNA), core biopsy, or
subtotal removal of a single node will be adequate in this situation. For metastatic
disease, the surgeon will use a combination of factors, such as location of
the node, physical examination, and symptoms, to predict the site of primary
disease. When this information is communicated to the pathologist, the pathologic
evaluation can be focused on the most likely sites so as to obtain the
highest diagnostic yield. The use of immunocytochemical analyses can be successful
in defining the primary site, even on small amounts of tissue.

Head and neck adenopathy The head and neck region is a common site of
palpable adenopathy that poses a significant diagnostic dilemma. Nodal zones
in this area serve as the harbinger of lymphoma (particularly Hodgkin's disease)
and as sites of metastasis from the mucosal surfaces of the upper
aerodigestive tract, nasopharynx, thyroid, lungs, and, occasionally, from intraabdominal
sites, such as the stomach, liver, and pancreas.

Since treatment of these nodal metastases varies widely, and since subsequent
treatments may be jeopardized by inconveniently placed biopsy incisions, the
surgical oncologist must consider the most likely source of the disease prior to
performing the biopsy. FNA or core biopsy becomes a very valuable tool in
this situation, as the tissue sample is usually adequate for basic analysis (cytologic
or histologic), and special studies (eg, immunocytochemical analyses) can
be performed as needed.

Biopsy of a tissue-based mass
Several principles must be considered when approaching the seemingly simple
task of biopsying a tissue-based mass. As each of the biopsy methods has unique risks, yields, and costs, the initial choice can be a critical factor in the timeliness
and expense of the diagnostic process. It is crucial that the physician charged
with making the invasive diagnosis be mindful of these factors.

Mass in the aerodigestive tract In the aerodigestive tract, biopsy of a lesion
should include a representative amount of tissue taken preferably from the
periphery of the lesion, where the maximum amount of viable malignant cells
will be present. Since the treatment of in situ and invasive disease varies greatly,
the biopsy must be of adequate depth to determine penetration of the tumors.
This is particularly true for carcinomas of the oral cavity, pharynx, and larynx.

Breast mass Although previously a common procedure, an open surgical biopsy
of the breast is rarely indicated today. Palpable breast masses that are
highly suspicious (as indicated by physical findings and mammography) can
be diagnosed as malignant with close to 100% accuracy with FNA. However,
because the distinction between invasive and noninvasive disease is often required
prior to the initiation of treatment, a core biopsy, performed either under
image guidance (ultrasonography or mammography) or directly for palpable
lesions, is the method of choice.

An excellent example of the interdependence of the method of tissue diagnosis
and therapeutic options is the patient with a moderate-sized breast tumor considering
breast conservation who chooses preoperative chemotherapy for
downsizing of the breast lesion. The core biopsy method establishes the histologic
diagnosis, provides adequate tissue for analyses of hormone-receptor levels
and other risk factors, causes little or no cosmetic damage, does not perturb
sentinel node analyses, and does not require extended healing prior to the initiation
of therapy. In addition, a small radio-opaque clip can be placed in the
tumor to guide the surgical extirpation. This is important because excellent
treatment responses can make it difficult for the surgeon to localize the original
tumor site.

Mass in the trunk or extremities For soft-tissue or bony masses of the trunk
or extremities, the biopsy technique should be selected on the basis of the
planned subsequent tumor resection. The incision should be made along anatomic
lines in the trunk or along the long axis of the extremity. When a sarcoma
is suspected, FNA can establish the diagnosis of malignancy, but a core
biopsy will likely be required to determine the histologic type and plan
neoadjuvant therapy.

Preoperative evaluation

As with any surgical patient, the preoperative evaluation of the cancer patient
hinges primarily on the individual's underlying medical condition(s). Because
most new cancers occur in older patients, careful attention must be paid to
evaluation of cardiovascular risks. Adequate information can usually be obtained
from a standard history, physical examination, and electrocardiogram
(ECG), but any concerns identified should be subjected to a full
diagnostic work-up.

The evaluation should also include a detailed history of current and previous
therapies. Many patients will be on anticoagulation, aspirin, or analgesics, all
of which may impact on their perioperative management. Previous use of doxorubicin
may be associated with cardiac dysfunction and the use of bleomycin
with severe lung sensitivity to oxygen concentrations > 30%.

Prior radiation therapy is associated with fibrosis and delayed healing. An appreciation
of potential postoperative problems secondary to these factors is
important in planning the surgical extirpation and reconstruction. For example,
in a patient who requires mastectomy after failed breast-conserving surgery,
the zone of tissue damage from the original radiation therapy can be assessed
by reviewing the port and boost site films or by examining the irradiated site
for tattoo marks used to align the radiation field. Plans for resection of heavily
irradiated tissues should be made preoperatively in concert with the reconstructive
surgeon, and the relative increased risk of postoperative problems
should be discussed with the patient. This evaluation should include the type
of tissue to be transferred, analysis of potential donor and recipient sites and
vessels, and assurance that the appropriate microvascular equipment is available,
in the event that it is needed during surgery.

Pathologic confirmation of the diagnosis

The treatment of cancer is based almost exclusively on the organ of origin and,
to a lesser degree, on the histologic subtype. Unless the operative procedure is
being performed to make a definitive diagnosis, review of the pathologic material
is needed to confirm the diagnosis preoperatively.

There are few exceptions to this doctrine, and it behooves the surgeon to have
a confirmed diagnosis, including the in situ or invasive nature of the cancer,
prior to performing an operation. This tenet assumes paramount importance
when one is performing procedures for which there is no recourse once the
specimen is removed, eg, laryngectomy, mastectomy, removal of the anal
sphincter, and extremity amputation.

Ironically, in some situations, a preoperative or intraoperative diagnosis cannot
be confirmed, despite the fact that the preoperative and intraoperative physical
findings, laboratory data, and radiologic studies (pre- and intraoperative)
overwhelmingly suggested the cancer diagnosis. The classic example of this
dilemma is the jaundiced patient with a firm mass in the pancreatic head. The
Whipple procedure (pancreaticoduodenectomy) causes significant morbidity
but is required to make the diagnosis and treat the cancer. In any of these
situations, the preoperative discussion with the patient must include the possibility
that the final diagnosis may be a benign lesion.

Resection

The principles of resection for malignant disease are based on the surgical goal
(complete resection vs debulking), functional significance of the involved organ or structure, and the ability to reconstruct the involved and surrounding
structures. Also important are the technical abilities of the surgeon or availability
of a surgical team, adequacy of neoadjuvant and adjuvant therapies, and the
biologic behavior (local and systemic) of the disease. Although "operable" is
used to describe the physiologic status of the patient, the definition of "resectable"
varies, and this term can be defined only in the context of the aforementioned
modifying parameters.

Wide excision
A wide excision includes the removal of the tumor itself and a margin of normal
tissue, usually exceeding 1 cm in all directions from the tumor. The margin
is variable in a large, complex (multiple tissue compartments) specimen, and
the limiting point of the resection is defined by the closest approximation of
cancerous tissue to the normal tissue that is excised.

Wide margins are recommended for tumors with a high likelihood of local
recurrence (eg, dermatofibrosarcoma protuberans) and for tumors without any
reliable adjuvant therapeutic options.

Breast The use of adjuvant radiation therapy has permitted the use of
breast-conserving surgery, which limits the excision of wide margins of
normal breast tissue.

Colon and rectum For carcinoma of the colon and rectum, the width of excision
is defined by the longitudinal portion of the bowel and the inclusion of
adjacent nodal tissue. The principles of wide resection require removal of
normal bowel (including at least 5 cm of uninvolved tissue), the associated
mesenteric leaf, and adjacent rectal soft tissue (mesorectum).

This general principle has been modified in the distal rectum, where lateral
margins are maintained using the principles of mesorectal excision and longitudinal
bowel margins of 2 cm are accepted. This modification reflects the emphasis
on functional results (ie, maintenance of anal continence) and the availability
of adequate adjuvant (pre- or postoperative) radiation therapy to improve
local control.

Pages

 
Loading comments...

By clicking Accept, you agree to become a member of the UBM Medica Community.