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The first decision in the surgical planning in removing a tumor is to determine the “surgical dose.” The surgical dose refers to how aggressive the excision is with respect to the edges of the tumor. The surgical dose has been divided into: intracapsular, marginal, wide, and radical (Figure 1.1). An intracapsular excision is where the capsule of the organ where the tumor arises from (e.g. thyroid gland) or the pseudocapsule of the tumor (e.g. soft tissue sarcoma) is disrupted and the tumor is removed in pieces. A marginal excision is where the removal is done just outside or on the capsule or pseudocapsule. Oftentimes, the tumor is “shelled out.” A wide excision is when the tumor and its capsule are never entered and grossly normal tissue surrounds the specimen. This is often defined as 2–3 cm of normal tissue around the edges of the tumor and one fascial place beneath the cutaneous and subcutaneous tumors. The 2–3 cm of normal tissue is in situ and not histological. A radical excision is the removal of the entire compartment or structure where the tumor is arising from. An example of a radical excision is a limb amputation.

Figure 1.1 Diagram illustrating the different doses of surgery: marginal, wide, and radical being an amputation in this example. Intracapsular is not shown.

Source: Illustrated by Molly Borman.

When removing a tumor, there can be three different goals: curative, palliative, and cytoreductive. These goals will dictate the dose of surgery and several factors will guide which goal should be pursued. The first factor is tumor type. Because benign tumors are limited to their capsule and do not extend into the normal‐appearing tissues, a marginal excision is performed. Malignant tumors, however, have the ability to extend into the grossly normal‐looking tissue at the microscopic level (Figure 1.2). Other factors need to be considered to determine the goal and consequently the dose of surgery. With (most) malignant tumors, when the goal is curative, a wide or radical excision is required. For a palliative or cytoreductive goal, a marginal excision is performed. An intracapsular excision is rarely indicated.

Figure 1.2 Diagram showing the extension of tumor into the grossly normal‐looking tissue. These extensions are most typically at the microscopic level. This is the reason to perform a wide excision (2), as opposed to a marginal excision (1), with the goal to achieve a complete excision.

Source: Illustrated by Molly Borman.

The additional factors to consider to determine the goal of the surgery are: tumor size and location, stage of the cancer, overall health of the patient, risk of the surgery, prognosis, and goals of the owners. Table 1.1 provides examples of how these factors come into play, understanding there are always exceptions or nuances (see section on margins and palliative and cytoreductive surgery).

Because knowing the tumor type is essential in most instances, methods to get a diagnosis are a fine needle aspirate (FNA) or biopsy.