1 Classification Criteria

Though morphological characteristics recognized in histopathologic grading of tumours generally correlate with biological behavior, a more complete assessment of the tumor and its spread(i.e., staging) is necessary for planning treatment and comparing results. No single clinical staging system for musculoskeletal tumours and sarcomas has been accepted.

At the present time two systems of staging are being used:

• The TNM staging system that recognizes recognizing tumor type, grade (G), size (T) and presence of lymph nodes (N) or distant metastases (M). 
• The Enneking staging system mainly used for musculoskeletal tumors is based on histologic subtype, grade and the anatomical setting (intra or extra compartmental).

Efforts are currently being made to consolidate these two systems into a more meaningful staging system.

2 Staging Diagram 

The Staging sheet includes a statement of the site of the primary, the final diagnosis and the staging using the Enneking staging system. It must be signed and dated by the attending physician.

3 Investigations for Staging

It is incumbent upon the primary care physician:

• to recognize the organic basis of the patient's complaint of pain, swelling or dysfunction and 
• to obtain accurate clinical information about the tumor by careful history and physical examination

A high index of suspicion of malignancy is essential, for example, in a teenager with knee pain unrelated to trauma or persisting longer than it should or in the patient over fifty years old with the same clinical presentation in whom metastatic disease to bone becomes increasingly common.

Similarly, when the complaint is a deeply located large soft tissue mass, soft tissue sarcoma must be considered in the differential diagnosis so that appropriate baseline investigations may be done.

The Musculoskeletal Tumor and Sarcoma Group have become increasingly aware of frequently encountered pitfalls in early management. These make the definitive treatment of these lesions more difficult, more complicated and less satisfactory. It has been our experience that nearly one in three patients have not received ideal oncologic management due to errors in investigation, diagnosis or treatment.

The major problem encountered is related to the biopsy which is discussed here prior to other considerations, ONLY to emphasize that it should NEVER be done before other appropriate staging procedures. Caution should be exercised in carrying out invasive procedures. Above all, a BIOPSY must not precede other investigations for fear of interfering with their results.

BIOPSY

The goal of biopsy is to harvest a representative sample of the tumor without compromise of the definitive management. Sarcomas are tumors that are known to be able to spread by implantation. It should be done only when

• all anticipated investigations are completed and, 
• in the case of musculoskeletal tumors, after full consultation with an orthopaedic oncologist so that the best site for biopsy can be chosen so that most informative specimen can be examined by pathology 
• For non-musculoskeletal sites, consultation with a surgical oncologist is important for biopsy planning. There are surgeons in various subspecialties area if general surgeon is not the most appropriate – see relevant site in CMM for Gynecology, Urology, central nervous system, thorax, and Head and Neck consultant surgeons. If any doubt who to call, you are encouraged to ring BCCA referral desk for contact initiation – (604)877-6066 or for out of area 1-800-877-6000, X 6066.

Investigations may include:

1. PLAIN RADIOGRAPHS
A plain X-ray is the most important initial investigation of a potential bone neoplasm. It is helpful in the investigation of soft tissue lesions particularly if the lesion is mineralized.

2. MAGNETIC RESONANCE SCAN (MR SCAN)
The MR scans have become vital in the management of musculoskeletal tumours and sarcomas because they:
a) provide detailed information that has increased our ability to safely excise lesions that formerly were felt to be inoperable.
b) are particularly helpful in evaluating the extent of soft tissue lesions and their relationships to surrounding vital structures
c) aid in the evaluation of the medullary canal of long bones valuable in the search for such things as skip metastases in osteosarcomas.
d) on occasion may lead to a diagnosis based only on the MR signal characteristics of the lesion, as is the case in intramuscular lipomas or low-grade liposarcomas (lipoma-like).

The MR scan is severely affected by the BIOPSY PROCEDURE and should be done BEFORE THE BIOPSY is performed. The scan is very sensitive to reactive edema and post-procedural scans can be difficult to interpret.

3. COMPUTERIZED TOMOGRAPHY (CT SCAN)
This examination has become an essential part of the staging studies necessary for planning treatment, particularly FOR:
a) STAGING the lungs (The chest CT scan is very sensitive and false positives are common and over interpretation is to be avoided. Plain chest radiographs are usually recommended for chest follow up.)
b) GUIDING core needle biopsies FOR most cases.

4. RADIONUCLEOTIDE SCAN ("BONE SCAN")
A total body technetium scan will give useful information:
a) not only about a presenting bone lesion
b) but also about possible multiple lesions and bone reaction to overlying sarcomas.

A bone scan is generally not indicated in soft tissue tumors.

5. TOMOGRAPHY - NO LONGER ROUTINELY USED.

6. ANGIOGRAPHY
a) has a limited place in investigation of musculoskeletal tumours and sarcomas
b) is useful in the investigation and treatment of hemangioma, arterio-venous malformation, and metastatic renal and thyroid carcinoma.

7. ULTRASOUND EXAMINATIONS
Ultrasound has no routine application in the pre-biopsy evaluation of solid soft tissue lesions occurring at any site. They maybe misleading, particularly when the radiologist attempts to make a diagnosis. The ultrasound scan simply serves to delay the diagnostic process, and should not be ordered. The single most important test for a bone or soft tissue sarcoma is the magnetic resonance scan (MR scan).