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                                      David C. Rice, MB, BCh
                                Associate Professor of Surgery

        The University of Texas, M.D. Anderson Cancer
                                               Center
Staging refers to the process of defining the anatomic extent of

a tumor. Based on extent cancers are placed into one of 4

stage groupings which encompass the spectrum from early

stage localized tumors (Stage I) to advanced stage tumors that

have spread to other organs (Stage IV). The purpose of

staging is to define groups of patients who have similar

prognosis and to guide appropriate therapy. It is essential that

cancers be properly staged prior to embarking on treatment so

that the most effective form of therapy can be delivered to the

patient. Staging that occurs based on clinical information

available prior to surgery is called ‘clinical staging’ and is

generally less accurate than ‘pathologic staging’ which is based

on precise anatomic information available only after the tumor

has been examined after surgery.
The most widely accepted staging system for mesothelioma is
that endorsed by the International Mesothelioma Interest
Group (IMIG) and the American Joint Commission on Cancer
(AJCC). This system defines stage according to the extent of
the tumor itself, the involvement of lymph glands (or nodes)
and the presence of metastases to other organs.


The current AJCC staging system is under evaluation and will
probably be revised within the next few years.


Other staging systems in clinical use include the Brigham and
Women’s Staging System and the Butchart Staging System
In its earliest manifestation, mesothelioma appears as
multiple small white nodules that involve the thin translucent
lining of the chest wall (parietal pleura). In general there is
diffuse involvement of the pleura rather than a single discrete
focus of tumor. This stage is rarely diagnosed and may be
seen as either slight thickening of the pleura on CT scans or
as fluid accumulation between the chest wall and lung (pleural
effusion).
As tumor spreads it will involve the thin pleural lining the lung
surface (visceral pleura). The radiographic findings are similar
to Stage Ia except there may be nodularity of the pleura seen
in between the different lobes of the lung.
As tumor grows it may invade into the lung or diaphragm (the
muscle in between the chest cavity and the abdomen). CT
scan is imprecise at accurately predicting either lung or
diaphragm invasion, although in general the greater the degree
of pleural thickening and tumor bulk, the greater the chance of
lung or diaphragm invasion.
Mesothelioma may grow across the pleural lining of the chest
wall to invade into the substance of the chest wall itself. When
this occurs in a single region it denotes Stage III. The tumor
frequently invades the chest wall at the site of previous surgical
incisions. CT scan and MRI are useful for determining chest
wall invasion.
Mesothelioma can also invade into the fibrous sac that
surrounds the heart (pericardium). When there is only
superficial invasion it also denotes Stage III. Lastly,
mesothelioma, like other tumors can spread to lymph glands.
When it spreads to glands in the chest on the same side as the
tumor it denotes Stage III. Radiographic imaging (CT scan,
PET scan or MRI) is inaccurate at determining pericardial
invasion or nodal involvement.
When mesothelioma invades multiple areas of the chest wall,
invades through the pericardium or diaphragm, involves lymph
glands outside the chest or spreads to other organs it denotes
Stage IV disease. Chest wall invasion may be identified with
CT or MRI, however they are poor at determining invasion
across the diaphragm or pericardium.
PET scan is a very useful technique for determining whether
the tumor has spread outside the chest.
 Your doctor may order a variety of tests to determine the stage
 of your tumor. The results of these tests will help determine
 which therapy will be the most appropriate for your tumor. Non-
 invasive tests usually involve medical imaging or blood testing.
 Invasive tests are those that involve a minor surgical procedure
 or a image-guided biopsy.



Non-Invasive Tests
 Serum Mesothelin – Measures blood levels of a protein
 secreted by certain mesotheliomas.
 Chest X-Ray – Defines extent of tumor within the chest.
 CT scan – Defines extent of tumor but gives more detailed
 information than chest x-ray
 MRI – Useful if chest wall invasion suspected on CT scan.
 PET scan – Very useful for determining whether tumor has
 spread to other organs outside of the chest.
Non-Invasive Tests
 CT-guided core biopsy –Diagnosis of mesothelioma.
 Outpatient procedure.
 Thoracentesis – Outpatient evaluation of fluid from chest.
 Diagnostic only 30% of the time.
 Thoracoscopy – The most accurate method of diagnosing
 mesothelioma. Involves general anesthetic and a small incision
 on the chest.
 Mediastinoscopy – Outpatient surgical procedure to evaluate
 if lymph glands in the center of the chest contain tumor.
 Involves a small incision on the neck.
 Endobronchial ultrasound needle biopsy – Outpatient
 procedure that evaluates if lymph glands in the center of the
 chest contain tumor. Does not involve surgery.
 Laparoscopy – Outpatient surgical procedure to evaluate if
 tumor has spread to the abdomen.
Surgical Staging
 In patients who are deemed candidates for surgery based on
 non-invasive tests, surgical staging is usually performed to
 ensure that tumor does not involve the lymph glands or the
 abdomen. This involves a single, short outpatient anesthetic
 where laparoscopy and endobronchial ultrasound guided fine
 needle aspiration are performed simultaneously. Occasionally
 thoracoscopy may be required to obtain additional tumor tissue
 to confirm the diagnosis of mesothelioma. In this case patients
 usually stay over night in hospital and go home the following
 day.