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Staging of Lung Cancer
One of the first things that your
physician will do after making a diagnosis of lung cancer is to
determine the stage of the disease.
Staging will determine 1) which treatment modalities will be used
and 2) chances of long-term survivability (prognosis). In
1973 the American Joint Committee on Cancer proposed a scheme for lung
cancer based on the TMN system first proposed by Denoix in 1946. The
staging scheme was revised in 1986 and again in 1997.
This system is NOT used for small cell lung cancers. Small cell lung cancers are
staged as either limited stage or extensive stage.
Limited stage small cell lung cancers are loosely defined
as those that are contained to a small enough area to allow a
“tolerable” radiation therapy port. This usually means that the
cancer is contained in one lung, and may include involvement of the area
between the lungs and adjacent lymph nodes.
Extensive stage means that the tumor is either
metastasized to other sites, or is too widespread to be considered
limited. Staging of non-small cell lung
cancers: What is TMN?:
T stands for tumor size and invasiveness.
The T number can range from T1 to T4.
T1 and T2 are differentiated primarily
on size (<3 cm = T1, >3 cm = T2) and if the tumor is visible
within a lobar bronchus (T2). T3 tumors involve the chest wall, but may
be resectable (operable). T4
tumors are not surgically resectable because they have invaded the
mediastinum (the area and organs between the lungs)
and involve the heart, great vessels, trachea or esophagus, or
because they involve the pleura (lining of the lung) with a malignant
pleural effusion (accumulation of fluid around the lining of the lung).
N stands for Nodal involvement (lymph nodes) and is staged from
N1 to N3. M stands for the
presence (1) or absence (0) of metastases (spread to a distant site).
Ok with
the above in mind, let’s chart out the staging of non-small cell lung
cancer. Occult
Carcinoma:
These patients have malignant cells in their secretions, but no
tumor is evident by bronchoscopy or by x-rays or scans.
Stage
IA and Stage IB:
In 1997 Stage I cancers were divided into A and B.
All stage I lung cancers are completely contained within the lung
with no evidence of lymph node involvement or metastases.
Stage IA have a tumor of less
than 3 cm. Stage IB have a
tumor of greater than 3 cm and are somewhat invading surround local
areas. Stage IA
non-small cell lung cancers comprise 13% of
newly diagnosed lung cancers while stage IB comprise 23%.
Patients with stage I disease are typically treated by surgery. Additional therapies such as radiation and chemotherapy do not produce better results. 5-year survival for sate IA is 67% and for stage IB is 57%. We continue our discussion of
staging lung cancers. Staging
will determine 1) which treatment modalities will be used and 2) chances
of long-term survivability (prognosis).
This article picks up with stage II non-small cell lung cancers.
The TMN method of staging discussed here is not used for small
cell lung cancers. See part
1 of this series for a discussion on staging small cell lung cancers. Stage II disease, like stage I
disease, is further broken down into IIA and IIB. Stage IIA disease is
defined as T1, N1, MO. This
means that 1) the tumor is less than 3 cm with no evidence of invasion
into the main bronchus (the main airway) 2) There is involvement of
local lymph nodes on the same side of the chest (hilar, intrapulmonary,
peribronchial) and 3) there is no metastasis to other sites such as the
liver or brain. Stage IIB disease is defined as T2, N1, M0 or T3, N0, M0. Lets break each of these down. T2, N1, M0: There is a tumor (T) that has any of the following characteristics. · Greater than 3 cm · Involves the main bronchus · Invades the surrounding tissue of other local organs · Is interfering with the function of the lung, such as partial collapse There is involvement of
local lymph nodes on the same side of the chest, and there is no
metastasis. T3,N0, M0:
There is a tumor that is invading the chest wall or the
structures of the chest center. There
is no lymph node involvement and there is no metastasis. Surgery
is the preferred method of treatment for Stage II disease.
Patients who are inoperable but with sufficient lung function may
benefit from radiation. Patients
who receive radiation alone at this stage have a 20% chance of 3-year
survival. Patients with
stage II disease who have surgery have an approximate 40% chance of
5-year survival. There is
some discussion in the medical community that postoperative chemotherapy
may be of some benefit. Those
wishing to do so can enter clinical trials which are evaluating the
value of post-surgical chemotherapy. The
surgical treatment of lung cancer involves lobectomy, pneumonectomy, or
segmental, wedge or sleeve resection.
Let’s define these. Lobectomy:
Removal of one of the lobes of the lung.
The right lung has 3 lobes and the left lung has 2 lobes. Pneumonectomy:
Removal of an entire lung, or more than one lobe of the lung. Segmental, or Wedge Resection: A portion of a lobe is removed Sleeve resection: Removal of a segment of the windpipe in patients who have a central tumor, then the two ends are stitched together. Article by Michael Guthrie, R.Ph. |
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"Alternative Cancer Treatments"
Michael Guthrie,
R.Ph. CGP 2003-2006
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