STAR ABSTRACT

Staging lung cancer

Philippe Grenier
MD

In non-small cell lung cancer
(NSCLC), radical surgical resection is
considered to represent therapy most
likely to offer cure. This is usually only
possible if there is no involvement of
unresectable structures and no distant
metastases. In advanced disease, par-
ticularly in the presence of distant
metastases, cure is usually not possible
and palliative chemotherapy and
radiotherapy is considered the most
appropriate therapeutic strategy.

In small cell lung cancer (SCLC)

treatment consists of chemotherapy
with or without additional radiother-
apy. In selected cases of disease limited
to one hemithorax: radical surgery in
combination with chemo- and/or
radiotherapy may provide curative
treatment.

The aim of staging procedures is to
determine the extent of the disease
and, thus, select the most appropriate
treatment. For this purpose it is
important to reliably detect local
tumor extent (T stage: Tl-T4) as well
as the presence or absence of lym-
phatic (N stage: NO-N3) and hemato-
geneous (M stage: MO, Ml) metas-
tases (Table 1).

Staging
system

Revisions in stage grouping of the
TNM subsets in the international sys-
tem for staging lung cancer were
made 1997, to provide greater speci-
ficity for identifying patient groups
with similar prognoses and treatment
options. Patients who are likely to
benefit from surgical resection are
those with localized disease. Only
stages I, II and IlIA can be considered
as technically resectable (Table 2).
Patients considered as definitely unre-
sectable are those having distant
metastases (Ml), controlateral or sub-
clavian lymph node metastases (N3)
or tumor classified T4.

The local extent of tumor affects
the extent of surgery required for rad-
ical resection. Generally, a tumor sur-

Table I. TNM description for staging lung cancer (1)

TX Primary tumor cannot be assessed or cannot be visualized despite presence of malignant cells in sputum or bronchial wash-
ings

TO No evidence of primary tumor
Tis Carcinoma in situ
Tl 'Iumor s 3 cm surrounded by lung or visceral pleura; without bronchoscopic evidence of infiltration of main bronchus
T2 Tumor> 3 cm / infiltration of main bronchus> 2 cm to carina / infiltration of visceral pleura / obstructive pneumonitis or

atelectasis extending to the hilum but not involving entire lung
T3 Infiltration of main bronchus < 2 cm to carina / infiltration of parietal or mediastinal pleura, chest wall, pericardium,

diaphragm / obstructive pneumonitis or atelectasis of entire lung
T4 Infiltration of heart, great vessels,trachea, esophagus, vertebral body / malignant pleural or pericardial effusion / satellite tumor

nodules within the same lobe

NX Regional lymph nodes cannot be assessed
NO No regional lymph node metastases
Nl Metastasis to ipsilateral intrapulmonary, peribronchial or hilar lymph nodes
N2 Metastasis to ipsilateral mediastinal and/or subcarinallymph nodes
N3 Metastasis to contralateral hilar, contralateral mediastinal, ipsi- or contralateral scalene or supraclavicular lymph node metas-

tases (note: cervical or abdominal lymph node metastases are considered Ml)

MX Presence of distant metastases can not be assessed
MO No distant metastases
Ml Distant metastases (brain, adrenal, skeleton etc.), lymphatic distant metastases (cervical and abdominal lymph nodes),

satellite tumor nodules in other lobes

14 SA JOURNAL OF RADIOLOGY • December 2002



STAR ABSTRACT

TableII. Stagegrouping - TNM
subsets (1)

StagelA Tl NO MO
StageI B T2 NO MO
StageIIA Tl Nl MO
StageII B T2 Nl MO

T3 NO MO
StageIII A T3 Nl MO

Tl-3 N2 MO
StageIII B T4 NO-2 MO

Tl-4 N3 MO
StageIV Tl-4 NO-3 Ml

rounded by aerated lung with no
invasion of the main bronchus (Tl)
can be resected by lobectomy, whereas
infiltration of the main bronchus,
chest wall, diaphragm or medi-
astinum requires more aggressive
surgery (pneumonectomy or sleeve
resection, resection of chest wall,
diaphragm etc.) which is associated
with higher morbidity and mortality.
Infiltration of structures that are
either unresectable (heart) or in
which resection is usually associated
with higher morbidity or mortality
(esophagus, brachial plexus, spine,
aorta, superior vena cava etc.) are usu-
ally considered inoperable, particular-
ly in view of the usually poor survival
associated with these degrees of
tumor extent. Other features do not
affect resectability but reflect a more
extensive tumor spread such as the
presence of satellite tumor nodules in
the same lobe.

As treatment options in small cell
lung cancer are more limited a simpli-
fied staging system is often used in
clinical practice (Table 3).

Tumour extent
CT continues to playa major role

in preoperative staging of non-small
cell lung cancer for selecting those

TableIII. Staging of small celllung cancer (VeteransAdministration Lung Cancer
Study Group) (2)

Verylimited disease (VLD)
StageI and II
Limited disease (LD)
Primary tumor limited to one hemithorax
Ipsilateralhilar,mediastinalor supraclavicularlymph node metastases
Contralateralmediastinallymph node metastases
Atelectasis
Paralysisof recurrent or phrenic nerve
Smallpleural effusionwith no malignant cells
Extensivedisease I (EDI)
Contralateralhilar or supraclavicularlymph node metastases
Infiltrationof chestwall
Pleuraleffusion(exceptfor smalleffusionwith non malignant cells)
Superiorvena cavasyndrome
Metastasesto controlaterallung
Extensivedisease II (EDII)
Pleuriticcarcinomatosis
Lymphangiticcarcinomatosis
Distant metastases

patients with localized disease who are
likely to benefit from surgical resec-
tion. Certain CT findings have been
demonstrated as being diagnostic of
unresectable disease. In many of these
situations, biopsy proof of diagnosis is
necessary but thoracotomy is not
indicated. Although gross mediastinal
invasion can be confidently diagnosed
with CT, the contiguity of tumor with
adjacent mediastinal structures is not
equivalent to definite invasion.

MR has the same limitations as CT
in distinguishing tumor contiguity
from tumor extension into mediasti-
nal structures.

Owing to its superior contrast res-
olution, MR may demonstrate subtle
chest wall invasion and be superior to
CT in this regard. MR is also thought
to be more accurate that CT in depict-
ing chest wall invasion from superior
sulcus tumor that commonly involves
the vertebra posteriorly, and the sub-
clavian vessels and brachial plexus

15 SA JOURNAL OF RADIOLOGY • December 2002

anteriorly. On the other hand, using
helical scanning with thin collima-
tion, bolus injection of contrast medi-
um, and sagittal and coronal recon-
structions, the anatomical environ-
ment of the plexus may also be accu-
rately assessed with CT. MR remains
an alternative only in cases in which
the CT findings are inconclusive and
in those in which extension into the
neural foramina and epidural space is
suspected.

Both CT and MR! cannot reliably
differentiate between benign and
malignant pleural and pericardial
effusions. Presence of malignant
pleural or pericardial effusion is best
diagnosed by demonstration of
malignant cells at aspiration.

Nodal extent
CT is very valuable in detecting

mediastinal lymph node enlargement.
Low sensitivity of CT is due to its
inability to detect microscopic metas-



STAR ABSTRACT

tases within normal-sized lymph
nodes. Low specificity arises from the
frequent occurrence of enlarged
hyperplastic nodes. Consequently, all
patients with abnormal mediastinal
lymph nodes on CT scans need
lymph node resection or biopsy. MR
has no superiority over CT and is not
indicated in this regard. Positron
emission tomography (PET) with F-
18 2 fluoro-2-deoxy-D-glucose
(FDG) is more sensitive and specific
than CT for nodal staging in lung can-
cer.

Mediastinoscopy has proven to be
unnecessary in patients with CT evi-
dence for stage I disease and a negative
PET of the regional nodes. Increased
FDG uptake in hilar and mediastinal
lymph nodes can be used to direct
surgical nodal sampling. The com-
bined use of CT and PET to stage
intrathoracic nodal metastases is not
only clinically useful but also cost-
effective. PET reduces the probability
that a patient with unresectable medi-
astinal nodal metastases will undergo
an attempt at curative resection.

Distant
metastases

In most institutions lung cancer
patients undergo routine staging pro-
cedures including chest radiographs,
CT of the chest, abdomen and brain,

bone scintigraphy and ultrasound
examination of the abdomen. Because
the adrenal glands are the most com-
mon site for extrathoraeie metastases,
CT examination should include the
upper abdomen. An adrenal mass
however may represent an incidental
adenoma. Most incidental non-
hyperfunctioning adrenal adenomas
are less than 3 cm in diameter and of
uniform low attenuation « 10 HU),
because of their fat content. Routine
unenhanced CT of the adrenal glands
allows accurate prospective character-
ization of many adrenal masses in
patients with lung carcinoma.

In institutions in which PET is
readily available, this may be per-
formed as the only additional exami-
nation after CT, as it is the most accu-
rate non-invasive imaging technique
to confirm or exclude both lymph
node and distant metastases (except
for brain metastases) in a single exam-
ination. Whole-Body FDG-PET
improves the detection of extratho-
racic disease and alters management
in up to 40% of cases.

Conclusion
CT remains the imaging technique

of choice in staging lung cancer.
Despite its limitation, CT is indicated
in order to determine the extent of
the primary tumor, to evaluate the

mediastinal space for the presence of
nodal enlargement, and to screen
metastatic disease in the adrenal
glands. MR is only indicated as an
additional examination in patients
with superior sulcus tumor. Whole
body PET is the best technique for
screening both lymph node and dis-
tant metastases.

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