Lung Cancer.pdf

Clinical Examination of Patients with Suspected Lung Cancer 31
dictated by the circumstances of the case. Certainly, in patients experiencing
neurological symptoms for which palliative radiation therapy or
resection would be considered, CT or MR imaging of the brain is indicated.
Similarly, patients experiencing bone pain for which palliative radiation
therapy would be offered should have a bone scan with or without
plain films.
However, in the absence of neurological symptoms and bone pain, routine
imaging of the brain and bones is not necessary unless the finding of
occult metastases in these sites would significantly alter treatment. For example,
in patients who otherwise have limited-stage SCLC and patients
who have stage III NSCLC, we typically do brain and bone scans even in
the absence of symptoms because finding occult brain or bone metastases
in these patients would drastically alter therapy—from multimodality
treatment with “curative” intent to, generally, chemotherapy only. In contrast,
in patients who already have documented extensive-stage SCLC or
stage IV NSCLC, these scans need not be done as the discovery of additional
occult metastases will generally not alter treatment. In the staging of
patients with potentially operable stage I or II NSCLC, brain and bone
scans are generally not recommended in the absence of other findings that
would indicate metastasis to these sites unless the clinician’s index of suspicion
remains high. For example, brain and bone scans might be considered
in an asymptomatic patient with stage I or II poorly differentiated
adenocarcinoma but would probably not be necessary in a patient with
operable bronchioloalveolar carcinoma, a tumor with a much lower likelihood
of occult metastasis.
In addition to the roles of MR imaging in screening for brain metastasis
and evaluation of suspicious adrenal enlargement, MR imaging also has a
role in the preoperative evaluation of patients with superior sulcus tumors
and patients with other potentially operable T4 lesions. The presence
of chest wall or vertebral body invasion is often difficult to distinguish
with chest CT alone. MR imaging of the chest is generally superior in this
regard and is helpful to the thoracic surgeon in planning resection.
Positron emission tomography (PET) is able to characterize lung lesions
reliably in most cases, failing to detect only very small lesions and
tumors of a very indolent nature. PET may therefore play a role in the
evaluation of patients with solitary pulmonary nodules. PET scanning is
also a useful tool in documenting the presence of mediastinal lymph node
metastases, with reported sensitivity and specificity of more than 90%. In
this regard, PET is more accurate than CT scanning, although PET images
lack the anatomic precision seen with CT scans. PET scans also have potential
utility in detecting otherwise undetected widespread metastases in
patients for whom curative resection is being considered. At this time, our
recommendations regarding the optimal use of PET scans in the staging of
lung cancer are still evolving. The controversy surrounding PET is discussed
in more detail in chapter 3.