[MOL] Gusto for screening high-rish lung cancer.... [00022] Medicine On Line


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[MOL] Gusto for screening high-rish lung cancer....



DURHAM, N.C.-The gusto for screening high-risk patients for lung
cancer with low-dose spiral CT may be running roughshod over the
confusing and scant evidence of potential significant benefit.
  
So conclude Duke radiologist Edward F. Patz Jr. and colleagues in a
review article in the Nov. 30 New England Journal of Medicine. They
argued that though smaller lung lesions may be detected with the new
technology, there’s no reliable evidence that smaller is more curable.
  
In what amounted to a pointed editorial, they pleaded with the
clinical community to resist "public and political pressure"-stemming
from low-dose CT prevalence-screening data-to change clinical
practice hurriedly. In particular, they urged that any idea of mass
lung-cancer screening before careful trials are done should be put
on hold.
 
"There should be no compromise or shortcuts in the rigorous
scientific process required to determine whether this practice is
justified," they urged.
  
They warned that all too often in recent years clinicians have been
so seduced by rosy early studies that they took experimental
procedures into standard practice prematurely. Only later did
randomized studies reveal no benefit. As a prime example, they cited
the false promise of high-dose chemotherapy with stem-cell rescue
for metastatic breast cancer.
  
Much of the enthusiasm for lung-cancer screening by low-dose spiral
CT springs from the Early Lung Cancer Action Project, spurred by
Cornell’s Dr. Claudia I. Henschke and her 1999 interim paper in
Lancet on 1,000 high-risk smokers over age 60. Her study confirmed
that low-dose CT was a sensitive screen for lung nodules.
  
"The true clinical significance of the small [lung] tumors found by
screening is unknown, and their effect on mortality awaits future
investigations," the NEJM authors said. No convincing data, they
added, confirm that a primary 5-mm lung tumor has a significantly
better prognosis than a 10-mm tumor or even a 30-mm tumor.
  
They cited a study of 510 node-negative patients by Dr. Patz and
colleagues, published in Chest this year, showing no outcome
difference between patients with 3-mm nodules and those with 1-mm
masses.
  
"In fact, clinical studies have confirmed that patients with small
tumors can harbor malignant cells in normal-appearing lymph nodes
that are detectable only by immunohistochemical or reverse-
transcriptase PCR assays," they said.
  
What’s more, they noted, low-dose CT detects an indeterminate nodule
in 23% of all screened patients. "The majority should be benign, but
evaluation of all those nodules is not a trivial problem. This could
create a very expensive clinical quagmire."
  
The National Cancer Institute, which has been cautious in its
approach to low-dose CT screening, is running a yearlong study with
3,000 current and former smokers to see whether a randomized trial
is feasible. According to the NCI, about half of the hospitals in
the United States own spiral-CT units, and some institutions are
advertising the scans aggressively to smokers and ex-smokers for the
early detection of lung cancer. 
 
If NCI decides a randomized trial is feasible, it plans a study of
tens of thousands of participants that will take at least five years.
It will have the statistical power to detect a 20% mortality
reduction.
 
 
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