|
Most
oncology professional bodies to not recommend lung cancer
screening for asymptomatic individuals at risk for lung cancer.
However, physicians and patients may decide that there is
sufficient evidence to warrant the use of screening tests
on a case-by-case basis. Previous studies using chest X-rays
at various intervals have not altered survival rates from
such screening strategies. Recent improvements in CT technology
have made lung cancer screening feasible. In the low dose
CT technique, there is no need for intravenous contrast administration
and the scanning time is about 20 seconds.
Prevalence data from the Early Lung Cancer Action Project
from U.S., which evaluated about 1000 patients , and from
the mass screening for lung cancer project with mobile spiral
CT scanner in Japan (n=5483), have shown the technique to
be favourable. CT detects 10 times more cancers than standard
screening with plain radiographs. The majority of the cancers
detected by CT are in the early stage. The technique should
result in better survival rates in lung cancer patients, although
this has to be proven with controlled trials.
Whether this screening modality will be widely accepted remains
to be decided awaiting prospective studies. Such studies will
validate if the survival benefit makes this screening strategy
cost effective considering the additional cost of procedures
arising out of false positive cases. When offered outside
of a clinical trial, patients should be properly counselled
about the high presence of false-positive results requiring
unnecessary invasive procedures.
Dr James Khoo
Head, Diagnostic Imaging
|
