Is the Spiral CT Scan a Good Idea for Lung Cancer Screening?
The death of Peter Jennings from lung cancer, and then the news right afterwards
that Dana Reeve, widow of Christopher Reeve, has lung cancer, has made a lot of
people a little bit nervous about getting the disease themselves. Lung cancer is
the leading cause of cancer-related death in this country, among both women and
men. According to estimates by the American Cancer Society, there will be
172,570 cases of lung cancer diagnosed this year, and 163,510 people will die of
Researchers believe that about 90 percent of the most
common types of lung cancer are caused by smoking or by inhaling secondhand
smoke. Even after you quit smoking, you’re still at increased risk of developing
lung cancer, although the risk does decrease with time.
Lung cancer causes about 29 percent of all cancer deaths.
The five-year survival rate for lung cancer is about 15 percent. The problem is
that most people who are diagnosed with lung cancer have already begun having
symptoms and their cancers are more advanced or have spread (metastasized) to
other parts of the body.
Can you detect lung cancer before symptoms begin?
Generally, traditional X-rays of the lungs can detect tumors that are about the
size of a quarter or larger. In most cases, at this point the tumor has reached
a more advanced stage and patients have already begun having symptoms. This is
why X-rays aren’t used to screen for lung cancer. Symptoms of lung cancer
- Persistent cough
- Sputum that contains blood
- Chest pain
- Frequent pneumonia or bronchitis
Remember, a screening test is done to detect cancer before
it causes symptoms. Common cancer screening tests include mammograms, to detect
breast cancer, and colonoscopy, to detect cancer of the colon.
A newer screening test, called the spiral CT scan, is able
to detect lung tumors as small as the diameter of a soda straw. During the test,
the CT machine rotates around you to produce an image of your entire chest in
about 20 seconds.
There are medical professionals who believe that
eventually, it will become common for long-time smokers older than 60, including
those who have quit smoking, will be good candidates for the spiral CT scan. In
ongoing clinical trials testing the effectiveness of the CT scanner, tumors have
been found before they have begun to cause symptoms. But there haven’t been
enough large, long-term clinical trials that have proven that this type of
screening will improve survival for patients.
Concerns about spiral CT scanning
In addition to there being no proof that spiral CT scans
can extend life expectancy for lung cancer patients, there are other reasons to
exercise caution with the scans, including:
- Overdiagnosis—The spiral CT scan can detect tiny tumors
that would never be life-threatening.
- False positives—The scan can detect small nodules that
do not turn out to be cancerous.
In both of these instances, doctors would need to conduct
further testing to determine whether the findings of the CT scanner do indicate
cancer. That means that patients have to undergo needle biopsies of lung tissue
or even surgical removal of a nodule.
There’s also the issue of cost. The spiral CT scan can cost
from $250.00 to $1,000.00. Until there’s clear evidence, produced from large
clinical trials, that using the spiral CT scan for cancer screening does, in
fact, save lives, it won’t become a common cancer screening tool.
Cancer Society; The National Cancer Institute; The New York Times, “What
an Extra Eye on Cancer Can do for You,” 16 August 2005.