Recent Newspaper & Online Columns by Kate Scannell MD

CT scans: Radiating hope and concern about cancer

November 25, 2010

Tags: CT scans, lung cancer, screening, Kate Scannell

By Kate Scannell, Syndicated columnist, Bay Area News Group
First Published in Print: 11/14/2010

LAST WEEK'S news radiated hope that smokers' lung cancer mortality rates might be decreased through serial CT scanning -- as it also radiated concerns about the safety of CT scanning in general.

Last week, researchers from the National Cancer Institute proclaimed that the lung cancer death rate for smokers could be lowered by 20 percent if smokers underwent regular CT screening to detect early evidence of cancer. Essentially, the researchers gave 53,000 current or former smokers either a standard chest X-ray or a CT scan on three occasions -- once at the start of the study and twice over the subsequent two years. After tracking these smokers for five years, researchers found that 354 people who received CT scans had died of lung cancer, versus 442 people who received chest X-rays. In other words, 88 fewer people died in the first group, representing a 20 percent decrease in the death rate.

So, what should we make of these findings?

Certainly, it's wonderful news that CT screening led to fewer deaths among current or former smokers. If the researchers' findings are reliably replicated and screening becomes routine medical practice, each decade we might witness hundreds of thousands of additional lives saved.

Indeed, if 159,000 people in the U.S. die each year with lung cancer, a 20 percent reduction in the death rate would translate into nearly 32,000 saved lives annually. In my book, that's a smoking hot success!

Yet, the story is not so simply told. Whenever we celebrate one new medical innovation or bedazzling research discovery, we tend to isolate it out from the broader medical and social context where it actually resides and resonates with fuller meaning. So let's turn a few more pages and read between the lines.

Already, some health care experts are speculating that the new study might encourage widespread CT screening of smokers. If so, the medical and fiscal impact would be sizable, considering that about 90 million current or former smokers live within the U.S. Tens-of-millions more people might be fighting over old magazines within overcrowded radiology waiting rooms every year. It could mean that, at a cost of about $300-$400 per CT scan, billions of dollars would be added annually to our skyrocketing national health care costs.

It's hard to blow smoke at such cost projections, particularly during our economic downturn and contentious health care reform battles. As things now stand, neither Medicare nor most private health insurers cover the cost of CT scans when employed for prevention or screening purposes.

Consequently, this raises questions about who ought to be responsible for CT screening costs. Will smokers pay for them out-of-pocket, or demand that they be covered by insurance? Will the powerful tobacco lobby persuade our politicians to legislate in favor of Medicare and MediCal coverage?

If Medicare does decide to pick up the hefty tab, many taxpayers will grumble. Rightly or wrongly, they will complain about subsidizing addictions and poor "lifestyle choices" to smoke. They will make moral appeals to personal responsibility, social solidarity, and concern for the common good, demanding that smokers assume financial liability for self-inflicted harms.

Looking at the new study from a slightly different angle, consider this statistic: It required 300 current or former smokers to be screened by CT scans for every one person who would have otherwise died during the study. In other words, at substantial costs of time and money, the CT scans did not benefit 299 of every 300 people who underwent them.

This lights up another burning question: What makes a test or treatment "worthy" to us? As patients, do we want to take a pill or test that, in all probability, is likely to benefit only one of every 300 partakers? One of every 500? One in a million?

The question assumes even greater dimensionality when we also consider the potential side effects of the pill or test -- not just the likelihood of its benefit. In our case at hand, what probability of human harm should trump a 1-in-300 probability of benefit from CT scanning?

In considering CT scanning, we need to think about radiation exposure -- a known cancer risk itself -- and the side effects from investigations of incidental findings.
For example, the radiation exposure from a single chest CT scan can be equivalent to several hundred chest X-rays, and researchers have established real risks of developing cancer from even a single CT scan. For example, a study in last December's Archives of Internal Medicine found the risk of developing cancer from some common varieties of CT scans could at times be more than 1 in 80.

That study also found dramatic 13-fold variations in the doses of radiation that were delivered to patients who received the same CT test. Last week, responding to reports of nearly 400 patients having received wildly excessive radiation doses from CT brain perfusion scans, the FDA issued a warning to all CT manufacturers. Among its many advisements, it requested that they improve their user manuals and the training of scanning personnel.

Finally, 20 to 60 percent of screening CT scans for current or former smokers will show abnormalities -- most of which turn out to be benign. But to find that out, one often has to undergo lung biopsies, additional CT scans, or chest surgery for a definitive diagnosis -- all costly and with potential risks.

So, again, at what level of risk -- one in 80? one in 100? 穆hould a patient take a test that has a 1 in 300 chance of providing benefit?

I don't have the answer. But the bottom line is that no new medical discovery stands in isolation or apart from social meaning. Medicine is an art complicated by science. And anyone who tells you otherwise is simply blowing smoke.
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Kate Scannell is a Bay Area physician and syndicated columnist. Her new novel is "Flood Stage."

ゥ Copyright 2010, Kate Scannell

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