CT Screening for Lung Cancer

“If you order a test, you’d better know what you’re going to do if it’s positive or if it’s negative.”

Truer words were never spoken by my chief resident in medical school.

So it was interesting to read this morning’s Wall Street Journal article criticizing a doctor’s perspective that CT scanning to detect early lung cancer might be dangerous when applied to the general population of at-risk smokers. People are aghast that this UCLA doctor took monies from the tobacco industry to testify in a court case about the pitfalls of such testing and applied those funds to an “educational fund” at UCLA.

In a dispute with broad implications for cancer treatment, patient advocates and congressional overseers are raising questions about the objectivity of a massive federal study that is supposed to determine whether annual CT scans of smokers' lungs can save lives.

The nine-year study, called the National Lung Screening Trial, is tracking 50,000 smokers at a cost of $200 million, and is funded by the National Cancer Institute, or NCI. Due to be finished in 2009, the study is expected to have a major impact on whether regular CT scans for smokers will become a standard of care -- and whether tobacco companies could be forced to pay for them. The 90 million current and former smokers in the U.S. are all potential candidates for such screening.

Since late last year, the Lung Cancer Alliance, a Washington, D.C., nonprofit that supports screening, has asserted in letters to the NCI and its parent, the National Institutes of Health, that two of the study's key researchers have conflicts of interest because they have accepted money from tobacco companies to be expert defense witnesses in lawsuits. The suits sought to force the companies to pay for annual CT screening.

The Alliance, which is funded by individual donations and corporate grants, including $100,000 from General Electric Co., a maker of CT scanners, also charged the study has design flaws that could bias its outcome against screening.

There are two powerful corporate interests in this debate. On one side, there is Big Tobacco, who doesn’t want to have to pay for all of these screening CT scans in smokers, and has paid a few influential doctors who understand the downside of screening tests to argue their case. On the other side, is Big Imaging Companies, backed by hospital and physician (mainly radiologists, but others too), who stand to gain handsomely with the zillions of tests soon to be performed if CT scans are better at detecting lung masses than conventional plain-film chest x-rays.

In the middle, are the patients themselves, concerned that they might get cancer because of their genetic history or social predilection to smoke. It is the patients who will receive the seemingly innocuous scans and the invasive follow-up tests required if their scan is “positive.” What we don’t know is, does it matter to the patient’s longevity?

Now I think most doctors inherently feel that CT scans can detect smaller lung nodules compared to plain chest films.

But therein lays the problem. Once a small nodule is found, what happens? People have to know: do I have cancer? And the only definitive way to determine if they have cancer is tissue. “When tumor’s the rumor, tissue’s the issue, and cancer’s the answer – sometimes.” Certainly, positron-emission-CT scans (PET scans) can be helpful, but they are not conclusive. Tissue remains the issue.

And so, a slippery slope of additional surgical interventions (needle biopsies, bronchoscopies, mediastinoscopies, or even open thoracotomies) is required to establish if a nodule is benign or malignant. Each of these procedures has risks to the patient – some of those risks include death.

So when a sensitive, but non-specific test like a CT scan is applied to a broader population of patients, we’d better accept that, in some cases, there are untoward consequences as well as beneficial ones, and it’s the patients that deserve a controlled trial with appropriate follow-up to determine which screening test is in their best interest, irrespective of the corporate forces at play.

-Wes

Update: More on the conflicts of interest on both sides of the debate can be found at the Wall Street Journal's Health Blog.