Recently, the U.S. Preventive Services Task Force recommended the use of CT scans to screen for lung cancer in heavy smokers. Though it is controversial because it involves exposure to radiation, the recommendation is groundbreaking.
While there have long been screening tests for breast cancer, prostate cancer, cervical and other cancers, this is a first for detecting lung cancer at an early stage.
Dr. David Gandara, a lung cancer specialist at the UC Davis Comprehensive Cancer Center, explains what the recommendation means.
What is the significance of this announcement?
The reason this is so important is that it is an endorsement by the federal government for screening for lung cancer. It means the federal government has looked at all the evidence, and pooled all the information from around the world, to come up with a screening that will likely be reimbursable to the patient.
So this will end up among the free preventive services offered under the Affordable Care Act?
I think it is going to take some time, but I do expect to see that happen. And that's major news.
You've been working toward this for some time now. Why did it take the federal government so long to respond?
The federal government up until now stayed mute to calls for this screening because it was waiting for more information from foreign studies.
What kind of convincing data emerged to urge the government into action?
We've shown that, out of 50,000 people in the United States screened by CT scan for lung cancer, there was a decrease in death rates by 20 percent.
Why the attention on lung cancer?
We know lung cancer is common because, frankly, almost every family in the United States has had someone die of lung cancer. It's that common. And it's now considered a health epidemic not only in the United States but worldwide.
These are cancers directly linked to smoking?
In my patients here in the Comprehensive Cancer Center, about a third have never smoked. We are somewhat sequestered from the brunt of tobacco-based lung cancer because so many people in Northern California are either "never smokers" or they quit smoking long ago.
What is a "never smoker," and why does that term matter?
The definition of a "never smoker" is somebody who has smoked fewer than 100 cigarettes in their life. If you've smoked more than 100 but quit, you are called a "former light smoker."
But that's not the population this recommendation will affect?
The recommendations in these guidelines are for pretty heavy smokers – what we call smokers with "30 pack years." That can be someone who has smoked a pack a day for 30 years or someone who has smoked two packs a day for 15 years. And if you smoked half a pack a day for a very, very long time, you might come under this definition. At any rate, that's the group that you can show a decrease in mortality rates with CT scans between the ages of 55 and 79.
What's controversial about this recommendation?
One thing that people are concerned about is that this could somehow encourage someone to smoke, but I don't think that's the right message. This is not a magic bullet. Everyone who smokes, of course, should go into a smoking cessation program. But this is hopeful. I was surprised there was such a great decrease in mortality in the national lung screening trial. Twenty percent – that's pretty impressive.
Do you get a sense of whether more young people are smoking these days?
That's what I observe and what I've been told by patient advocate groups. There's the sense that, especially for teenagers and especially for teenage girls, there actually is a big boost in the percentage who are smoking now compared to 10 years ago.
What other screening methods beyond the CT scan might become useful for catching lung cancer early?
There's research being done in Northern California to try to find a blood test to detect early stages of lung cancer. We have a grant from the Department of Defense for which I'm the principal investigator here. This allows us to try to develop new blood biomarkers that can lead to early detection.
Can you talk a little more about that?
Every one of us has some free DNA coursing through our blood. We know that cancer patients tend to have three or four times that amount. Cancer cells turn over just like normal cells – they die and that DNA gets put into the blood. So if you were a patient with a cancer mutation in your blood, a sensitive test might be able to find it.
What happens if you are a longtime smoker and you have a CT scan that finds something abnormal?
Now, if a patient has a scan and there is an abnormality, there needs to be a determination made by a team of radiologists, pulmonologists, surgeons and medical oncologists like myself. We evaluate the CT scan to make sure what shows up is not previous scarring from an old pneumonia or something benign. We want to make sure there are no unnecessary biopsies because there can be complications from biopsies. So if the risk is not very high, maybe we would say, "Let's just follow this up with another scan six months from now."
What impact will this have on public health in the United States as a nation?
This is an area that's being debated right now. Is this a cost-effective way of improving survival for lung cancer? It's been estimated by some that if everybody who is in this risk category went out and got a CT scan that it could cost a billion dollars. That sounds like a lot of money. In the long run, though, if the CT scans mean we can catch lung cancers at Stage 1, and they are curable, that will save the nation a lot of money. So to me, the balance is in favor of doing the screening.