Surviving Lung Cancer

New tests may help doctors find lung cancer at earlier stages

by Dr. Barry Starr, Stanford University

Cancer is a terrible disease to get. And lung cancer in one of the worst.

Not only do some people feel guilty if smoking was involved, but people with lung cancer do not do well. Around 80-85% of people diagnosed with lung cancer die within five years.

Why is this? One idea is that it is because doctors can't find lung cancers early, before they spread. And once a cancer spreads, it is very hard to treat.

So one way to help lung cancer patients might be to come up with tests that find their lung cancer earlier. Two recent studies explore completely different ways to do this.

The first study takes advantage of the fact that cigarette smoke damages more than lung cells. And the second looks at the chemicals in a patient's breath.

Collateral damage

As I said, lung cancer is usually found late. This is because there often aren't many symptoms until it has spread. And it is very hard to get a hold of a lung cell to look at directly.

Scientists decided to see if there were other cells to look at. Blood tests are a pretty noninvasive way to look for cancer. But there aren't any blood tests available to find this kind of cancer.

What about upper airway cells? These cells aren't trivial to get but they are way easier than lung cells. And scientists do know that cigarette smoke damages these cells.

If these airway cells are changed by cigarette smoke the same way in all lung cancer patients, then looking at these cells might help find people with lung cancer. And this is just what a group of scientists may have discovered.

Microarrays can be used
to find lung cancer early.

What they did was look at how the DNA was being used in airway cells that had been abused by cigarette smoke. They found that the airway cells of smokers with lung cancer tended to use their DNA in a way different than usual. And from that, they were able to find people with early stage lung cancer 90% of the time.

How'd they do it? Using microarrays, they looked at over 14,000 genes in the airway cells of 77 smokers suspected of having lung cancer. (Microarrays are just a way to look at thousands of different genes at once.)

The scientists found around 80 genes that behaved the same in these patients. Next they checked to see how these genes behaved in 87 completely different patients. The researchers found that by looking at these genes, they were able to detect early stage lung cancer 90% of the time.

The test is an interesting one because it gets to the heart of how cancer works. Cancer happens when DNA damage makes cells use its genes differently. And cigarette smoke does massive damage to DNA.

Of course not all DNA damage leads to cancer. Which is why not everyone who smokes gets lung cancer. No, the damage has to happen in certain spots.

These places on the DNA tend to be ones that affect certain genes. Often these are genes that control when a cell divides or how good it is at fixing DNA mistakes.

When these genes are damaged, the cell grows uncontrollably and spreads. Smoking is so risky because cigarette smoke causes so much DNA damage.

Because of how cancer works, the future of tests that look at how DNA is used looks bright. A similar test was recently approved by the FDA for use with breast cancer. And now this lung cancer test is moving along nicely. Who knows which cancer will be next?

More Information

• Airway epithelial gene expression in the diagnostic evaluation of smokers with suspect lung cancer

The smell of cancer

A dog can smell cancer
on your breath.

Of course that test requires that airway cells be harvested from the patient. Not the most pleasant experience in the world!

Wouldn't it be cool if there was an easier way? Well, some scientists are hopefully on their way to developing one. A breathalyzer for cancer.

Apparently lung cells let off certain chemicals into our breath. Sort of like the scent of a lung cell.

And lung cancer cells let off different compounds. Of course, we can't tell the difference in smell. But there are ways to tell if these compounds are in someone's breath.

One way is with a trained dog. It has been reported that a trained dog can detect lung cancer 99% of the time!

Of course, having a dog sniffing for cancer in the doctor's office is not ideal. So one group of scientists is working on a filter test that can find out if a patient has lung cancer by looking at the patient's breath.

Basically a patient breathes on a filter with 36 different chemicals spotted on it. Depending on what is in the patient's breath, some or all of the spots change to different colors. The idea is that a certain pattern of colored dots means lung cancer.

They tested this on 143 people. There were 21 healthy volunteers and 122 people with various lung problems including cancer. The test found the people with lung cancer about 75% of the time.

Now this test isn't ready for prime time yet. An accuracy rate of 75% is just too low. But maybe in 5 or 10 years we'll be breathing into a dog's face or onto a filter to see if we have lung cancer.

More Information

Content provided by the Department of Genetics, Stanford University.