Saving a Life. A Simple CT Scan Away

How the NLST has found a breakthrough method to screen for lung cancer, and how it may save millions of lives. 

The National Lung Cancer Screening Trial (NLST) was a study performed by the National Cancer Institute to evaluate the efficacy of using CT scanning in the prevention and detection of lung cancer. In other words, it was trying to determine if medical x-ray imaging could be used to find lung cancer before symptoms even arose in patients. On November 4, 2010, before the trail was even complete, they revealed to the public a resounding "it works!". Now, why on earth is this so important, and more importantly why should you care?

No one needs to be informed that cancer is a petty, ugly disease, but you'll be surprised to know some basic facts about lung cancer specifically that might have skipped your attention. In this past year in the United States alone, a whopping 222,520 people will be diagnosed with lung cancer and of those 157,300 will die with the disease, that's more than 70% for those not keeping track. The large percentage of lung cancer diagnoses and deaths were (you guessed it) related to smoking or second-hand smoke exposure; 85-90% of the diagnoses were related to smoking in some way. The simple message here that's been drilled into your head so many times is that smoking is bad for you, stop it!

Now, the NLST tested more than 53,000 patients at risk for lung cancer development (that is, heavy smokers). The screening method they used is what's known as a helical computed tomography scanner (hCT). That mouthful of terms is a fancy new CT scanning method that can continuously scan a patient as they travel through the scanner. As the patient travels through the donut-shaped-hole in the machine, the spinning x-ray tube traverses a corkscrew pathway around you and makes digital slices of your insides, these are then examined by a radiologist for disease clues. This new method translates to faster scan times (as low as 15 seconds) and improved visualization of anatomical structures.

What the trial discovered was that 20 percent fewer lung cancer deaths were associated with the screening method, and 7 percent fewer deaths in general (from any disease) were associated with the use of CT scanning compared with the use of standard chest x-rays. The results, to be published sometime in the near future, indicate that those with a high risk for developing lung cancer (again, smokers) could definitely benefit from screening with low-dose hCT.

Current screening methods for lung cancer usually cannot detect it until it has spread to other parts of the body and causes symptoms, by that point it may be too late to treat. The lack of treatment success combined with inadequate methods of early detection are what make lung cancer such a large killer. This new discovery will essentially do for lung cancer what the colonoscopy procedure did for colorectal cancer, or the mammography did for breast cancer: improve survival rates! In the battle against cancer, this is another step (albeit a very large step) in combating a disease that touches everyone at some point in their lives, whether directly or not.

On a personal aside, being in the medical physics field, I can't help but marvel at how much of an impact a simple screening process by an x-ray machine could turn around survival rates for a particular disease. To me it seems that medical imaging and radiation medicine in general are slowly achieving for cancer what vaccinations effectively achieved for communicable diseases, prevention or eradication. The field is not there yet, not by a longshot, but hopefully that is where it will end up in the future. As always, I remain painfully optimistic.

References:
The original story by the NCI can be found here, and the complete version here

Young PR, et al (2009). COPD prevalence is increased in lung cancer..Euro Res J;34(2):380-386.