CT Screening for Lung Cancer
Musicians' Assistance Program
Volume CI, No. 7/8July, 2001
If you are a smoker or were a smoker in the past, and are age 60 or over, you can now receive chest CT screening free of charge through a research study being conducted at Columbia-Presbyterian Medical Center. If interested, you can call Dr. John H. M. Austin, Director of Thoracic Radiology at the Columbia-Presbyterian Medical Center, at (212) 305-6849, to set up an appointment.
How could this be an important opportunity for you? Researchers are saying that a painless, 20-second test known as low-dose CT (the full name is “low radiation dose computed tomography”) can find lung tumors long before they appear on traditional chest x-rays. The test entails only slightly more radiation than a chest x-ray. The usual cost of this diagnostic test is about $300 to $500. Follow-up tests may be necessary to track suspicious nodules, in order to avoid unnecessary biopsies. Any follow-up tests are covered by usual medical insurance, if a nodule or other abnormality is being followed.
The study includes a no-cost follow-up low-dose chest CT scan one year later. It also includes collection of blood, urine and cells from inside the mouth (which are obtained simply by using a toothbrush) for genetic studies, looking at the body’s DNA from the point of view of risk for cancer. This is a sophisticated study from a laboratory point of view – and the researchers believe the volunteers will make a very important contribution to knowledge about cancer.
Regarding the expected outcome of participation in the study, Austin states, “I expect that an estimated 2 to 4 percent of smokers or ex-smokers in their 60s or 70s receiving this test will have an early lung cancer, and a high likelihood that the early detection will allow cure. People should also know, however, that if the scan shows something, the chances are still about 90 percent that what it shows is not a cancer – and they will have to be willing to let time pass and get a follow-up scan later to show that the finding, which is usually a little scar, is unchanged.”
Lung cancer is the leading cause of cancer mortality in the United States in both men and women. This year more than 160,000 Americans will die from this disease, which is usually diagnosed only after it has advanced too far to be stopped. Currently, more than eight out of every ten cases of lung cancer are not diagnosed until after the cancer has metastasized. The five-year survival rate has increased very little in the last 30 years.
Some researchers believe that CT screening will transform the prognosis for lung cancer, just as mammography did for breast cancer and the PAP test did for cervical cancer. Lung cancer tumors are typically about the size of an orange by the time they are discovered. By contrast, most of the lesions detected on CT are about the size of a pea.
While the current five-year survival rate for lung cancer is only 14 percent, it could increase to 80 percent if all smokers and ex-smokers received annual CT exams and early treatment, according to an article by Claudia Henschke, M.D., Ph.D., principal investigator of the CT study and Chief of Chest Imaging at the New York Weill Cornell Center of New York Presbyterian Hospital, in the July 10, 1999, issue of The Lancet, a prestigious British medical journal.
The Early Lung Cancer Action Project’s (ELCAP) clinical trial used a group of 1,000 symptom-free volunteers who were at least 60 years old and had smoked the equivalent of a pack of cigarettes a day for 10 years. The ELCAP research team conducted both low-dose CT exams and chest radiographs, and compared the results. Using the low-dose CT, the ELCAP research team diagnosed 27 cancers – compared to seven using chest radiography. Twenty-three of the 27 cancers identified with CT proved to be stage I malignant disease, and 26 were capable of being treated surgically.
Another study at the Mayo Clinic in Rochester, Minn., substantiated the ELCAP findings. It concluded, after examining 12,300 subjects, that CT screening is ten times more likely to detect malignant lung disease than is chest radiography. Eighty percent of the lung cancers uncovered were in stage IA disease, which is very early in the progression of the disease.
The down side to low-dose CT scans is that at least one out of five people have small scars in their lungs from old, healed infection and need to return, usually after six months, for a follow-up scan. A scar will show no change – as opposed to a cancer, which can be expected to grow. These patients could be subjected to unnecessary follow-up imaging and biopsies. However, researchers believe that CT techniques can be expected to become more accurate.
Long-term follow-up assessing the cure rate and cost of testing is necessary before a national screening program will be recommended. Also, although it is highly probable that low-dose CT screening for early lung cancer will save lives, it has not yet been proven that early diagnosis will increase survival. To date, the only country where screening for lung cancer has become generally accepted is Japan.
Insurance companies do not yet cover this screening, as they feel there is inadequate evidence in the medical literature that mass lung cancer screening using low-dose CT scans will contribute substantially to the detection of smaller cancers, or decrease mortality.
And since low-dose CT scans are still in the trial phase, the American Cancer Society and other public health organizations does not yet recommend the screening. Henschke and her supporters fear that hundreds of thousands of people will die of lung cancer before the diagnostic power of low-dose CT screening is demonstrated definitively.
The following were source material for this article:
- Interview with Dr. John H.M. Austin, Director of Thoracic Radiology at the Columbia-Presbyterian Medical Center
- “Low-Dose CT” by James Brice in Diagnostic Imaging, May 2000
- “Screening for Lung Cancer: Time to Think Positive” by Ian E. Smith in The Lancet, Vol. 354, July 10, 1999
- “Early Lung Cancer Action Project: Overall Design and Findings from Baseline Screening” by Henschke C., et al, in http://www.journalclub.org/vol2/a71.html
- “The American College of Radiology Statement on Total Body CT Screening” in http://www.acr.org/departments/pub_rel/press_releases/total-bodyCT.html
- “American Lung Association Statement on New CT Screening Technique for Lung Cancer, July 29, 1999, in http://www.lungusa.org/press/association/asnctlung.html
- “Low-Dose Spiral CT Screening for Lung Cancer” in http://www.mayo.edu/research/pcrc/trial_80.html
- “New York Weill Cornell Researchers Report CT Screening of Patients at Risk for Lung Cancer Saves Lives” in http://www.ny-cornell.org/news/press/1999/ctscan.html.