November 9, 2006

Prof Uses CAT Scan To Find Lung Cancer

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Out of a pool of approximately 31,000 smokers and ex-smokers screened using the computed tomography technology (commonly referred to as CAT or CT scans), 484 patients were diagnosed with lung cancer. 85% of them were at Stage I, a stage at which the cancer can still be treated successfully. Without the CT technology, lung cancers are usually detected later on when the treatment is not nearly as effective.

Such were some of the results that Prof. Claudia Henschke, radiology, and her colleagues arrived at in their research on the lung cancer detection.
The studies have been published in such prominent medical publications as The Lancet and, at the end of October, The New England Journal of Medicine.

Henschke became interested in the topic in the beginning of the ’90s when it became possible to acquire multiple body images in a single breath. She put together a multidisciplinary team of scientists and doctors that started discussing the techniques for early lung cancer detection.

Subsequently, The International Early Lung Cancer Action Program was formed. Currently, the program holds biannual conferences that focus on the pressing issues in the field of early lung cancer detection and treatment.

According to Henschke, 1999 marked international community’s heightened interest in lung cancer screening. Since then, she has been one of the most prominent advocates of administering routine CT scans to smokers and former smokers. Prof. Gordon Gamsu, radiology, suggested that about 85% of all lung cancer occurrences are due to smoking.

“Dr. Henschke is a very good research worker. What she has brought to light is an incredibly important expansion of our knowledge of lung cancer,” he said.

At the same time, Gamsu said, the smoking population in the United States is dropping rapidly, and, while lung cancer is certainly a major issue today, in fifteen years time it will likely become an uncommon disease.

Henschke said that in addition to the CT screening, smoking cessation advice is given to all of those who are still smoking at the time they undergo the procedure.

Henschke’s studies are conducted using a novel design that partitions the screening study into its two component parts: first step is to diagnose the cancer, and those who are diagnosed are then treated. According to Henschke, randomization can be done at the time of the treatment decision, when the patients can be offered either immediate or delayed treatment. As far as the diagnostic tests go, she said it would be unethical to offer simple chest X-rays to one group, as her earlier study showed that 83% of the Stage I cancers are missed on chest X-ray, while the clearly more effective CT scans are given to the other group. If this were the case, the former group would be at a clear disadvantage by not being screened using the more advanced technology.

Moreover, it has been argued that CT scans, which pick up both malignant and benign tumors, might raise false alarms and lead the patients to undergo unnecessary and risky surgeries.

This, according to Douglas Ballon, is the general question that has been raised by the community and by the non-specialists in the field.

“The efficacy and the accuracy of [CT tests] has not been proven; you don’t want to open up a floodgate and have all kinds of tests done,” he said, reflecting upon the public opinion. “But as long as you say exactly how you did the study, then it can be judged by the community as to what’s to accept.”

According to Gamsu, exposure to small amounts of radiation during routine CT screening is another risk that has to be factored into the studies. “It’s not like a little blood test — [CT screening] uses a lot of radiation, a lot of cost and no recognized, at this stage, benefits.”

Although CT screening would detect many small lesions that subsequently would be removed, it remains unclear if the lesions that would be operated on were really cancer in the first place.

Gamsu suggested that although CT scanning does pick up a lot of lesions that may not be seen in X-rays, further research must be done in order to properly evaluate the trade-offs present in this controversial procedure.