Many Lung Cancer Tumors May Prove Harmless
Research suggests CT scan screening might lead to needless worry, treatment in these cases
Patz characterized his findings as "one piece of information they were waiting for just to understand the risks and limitations of the trial and of recommending mass screening."
"When we tell patients we're going to do a test, you need to understand the risks and benefits," he said. "This is just part of the equation."
Edelman said some of the over-diagnosis can be attributed to slow-growing tumors. In other cases, however, smokers will not die of cancer because they will succumb first to emphysema, heart disease or the myriad of other major health problems caused by smoking.
"It could be that heavy smokers die of lots of other things before the cancer can kill them," Edelman said.
Patz and Dr. Otis Brawley, the American Cancer Society's chief medical officer, said the results highlight the need for future research to uncover genetic markers that will allow doctors to better sort aggressive cancers from cancers that might not need to be treated.
Brawley added, however, that the presence of over-diagnosis does not change the fact that CT screening can save thousands of lives a year.
Calling the original trial "one of the greatest screening studies ever done," Brawley said the clinical trial had successfully detected two types of lung cancers -- the 80 percent that could not be cured and the 20 percent that could be successfully treated.
"Now we're realizing there's a third kind of cancer -- the kind that doesn't need to be cured but can be cured," Brawley said. "We cure some people who don't need to be cured, but the study clearly shows by treating everyone we cure people who need to be cured."