"What we're finding with CT screening are more early-stage cancers. That could be good news--finding cancers that we'd otherwise find at a late stage," said the study's lead author, Stephen J. Swensen, M.D., professor and chair of the Department of Radiology at Mayo Clinic in Rochester, Minn. "However, a number of these are probably non-lethal or slow-growing cancers that the patient would likely have died with and not from. Other cancers were so aggressive that early detection with CT did not make a difference."
Lung cancer is the leading cause of cancer death in both men and women in the United States, killing more people than breast, prostate and colon cancers combined, according to the American Cancer Society (ACS). ACS estimates that in 2005 there will be approximately 172,570 new cases of lung cancer diagnosed in the United States and 163,510 people will die from the disease.
While recent studies have focused on the benefits of early detection, the Mayo researchers looked more closely at the negative impact of CT screening, including over-diagnosis, expense, changes to quality of life, unnecessary surgical procedures and mortality. The study, funded in part by the National Cancer Institute, represents the most complete follow-up of the same group of patients of any published CT lung screening research.
Between January 1999 and May 2004, Dr. Swensen and colleagues studied 1,520 current and former smokers at high risk for lung cancer. The patient group contained 788 men and 732 women, age 50 or older (median age 59). All patients received an initial low-dose, helical CT examination, with annual screenings over the next four years.