9/11 study on cancer risk may be premature.

nonexposed colleagues, and that uncorrected number was statistically signifi cant. Elevated rates emerged for prostate and thyroid cancer, melanoma, non-Hodgkins lymphoma, multiple myeloma, and leukemia. With the prevalence of cancer in the general population, at least some of the increases were probably an artifact of the intensifi ed screenings that 9/11 fi rst responders in the study received. Screening can turn up tumors that may remain undetected and subclinical in nonscreened groups, the researchers said. Most fi refi ghters who worked at the site were enrolled in an ongoing health monitoring program and receive comprehensive blood screening every 12 – 18 months. That may help account for the 21% increase in prostate cancer among the exposed fi refi ghters compared with the general population. The exposed group also receives routine chest x-rays and follow-up CT scans if they have asthma or other respiratory ailments, which were the major health problems documented among the police and fi refi ghters in the wake of 9/11. More than two-thirds of fi rst responders reported new or worsened breathing problems, according to a December 2006 study in Environmental Health Perspec tives , and the disproportionate number of CT scans given to that group may have detected the increases in thyroid cancers and lymphoma that the study found.