Study: No higher overall cancer rate in 9/11 responders

While rescue and recovery workers exposed to dust and debris at the World Trade Center site after the Sept. 11 terrorist attacks may have higher rates of some cancers, the overall incidence rate between workers and the general population is the same, a study released Tuesday has found.

The study, published in the Journal of the American Medical Association, suggests possible links with prostate, thyroid and a type of blood cancer among rescue and recovery workers exposed to toxic debris from the terrorist attacks.

The research didn't find an increase in the total number of cancers among workers or a higher risk among others exposed to the aftermath of the 2001 attack, such as those living in the area.

The study involved nearly 56,000 people enrolled in a registry set up to monitor health effects in those exposed to the aftermath of the trade center attacks. Most participants volunteered for enrollment, which could skew the results if people who already had symptoms were more likely to enroll than healthier people.

Cancers diagnosed through 2008 were included in the study, but that's just seven years after the 2001 attacks, and cancer often takes longer to develop. People diagnosed with cancer before the attacks were excluded from the study.

Cancer rates were compared with those in the general New York State population. But the researchers had no data on whether people in the study had risk factors for getting cancer, including a strong family history, or if they had existing cancer that wasn't detected until after the disaster. Participants are being monitored for health issues and may have gotten more cancer screening than other people, which also could skew the results.

The study comes just a few months after the federal government added dozens of types of cancer to a list of illnesses related to the trade center attacks that will be covered by a program to pay for health coverage.

The study results "won't settle the question because it's still too early," said Dr. Thomas Farley, New York City's health commissioner. "People are very, very interested in this topic and we thought it was important to get the data out that we have even though it is early."

Researchers from the city's health department led the study, which was partly paid for by the National Institute for Occupational Safety and Health. NIOSH spokesman Fred Blosser said the agency welcomes the results and that longer follow-up is needed to examine risks for cancers that take a long time to develop.

In the new study, possible links were mainly seen with cancers diagnosed in 2007 and 2008 in rescue and recovery workers. These included 67 cases of prostate cancer, 13 thyroid cancer cases and seven cases of multiple myeloma -- all at rates higher than in the New York State population.

Donald Berry, a biostatistics professor at the University of Texas M.D. Anderson Cancer Center in Houston, said the study has too many limitations to draw any definitive conclusions.

"There's no evidence that 9/11 caused any of these cancers," Berry said.