NEW YORK (Reuters Health) - Rescue and recovery workers who provided aid after the World Trade Center attacks may have an increased risk of certain types of cancer, including prostate and thyroid cancers, a new study suggests.
However, that finding was based on a relatively small number of cancers. And neither relief workers nor people who lived, worked or went to school near the towers had a higher-than-average chance of being diagnosed with all cancers combined up to seven years later.
"There's a lot of interest in the question of, does exposure to the World Trade Center cause cancer?" said Dr. Thomas Farley, the New York City Health Commissioner.
In part, that interest has been driven by a debate on whose health care should be covered by the James L. Zadroga 9/11 Health & Compensation Act - set up to care for World Trade Center victims - and what conditions should be included.
Based on this study, Farley said the role of the attacks on cancer risk is "complicated."
"Most of the people who have had cancer so far would have had it anyway," Farley told Reuters Health.
But because cancer can take 20 or more years to develop, the true risks may not become clear for many years, he added.
Researchers have predicted that exposure to dust, smoke and other chemicals after the 9/11 World Trade Center attacks may have put people who were nearby or involved in the clean-up efforts at risk of some diseases, including cancer.
To see how those workers and residents had fared through 2008, the New York City Department of Health and Mental Hygiene tracked 55,778 enrolled in the World Trade Center Health Registry. That included 21,850 people involved in the rescue and recovery efforts.
Using state cancer records, the research team, led by Jiehui Li, recorded any new diagnoses among those groups and compared their chance of cancer to data from all of New York State during the same time period.
In total, there were 1,187 new cancers among everyone in the health registry. The overall rates for both rescue workers and residents were similar to the rate of cancer diagnoses across the state.
Out of 23 types of cancer the researchers examined, three cancers were more common in rescue and recovery workers during the last two years of the study: prostate cancer, thyroid cancer and multiple myeloma - cancer of the bone marrow cells.
Aid workers were between 1.4 and 2.9 times more likely to be diagnosed with one of those cancers in 2007 or 2008 than other New Yorkers, the researchers reported Tuesday in the Journal of the American Medical Association.
That was based on 67 prostate cancers, 13 thyroid cancers and seven myelomas among responders.
TIME WILL TELL
Dr. Jacqueline Moline from North Shore-LIJ Health System in Great Neck, New York, said studies have consistently shown a higher rate of thyroid cancer in responders - but it's unclear why rescue workers would also be at increased risk of prostate cancer.
Farley said it could be that people who were exposed have had better health care in recent years, so they've been checked for prostate and thyroid cancer more often.
"It may be that these would be cancers that would never have been picked up" had workers not been screened, he said.
Moline, who has studied cancer in World Trade Center responders but wasn't involved in the new report, also noted that seven years isn't a very long time to track the growth of solid tumors.
"I think as times goes on we are going to see increased rates of cancer in those who were exposed, at higher rates than we would expect if they weren't exposed," she told Reuters Health.
Researchers should especially be on the lookout for whether certain cancers show up earlier than usual, or in unexpected populations - for example if lots of non-smokers are diagnosed with lung cancer, Moline said.
"We don't have a really good handle on what happens when people are exposed to a complex mixture of carcinogens," she added.
"I think we're not going to get a full answer for many years."
That's a concern, Moline said, because the Zadroga Act only provides health monitoring and care for people affected by the attacks through 2016 - before some related cancers may have even been diagnosed.
Farley said the major health risks linked to the World Trade Center attacks so far have been breathing problems such as asthma and mental health problems, including post traumatic stress disorder. But he said he and his colleagues will continue to monitor cancer in relief workers and residents.
SOURCE: bit.ly/JjFzqx Journal of the American Medical Association, online December 18, 2012.