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How Biostatistics Led to National 9/11 Cancer Proposal

It is rare in the career of a medical researcher that his or her work makes a big difference. Most advances are small and incremental. But on infrequent occasions, the work of an individual or a group of individuals can change clinical practice or public policy. This is one of those instances.

On June 8, 2012, after considerable study and debate, the National Institute of Occupational Safety and Health (NIOSH) proposed covering 50 types of cancer possibly related to the 9/11 attacks, with treatment covered by the Zadroga Act. The act is named after James Zadroga, an NYPD officer who died in 2006 from respiratory disease attributed to rescue and recovery operations at Ground Zero.

Since 2005, I have been the lead statistician for the World Trade Center Medical Monitoring Program of the Fire Department of the City of New York(FDNY).

In my career, I have been primary or co-author on 98 peer-reviewed publications. But none has had the impact of a September 2011 Lancet study published in collaboration with efforts from the FDNY, Albert Einstein College of Medicine and Montefiore Medical Center, the University Hospital and academic medical center for Einstein. The study showed that New York City firefighters exposed to toxins from the 9/11World Trade Center attack were nearly 20 percent more likely to develop cancer than their unexposed colleagues in the seven years after the attack.

I am proud to say that my efforts played a role in this NIOSH decision, which the institute’s  director, Dr. John Howard, says was influenced by the findings of our research published in Lancet. (See related video.)

In the study of nearly 9,900 firefighters, we examined the incidence of cancer among those who had been exposed to the rescue/recovery/cleanup effort after the terrorist attack that destroyed the two World Trade Center towers on September 11, 2001, and compared that with the exposed firefighters’ own cancer-incidence experience prior to then (which the FDNY had in its pre-9/11 monitoring database). The incidence of cancer in the exposed firefighters was also compared with that of unexposed firefighters over the first seven years after the attack. Unexpectedly, we found a modest exposure effect, as noted above.

There was great skepticism when we started this work. Conventional wisdom holds that it should take decades before a cancer effect is discernible. However, exceptions are known to occur, such as the increased rates of thyroid cancer soon after radiation exposure (Chernobyl) and hematologic cancers after exposure to polyaromatic hydrocarbons.

We shared this concern, but understood that this was a critical public health issue for those exposed. In science, we must sometimes make difficult decisions based on limited data; by the time we could conclusively prove the association between 9/11 exposure and cancer, it might have been too late for the people who need treatment now. So we designed our analyses to be as complete and as free of bias as is possible in an observational study. We were careful to correct for possible biases and consistently chose the more conservative approach when faced with alternatives.

Our team was committed simply to examining the data and reporting the results. Time will tell whether our results are confirmed by researchers studying other World Trade Center–exposed cohorts and whether cancer rates will remain the same, increase or decrease. At present I am pleased that our work has had an impact and that medical care will be provided to the 9/11 responders.

As with most good science, an ambitious and talented team was behind this effort. I want to thank all those who made this work possible, particularly Rachel Zeig-Owens, the first author on the paper, who is still a graduate student in epidemiology at the City University of New York. She did most of the work and appears headed for a great career. I also want to congratulate Dr. Mayris Webber, senior epidemiologist at the FDNY, for her commitment to solid research, and Dr. David Prezant, program director, an Einstein faculty member and a Montefiore clinician, for his total dedication to the project. And I want also to thank Dr. Thomas Rohan, my department chair, for his unwavering support.

It’s gratifying to see the results of a statistical analysis have the potential to save lives or at least improve the quality of life for so many.

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