Studying cancer incidence in 9/11 first-responders: lessons learned for future disasters

This week on the 20^th Anniversary of the 9/11 World Trade Center (WTC) disaster, we are provided with an opportunity to reflect on the lessons learned in the aftermath of this event and consider what can be done to reduce the health impacts of future disasters.

Our latest study of cancer incidence among rescue and recovery workers exposed to the WTC disaster on 9 September 2001 demonstrates the value of ongoing surveillance of chronic health effects. In the largest post-9/11 cohort of rescue and recovery workers (about 57,000) ever studied, we found the overall cancer incidence was lower than expected compared with the reference population from the New York State Cancer Registry. However, there were higher-than-expected incidences of melanoma, prostate, thyroid, and tonsil cancers. For the first time, we also found that the time when responders and rescue workers arrived on site made a difference in cancer risk: those who arrived on the day of the WTC attack had higher risk of prostate and thyroid cancers than those who arrived later in the week.

These findings reflect the work of the past two decades by a combination of policy makers, advocates, and clinical and public health scientists who made sure that important lessons learned from this disaster are not lost in the future.

What further studies are suggested by our research?

Periodic follow-up of the cohort is indicated to further characterize the long-term impacts of cancer. More in-depth evaluation of several specific cancers is ongoing, including thyroid and prostate cancers, which were recently reported. Further investigation of cancer survival is necessary to better understand the factors leading to the apparent increased cancer survival of participants in the WTC Health Monitoring and Treatment program. Additional research into the impact of increased screening on this cohort is needed, as this may clarify the factors leading to increases observed in specific screening-sensitive cancers, such as thyroid and prostate cancer.

How and where could we be studying similar types of exposures?

Historically, studies have focused on firefighters who are exposed to building collapses and fires as part of their regular work. Studies of the survivors of future natural disasters, including floods, hurricanes, and earthquakes, may be useful to evaluate the long-term effects of similar types of exposures given the increasing frequency of these types of events in the context of climate change.

Disasters involving building collapses, fires, and explosions have complex consequences that involve long-term physical and mental health aspects, in addition to the immediate effects of trauma, challenges of safe evacuation, cleanup, and economic fallout. Our studies over the past decades provide context to reflect on the health effects of the disaster 20 years after the attacks.

Starting in 2001, New York City funds, federal funds, and foundation grants supported setting up specific occupational and environmental health clinics to evaluate rescue and recover workers and survivors. These services evolved over the following decade, to create a network of periodic medical monitoring and treatment programs supported by the National Institute for Occupational Safety and Health (NIOSH). The WTC Health Registry was developed, beginning in 2002, with initial funding from the Federal Emergency Management Agency and current funding from NIOSH, to track the long-term health effects through an exposure-based cohort of over 70,000 rescue and recover workers, community members, students, teachers, children, and passers-by in Lower Manhattan on 9 September 2001.

The main physical health outcomes due to exposure to the 9/11 disaster include aerodigestive disorders, mainly chronic rhinosinusitis, gastroesophageal reflux disorder, asthma, sleep apnea, chronic obstructive pulmonary disease, and, early on, the “World Trade Center Cough.” Mental health disorders are also commonly diagnosed in this cohort, including post-traumatic stress disorder, major and atypical depressive disorders, panic disorder, and anxiety disorders, often overlapping with physical health outcomes. Studies of emerging conditions such as autoimmune disease, cardiovascular disease and cognitive impairment are ongoing and studies of reproductive outcomes and the health of children and adolescents have been published.

What can be done in the future?

Future disasters will occur, despite humanity’s best efforts to prevent them. Ensuring that the response to a disaster does not create further preventable consequences is a task that is facilitated first by preventing unnecessary exposures. For example:

• All rescue and recovery personnel must be provided with appropriate personal protective equipment and rotated frequently off-site to allow for decompression and decontamination based on the particular exposure(s).
• Electronic entry badges and personal monitoring of hazardous exposures should be provided so that personnel can be tracked and on-site hours limited.

Obviously, early on it will be difficult to provide all of the above, but effective supervision, including a zero-tolerance policy, should be instituted as soon as feasible. On-site physical and mental health screening should be considered to identify early personnel that are in danger of long-term effects. Knowing who was exposed and who is in danger of long-term effects will enable the creation of accessible, exposure-relevant, quality clinical services for those impacted, including immediate and ongoing medical monitoring and treatment. An exposure registry should be established to enable surveillance and research to determine future needs and health effects, along with referral of those who have not yet enrolled in monitoring/treatment programs, but who are reporting symptoms of potentially emerging health conditions.

We are thankful that the lessons of 9/11 will most likely not be forgotten due to the establishment of ongoing treatment and public health surveillance through the hard work of maintaining the WTC Health Program.

Featured image by Jesse Mills via Unsplash