Increase in Some Cancers Among 9/11 Rescue Workers

Megan Brooks

December 18, 2012

A study of rescue and recovery workers involved in the World Trade Center (WTC) atrocity in September 2011 has found small increases in rates of prostate and thyroid cancers and multiple myeloma beginning 6 years after 9/11.

There were no increases in cancer overall (all sites combined), the researchers report in their study, which was published in the December 19 issue of JAMA. It is not clear how medical screening and non-WTC risk factors contributed to the increases in prostate and thyroid cancers and multiple myeloma, they note.

Dr. Steven Stellman

"Because of the long latency periods for many cancers, this is still a very early study," researcher Steven D. Stellman, PhD, MPH, from the Mailman School of Public Health at Columbia University in New York City, explained in an email to Medscape Medical News.

"Given the relatively short follow-up time and lack of data on medical screening and other risk factors, the increase in prostate and thyroid cancers and multiple myeloma should be interpreted with caution," he and his colleagues note.

"The etiological role of WTC exposures in these 3 cancers is unclear. Longer follow-up of rescue/recovery workers and participants not involved in rescue/recovery is needed with attention to selected cancer sites and to examine risk for cancers with typically long latency periods," they add.

The WTC Health Registry

The study involved 55,778 residents of New York State who were enrolled in the WTC Health Registry in 2003/04; 21,850 were rescue/recovery workers and 33,928 were not involved in 9/11 rescue/recovery. All participants were followed from enrollment until December 2008.

The researchers identified cancer cases through linkages with 11 state cancer registries. They computed standardized incidence ratios (SIRs), adjusted for age, race/ethnicity, and sex, and used New York State rates from 2003 to 2008 as the reference. They focused on cancers diagnosed in 2007/08 because these are "most likely to be related to exposure during September 11 and its aftermath," the researchers write.

By December 31, 2008, 1187 new cancers had been reported in the study population (n = 55,778). Of these, 439 cancers (37%) were diagnosed in rescue/recovery workers and 748 (63%) were diagnosed in those not involved in rescue/recovery. The median age at cancer diagnosis was 57 years.

For all 23 cancer sites combined, cancer incidence was not significantly different from that in the reference population during either the early period (up to 2006) or the later period (2007/08).

However, among rescue/recovery workers, the SIRs had significantly increased by 2007/08 for 3 cancers; for prostate cancer, the SIR was 1.43 (95% confidence interval [CI], 1.11 to 1.82); for thyroid cancer, it was 2.02 (95% CI, 1.07 to 3.45); and for multiple myeloma, it was 2.85 (95% CI, 1.15 to 5.88).

Mirror Results

For those not involved in rescue/recovery, there was no increase in incidence in 2007/08, the researchers report. "Using within-cohort comparisons, the intensity of World Trade Center exposure was not significantly associated with cancer of the lung, prostate, thyroid, non-Hodgkin lymphoma, or hematological cancer in either group," they add.

Dr. Stellman told Medscape Medical News that this study and an earlier study (Lancet. 2011;378:898-905) of New York City firefighters "reached similar conclusions about increases in the rates of prostate and thyroid cancers among WTC-exposed rescue and recovery workers, despite the fact that the 2 studies differed in many respects, including the diversity and types of exposed populations studied, the comparison populations, and the methods used."

He noted that the previous study looked only at male firefighters, whereas this WTC Health Registry study involved male and female firefighters, police, sanitation, construction, and other rescue and recovery workers.

"The Registry plans to continue confirming cancer diagnoses among enrollees with state cancer registries to monitor longer-term trends," Dr. Stellman said.

The study was supported by the National Institute for Occupational Safety and Health and the Agency for Toxic Substances and Disease Registry, which included support from the National Center for Environmental Health of the Centers for Disease Control and Prevention, and the New York City Department of Health and Mental Hygiene. The authors have disclosed no relevant financial relationships.

JAMA. 2012;308(23):2479-2488. Abstract