Study shows World Trade Center-exposed NYC firefighters are 19% more likely to have cancer than

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Study shows World Trade Center-exposed NYC firefighters are 19% more likely to have cancer than
By Lancet, Sep 1, 2011 - 4:00:00 AM

A study published in this week's 9/11 Special Issue of The Lancet shows that a higher proportion of World Trade Center-exposed New York City male fighters have been diagnosed with cancer compared to both their non-exposed colleagues and a comparable sample of the New York City general population. 263 cases of cancer occurred compared with 238 expected from the general population data. In the non-exposed group, 135 cancers were diagnosed compared with 161 expected from the general population. The findings are reported in an Article by Dr. David J. Prezant, Chief Medical Officer, Fire Department of the City of New York (FDNY), USA, colleagues from FDNY and Albert Einstein College of Medicine of Yeshiva University and Montefiore Medical Center, Bronx, NY, USA.

The study involved 9853 male firefighters, all of whom had health records dating back to well before 9/11. The authors looked at cancer incidence and its potential association with exposure in the first 7 years after 9/11. They compared the cancer incidence rates in WTC-exposed firefighters with cancer incidence in non-exposed firefighters, adjusted for age, race and ethnic origin, and secular trends, and with the US National Cancer Institute Surveillance Epidemiology and End Results (SEER) reference population.

The authors excluded data from 576 firefighters out of the 10000+ original study population who would have been aged 60 years or older on September 11, 2001, because their small number could have generated statistically unstable age-adjusted rates. For the same reasons, they excluded data from 32 women, 13 Asians, and 8 Native Americans. Finally, they excluded 85 individuals who had a cancer diagnosis before 1996*,resulting in a final cohort of 9853 non-Hispanic white (94%), non-Hispanic black (3%), and Hispanic (3%) male firefighters, who had a mean age of 44 years on 11 September 2001.

In the WTC-exposed group, 263 cases of cancer occurred compared with 238 expected from the general population data. In the non-exposed group, 135 cases occurred compared with 161 expected from the general population. When cancer incidence in the WTC-exposed FDNY firefighters was compared with the cancer incidence in the general male population in the USA with a similar demographic mix (using standardised incidence rations [SIR]), WTC-exposed FDNY firefighters were at 10 percent increased risk of having any cancer. When the cancer incidence in WTC-exposed FDNY firefighters was compared with WTC-non-exposed FDNY firefighters, the increased cancer risk (adjusted for surveillance bias) for exposed firefighters was 19 percent. That the non-exposed firefighters had lower cancer rates than the general population is no surprise, and is likely due to the healthy worker effect: FDNY firefighters have lower smoking rates, stringent pre-employment health requirements, and greater physical fitness standards than the general population.

The cancer incidence for WTC firefighters at specific sites in the body was not significantly increased when compared to site-specific cancers among non-exposed firefighters and the general male population. This failure to reach statistical significance may have been due to small sample size. A trend towards increased risk was, however, noted in 10 of the 15 sites studied (stomach, colon, melanoma, prostate, thyroid, non-Hodgkin lymphoma, bladder, kidney, pancreas, oesophagus). Surprisingly, however, the authors noted 58% lower rates of lung cancer in WTC exposed participants than in the general population, and there appeared to be no increased risk of lung cancer for exposed firefighters versus those not exposed. The authors noted that all nine WTC firefighters with lung cancer were smokers.

The authors say: An association between WTC exposure and cancer is biologically plausible, because some contaminants in the WTC dust, such as polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and dioxins, are known carcinogens. Although some contaminants could cause cancer directly, WTC exposure could also trigger chronic inflammation, through microbial infections, autoimmune diseases, or other inflammatory disorders, all of which have been reported as factors in oncogenesis, both experimentally and epidemiologically.

They add: We believe the observed relative excess in cancer cases in WTC-exposed firefighters was unlikely to be the result of non-WTC firefighting exposures, because since 9/11, structural fires have decreased, personal protective equipment has improved, self-contained breathing equipment use has increased, and smoking rates in firefighters have declined.

They conclude: Our findings support continued monitoring of firefighters and other WTC-exposed cohorts to fully assess cancer risk related to these unique exposures.

In a linked Comment, Dr James M. Melius, New York State Laborers' Health Fund, New York, USA, says: This report and future cancer studies should provide reassurance that medical follow-up is being done in a way that will detect new disease patterns in a timely manner and, hopefully, while there is time to intervene.

He concludes: The study also comes at an important time for the federally funded medical follow-up of these workers, which has just been guaranteed for the next 5 years. This medical programme does not currently cover cancer treatment. The findings from the accompanying study show an increased overall cancer risk in these WTC-exposed firefighters, and significantly raised cancer risk at a few specific sites (ie, melanoma, thyroid, prostate, and non-Hodgkin lymphoma) compared with the general population. These heightened risks, tempered by concerns about potential surveillance bias, support careful consideration of the addition of cancer to the medical disorders covered in the programme. Waiting to do so until definitive cancer studies have been completed (probably many years from now) would be unfair and would pose a hardship for workers who willingly risked their health by responding without hesitation to the WTC crisis. Meanwhile, the New York City Fire Department and other groups caring for this population need to continue their efforts to assess cancer and other long-term health effects of WTC exposure.

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