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Clearing the Air

Aug 1, 2009 12:00 PM

By Sara Pyle

Researchers are divided on the hot-button issue of cancer presumption.

In April, the National League of Cities issued a report that trumpeted the failure of a TriData study “to establish (a) link between cancer and firefighting.” The NLC-commissioned study — which was based on a review of 17 of the 71 scientific articles TriData had found on the topic of firefighting and cancer, as well as interviews with NLC members in 48 states — concluded that there was not enough evidence to support cancer-presumption laws.

The report quickly came under attack by both the International Association of Fire Chiefs and the International Association of Fire Fighters, which identified several flaws in the scientific methodology and called the NLC's attempts to halt cancer-presumption laws “tobacco industry-style tactics.”

As the joint statement pointed out, NLC's report claims a lack of conclusive scientific evidence about the link between firefighting and cancer and urges that new legislation not be enacted until more research is done. Denying the scientific evidence and delaying legislation are both tactics uncovered in the internal documents of the tobacco industry as ways to avoid tobacco-limiting laws.

“If the National League of Cities is truly concerned about evaluating this issue ‘objectively and scientifically,’ as they stated in their press release, then they need to look at all the data in a scientifically sound manner,” IAFC President Larry Grorud said in a statement. “Data-based research is one of our strongest allies in reducing firefighter deaths, injuries and disease, but not if we frame the questions or manipulate the data with an end result already in mind.

“Rather than ignoring it, we ought to be looking closely at the ample data that does indicate a link between firefighting and cancer and how that data may support prevention,” the statement continued. “Future investments in research need to be forward-focused on preventing firefighter illness and deaths. This report offers the men and women of the fire service no path forward.”

The NLC long has opposed cancer-presumption legislation. With the current national budget crisis, cities are looking for ways to save money and cut budgets. NLC Executive Director Donald J. Borut urged that “states should not pass laws requiring cities to take on difficult financial burdens with no clear scientific connection between illness and occupation.” Twenty four states and seven Canadian provinces currently have cancer-presumption laws, which have been enacted based on the research available about cancer among firefighters.

The primary question is whether there is a clear scientific connection between cancer and the duties of firefighting. While the debate continues to rage in the political world, the answer, according to well-done and rigorous scientific studies, seems clearly to be “yes” for several categories of cancer.

Medical and scientific experts have found the NLC-commissioned study to be both flawed and arbitrary in its evaluation. Dr. Sami Youakim, who published an article on the topic in the peer-reviewed medical journal The Archives of Environmental and Occupational Health, said he believes the findings “should be used for nothing at all,” much less to set policy.

Dr. Tee Guidotti, an expert on firefighter health, cancer and cancer presumption — and who has published several articles on the topic — said the report “brings nothing new to the discussion of cancer among firefighters and is well behind current discussion in professional circles.”

“The way that the paper was produced did not give me confidence,” he said. “I was interviewed by the two research assistants when they began. They interviewed me at the beginning of their work for about an hour. I briefed them on the intricacies of the epidemiology and causation analysis. They did not speak to me again. I obviously failed in briefing them because none of the essential points I made to them are reflected in their report.”

Study Conflicts

One challenge when looking at the relationship between firefighting and cancer is that the prevalence of cancer, even in high-risk populations, is low compared to the whole population, which makes it necessary to study large groups of people to be able to detect the rates and compare differences. Studies with larger samples are more accurate than smaller studies and should be given more weight when looking at the overall relationship.

Researchers are divided on the hot-button issue of cancer presumption.

“The report suggests that the level of knowledge regarding the risk of cancer among firefighters is scanty,” Guidotti said. “Actually, the data available on firefighters is rich and among the most complete that we have for any occupation. The problem is that all of these cancers are rare [in the epidemiological sense] and so any one study has low statistical power. In such situations, there will always be some studies that are negative and some that are positive. But epidemiology is not a game played with a scorecard. One needs to examine the individual studies carefully and to look for overall patterns to make sense of it all.”

Grace LeMasters, of the University of Cincinnati College of Medicine, published a quantitative synthesis of firefighting and cancer studies. Instead of just conducting a selective review of a few studies without the benefit of clear criteria for inclusion, she and her team mathematically combined the results of the 32 studies that met strict entry requirements. The technique, referred to as a meta-analysis, is now the gold standard for answering research questions like whether cancer and firefighting are related.

Her results were alarming — 12 types of cancer were either probably or possibly related to firefighting. LeMasters identified as probable: multiple myeloma, non-Hodgkin's lymphoma, and prostate, testicular, skin, malignant melanoma, brain, rectum, buccal cavity/pharynx, stomach and colon cancers; and as possible, leukemia. For example, firefighters were 53% more likely to develop multiple myeloma and twice as likely to develop testicular cancer.

LeMasters pointed out that most comparisons were made between firefighters and the general population in the studies she included. She suggested that the “actual risk of cancer may be under-estimated due to the “healthy worker effect,” which is related to the strict physical entry requirements, maintenance of better physical fitness, and good health benefits that affect firefighters but are less likely to impact the general population, where some individuals may be employed but others are not, or where some individuals may have health insurance but others do not.

Youakim completed a meta-analysis that not only examined several studies in aggregate, but also divided the samples into the number of years worked in the fire service. His research found that some cancers, while not significantly related to firefighting when studied as a group, did indicate an increased risk for mortality as years of service increased. For example, firefighters with 30 or more years of service were more than six times as likely to die from kidney cancer, nearly three times as likely to die from leukemia, 50% more likely to die from colon cancer and two-and-a-half times more likely to die from brain cancer than comparison populations. For firefighters with 40 or more years of service, the data was even more distressing. Risk of death from kidney cancer was more than 36 times that of the comparison populations, almost five times for kidney cancer and nearly six times for bladder cancer.

He points out another challenge with this type of research question is that studies “may have a tendency to dilute findings based on exposure.” Most studies treat all firefighters in the same manner without taking into account the amount of exposure they have to firefighting activities, which could underestimate risk for some and overestimate it for others. As the IAFC response noted, Youakim's article was completely ignored by the NLC report.

Guidotti published an article in the peer-reviewed journal Occupational Medicine where he evaluated both the scientific evidence for the relationship between cancer and firefighting as well as the medico-legal standards for presumption laws. The article stated that, “the epidemiological literature on firefighters is among the most complete and detailed for any occupation. The general quality of epidemiological studies on firefighters since 1980 is high and the methods employed are generally similar for the prospective cohort studies, although no two studies are or can ever be identical.”

According to Guidotti, workers compensation and statutory presumption issues are evaluated based on the weight of the evidence instead of scientific certainty. He said, “This report makes the common mistake of using the standard of scientific certainty where the standard of the balance of probabilities applies. In civil law, workers' compensation and legislated presumption, the inherent requirement is that the evidence supports that a causal association is more likely than not, not that we are 95% or more certain. The [NLC] report is using the wrong criteria. No issue in law or legislation is decided on scientific certainty because it is too high a standard for dispute resolution.”

Guidotti's work outlines the frameworks within which different types of cancers can be classified. He concluded that presumption is justified for bladder, kidney, testicular and brain cancers, lung cancer among non-smokers, non-Hodgkin's lymphoma, leukemia and myeloma.

Guidotti did praise the NLC report for its in-depth explanation of the issues related to cancer presumption. “It is an excellent compendium of the laws and financial issues and points out many of the operational problems and implementation issues with state legislation, which is inconsistent because they have been passed over the years and many predate the current wave of interest. That is the true value of the report.”

Additional research

As with any area of research, additional scientific inquiry into this topic will continue to shed light on the relationship between cancer and firefighting in more detail. For example, it will be important to understand what exposures are most closely linked to the different types of cancers, to determine which groups are most at risk and to determine whether there are safety measures that can be implemented to decrease cancer rates.

As highlighted in the NLC report, firefighting involves interaction with a numerous known carcinogens. While science continues to uncover all the dangers and understand exactly what the risks are, those in the fire service are encouraging firefighters to continue their vigilance when it comes to health and safety. Consistent use of PPE during firefighting and overhaul, maintaining healthy behaviors related to fitness and nutrition and limiting exposure to diesel exhaust and other carcinogens are key to maintaining firefighter health.

“Fire chiefs, officers and firefighters must continue to work toward the goals of presumption laws to protect firefighters — as well as strict leadership to minimize exposure by firefighters by full use of PPE,” said Chief Billy Goldfeder, chair of the IAFC's Safety, Health and Survival Section. “Who knows, after seeing those ridiculous headlines, how many firefighters accepted it to be fact and took less precautions in our already risky jobs?”