The Hole Story: Ventilated Filters Make Smoking More Deadly  

Kristin Jenkins

May 22, 2017

The ventilation systems built into cigarette filters in the mid-1960s to reduce tar and make smoking 'smoother' and 'safer' were responsible for the paradoxical rise in rates of lung adenocarcinoma — even as rates of other lung cancer subtypes dropped along with the number of smokers. These conclusions were in the 2014 US Surgeon General's report on the health consequences of smoking.

Now, two new weight-of-evidence reviews have pinpointed 25 "causation analysis evidence blocks" that could support an outright ban of filter ventilation, according to lead author, Peter G. Shields, MD, deputy director of the Comprehensive Cancer Center, the Ohio State University Wexner Medical Center, in Columbus, and colleagues.

The review found that between the 1960s and the 1980s, the health risks associated with smoking jumped almost 2-fold in men and increased 10-fold in female smokers. At the same time, the relative risks for adenocarcinomas rocketed from 4.6 to 19.0 in men and from 1.5 to 8.1 in women — even though the risks for other lung cancer subtypes didn't increase. "Thus, there was a paradoxical increase for lung adenocarcinomas while squamous cell cancers decreased with decreased smoking rates," the review authors write.

"The analysis strongly suggests that filter ventilation has contributed to the rise in lung adenocarcinomas among smokers," they say in a report published online May 22 in the Journal of the National Cancer Institute.

"Based on these weight-of-evidence reviews, the FDA [Food and Drug Administration] should embark on a regulatory process of data evaluation and consider regulation(s) for the use of ventilation in filters, up to and including a ban on their use," the authors conclude.

"The prime point is to rally the troops to get the FDA to focus on this," Dr Shields told Medscape Medical News. "To me, this is a policy paper. Physicians can't be silent."

This is a policy paper. Physicians can't be silent. Peter D. Shields

Ventilation holes in filters are now found in nearly every brand of cigarettes, and they make smoking even more deadly, Dr Shields elaborated in an interview.  

The tiny filter holes slow down tobacco combustion, giving smokers more puffs per cigarette but also allowing more toxic constituents to form, increasing the mutagenicity of the smoke, the review authors explain. To get the requisite nicotine hit from a cigarette with a ventilated filter, a smoker must also inhale more deeply, drawing smoke farther into the lungs and exposing cells vulnerable to adenocarcinoma.

Increasing amounts of tobacco-specific nitrosamines can also be found in new blended tobaccos that provide a "smoother" smoking experience, albeit with more carcinogens, Dr Shields commented. This makes smoking more dangerous than ever before, and patients need to know this, he emphasized.

"As part of your risk counseling, tell patients who smoke that the cigarettes today are more deadly than the cigarettes from 30 or 40 years ago. We need to take away smokers' perception that any cigarette is safe. It's like putting your head in a chimney," Dr Shields said.

Increased Risk for Adenocarcinoma

In an accompanying editorial, Jonathan M. Samet, MD, and Lilit Aladadyan, MS, MPH, say that ending filter ventilation "could be a 'no regrets' action that would benefit public health."

Dr Samet is professor and Flora L. Thornton Chair for the Department of Preventive Medicine at the Keck School of Medicine at the University of Southern California (USC) in Los Angeles, and Aladadyan is center director for the USC Tobacco Center of Regulatory Science.

The editorialists note the review looked at a "large and somewhat poorly circumscribed body of literature" and that the evidentiary threshold required for the FDA to take action is not supported by any record of precedents.

However, they also say that the review's conclusion about the contribution of filter ventilation to rising rates of lung adenocarcinoma in smokers "is well justified" and supports "the indictment of filter ventilation as increasing risk for adenocarcinoma."

Filter ventilation was originally designed to lower smoking machine tar yields in so-called light cigarettes marketed primarily to women as a "healthier" alternative to regular cigarettes. "This was done to fool smokers and the public health community into thinking that they actually were safer," Dr Shields said in a statement.

In 2009, the Family Smoking Prevention and Tobacco Control Act gave the FDA authority to ban tobacco companies from labeling and marketing cigarettes as "low tar" or "light."

Dr Shields has served as an expert in class action suits against tobacco companies marketing light cigarettes as a healthier alternative. He's also heard lawyers for Big Tobacco say peer-reviewed evidence was needed. "From our perspective, there is more than enough data to start the process and it's time for regulation," he said. "We believe that such an action would drive down the use and toxicity of conventional cigarettes and drive smokers to either quit or use less harmful products. There are some open questions about unintended consequences for enacting a ban, which provides for an important research agenda."

Future clinical trials could assess smokers switching to filtered cigarettes without ventilation, using a panel of biomarkers to measure exposure to carcinogens and lung toxicants, markers of oxidative damage and inflammation in lung, blood, or/and urine, the review authors suggest. At present, human exposure biomarker studies do not appear to support a causal relationship, they didn't measure exposure in the lung or "utilize known biomarkers of harm," they note.

Smokers' perceptions, and transition to alternate products, should also be assessed, looking at differences by race and ethnicity, sex, age, and vulnerable populations. The effect of filter ventilation on the risk for other diseases, such as chronic obstructive pulmonary disease, could also be studied, they say.

This study was supported by the National Cancer Institute of the National Institutes of Health and the FDA Center for Tobacco Products. Dr Shields and coauthors Neal L. Benowitz, MD, and Theodore M. Brasky, PhD, disclose they have served as consultants and expert witnesses in litigation against tobacco companies. Coauthor K. Michael Cummings, PhD, MPH, declares a relationship with Pfizer Inc. The study authors and editorialists have disclosed no relevant financial relationships.

J Natl Cancer Inst. Review published online May 22, 2017; editorial published online May 19, 2017. Abstract, Editorial

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