Together, the six otolaryngologists in this study helped to defend the tobacco industry in more than 50 cases.

“By highlighting an exhaustive list of potential risk factors, such as alcohol, diesel fumes, machinery fluid, salted fish, reflux of stomach acid, mouthwash and even urban living, they created doubt in the minds of the jurors as to the role of smoking in the plaintiff’s cancer,” the study said. “Evidence shows that this testimony, which was remarkably similar across cases, was part of a defense strategy shaped by tobacco’s law firms.”

The study said the physicians were “well-coached” by tobacco lawyers, and their testimony was “faithful to the tactical narrative that there are many, many causes of head and neck cancer — and that factors other than smoking must have caused the plaintiff’s disease.”

‘Obvious fallacy’

The study said: “An obvious fallacy of this argument lies in the fact that literally billions of nonsmoking people are exposed regularly to gasoline fumes, use cleaning solvents, eat salted fish or live in urban environments. Were these causative factors for head and neck cancer, with even a minute fraction of the potency of tobacco, the rate of head and neck cancer among nonsmokers would be much greater than what has been observed.”

Evidence shows that this testimony, which was remarkably similar across cases, was part of a defense strategy shaped by tobacco’s law firms.

Jackler has for years conducted scholarly research focusing on the tobacco industry’s influence on public health. He has published multiple studies on the impact of the tobacco industry’s advertising, marketing and promotion.

In this study, he reviewed nine cases that resulted from a 1999 Florida class-action suit (Engle v. Liggett) in which an award of $145 billion was reversed on appeal. The Florida Supreme Court decision in 2006 that upheld the Engle jury decision of widespread wrongdoing on the part of the tobacco industry enabled individual cases to proceed.

“The addictiveness of nicotine, the dangers of tobacco and the track record of industry deception and misconduct are considered factual in subsequent trials,” the study said. "The legacy of the Engle decision has been a series of some 8,000 individual ‘Engle progeny’ cases. As these cases have primarily focused upon whether on not tobacco caused the plaintiff’s disease, testimony by medical experts has been central to their adjudication.”

Plaintiffs’ cancers

For the study, Jackler examined a small fraction of these progeny cases. Patients in these cases had cancer in sites such as the larynx, the mouth and the esophagus. All of the plaintiffs in these cases were long-term, heavy smokers — more than a pack a day for many years. The key issue in these lawsuits was whether it was more likely than not that smoking caused the individual plaintiff’s cancer (greater than 50 percent probable is the legal standard). Although since the 1990s tobacco companies have admitted that their products cause cancer, in litigation they vigorously argue that smoking did not cause an individual plaintiff’s cancer.

“Otolaryngologists in this study routinely expressed the opinion that, more likely than not, tobacco did not cause the smoker’s head and neck cancer,” the study said. It added: “Among habitual smokers it is not credible to opine that rare and hypothetical causes, taken singly or as a lengthy list, are more likely than causative than tobacco to a degree remotely approaching [greater than 50 percent].”

In contrast, the scientific literature demonstrates that tobacco directly contributes to head and neck cancers at a greater than 50 percent likelihood, Jackler said.

“[The tobacco industry identifies] the best experts that money can buy, [trains] them in their well-honed narrative to manufacture doubt in the minds of the jury and [makes] use of them over and over in case after case,” the study said. Given the ethical traditions of medicine, it seems likely that these physicians believe their well-compensated testimony on behalf of tobacco companies occurs in the shadows, out of view of their families, friends and professional colleagues, Jackler said.

Information about Stanford’s Department of Otolaryngology-Head and Neck Surgery, which supported the work, is available at http://med.stanford.edu/ohns.