Wednesday, August 24, 2016

FDA Study: Cancer Risks Nearly Nil for 1-2 Cigars Per Day

The FDA, which now regulates cigars, has taken the position that “cigar smoking carries many of the same health risks as cigarette smoking.”  The agency is requiring cigar packages and ads to display six new warnings, including:
  • Cigar smoking can cause cancers of the mouth and throat, even if you do not inhale.
  • Cigar smoking can cause lung cancer and heart disease.
  • Cigars are not a safe alternative to cigarettes.
However, an FDA staff report shows that smoking up to two cigars a day is associated with minimal significant health risks.

Last year, FDA staff, led by Cindy Chang, published in BMC Public Health (available here) a systematic review of the risks of cigar smoking, declaring that their action was “not a formal dissemination of information by the FDA and does not represent agency position or policy.” 

The authors reviewed 22 prospective epidemiologic studies on cigars and health outcomes; they produced tables of results for many smoking-related diseases. 

This entry will explore results for deaths from all causes and from cancers among men who are primary cigar smokers (no history of cigarette or pipe smoking).  Because the 22 studies employed different methods, and because they controlled or adjusted for various factors, the FDA authors did not provide overall summary risk estimates.

First, let’s look at mortality for all causes of death among cigar smokers, compared with never smokers.  (A relative risk, or RR, of 1 is no risk, and an RR confidence interval that includes 1 is not statistically significant.)

Table 1. Relative Risk Estimates For All-Cause Mortality Among Men Who Smoke Cigars

Publication, YearRelative Risk (95% Confidence Interval, CI)
Best, 19661.06 (0.92 – 1.22)
Kahn, 19661.10 (1.05 – 1.16)
Cole, 19741.15 (0.70 – 1.90)
Carstensen, 19871.39 (1.16 – 1.65)
Lange, 19921.60 (1.30 – 2.00)
Ben-Schlomo, 19940.48 (0.25 – 0.93)
Shanks, 19981.08 (1.05 – 1.12)

Table 1 shows that cigar smokers have an elevated risk for death from all causes.  With the exception of the Ben-Schlomo study, all of the estimates are elevated, and four are statistically significant.  So it appears that there is a modest increase in risk among cigar smokers for all causes of death.     

Next, let’s look at the risks for individual cancers. 

Table 2. Relative Risks For Cancer Mortality Among Men Who Smoke Cigars
Cancer SiteRelative Risk RangeNo. of Studies / No. of Significant Elevated Estimates

Mouth/throat4.0 – 7.93 / 3
Esophagus1.8 – 6.54 / 2
Stomach1.2 – 2.32 / 1
Liver3.1 – 7.22 / 2
Pancreas1.0 – 1.64 / 1
Larynx10.0 – 10.33 / 3
Lung1.6 – 7.66 / 5
Bladder0.9 – 1.94 / 0

It appears that, like cigarette smokers, cigar smokers have elevated cancer risks especially at places in contact with smoke, such as the mouth/throat, esophagus, larynx and lung.  For other sites, like the stomach, pancreas and bladder, elevated risks are minimal and/or based on very limited data.

In other research published by the FDA (here), primary cigar smokers consumed on average about 1 ½ cigars per day when they smoked.  This is relevant to a key epidemiology principle: the level of risk is related to the level of exposure.  Several studies in the Chang review reported results for smoking one or two cigars per day.  Here are those results: 

Table 3. Relative Risks (95% CI) for Mortality Among Men Smoking 1 or 2 Cigars Per Day

Shanks, 1998Shapiro, 2000Other Studies

All Causes1.02 (0.97 – 1.07)
1.04 (0.98 – 1.11)1


Mouth/throat2.12 (0.43 – 6.18)0 (0.00 – 0.00)
Esophagus2.28 (0.74 – 5.33)1.80 (0.60 – 5.00)

1.68 (0.95 – 2.97)2
Pancreas1.18 (0.69 – 1.89)0.60 (0.30 – 1.40)
Larynx6.45 (0.72 – 23.3)6.00 (0.70 – 53.5)
Lung0.90 (0.54 – 1.66)1.30 (0.70 – 2.40)1.14 (0.59 – 2.00)1
Bladder0.78 (0.29 – 1.71)0 (0.00 – 0.00)
1Kahn 1966, 5 cigars per day or fewer.
2Chao 2002, 5 cigars per day or fewer.

While some risk estimates are elevated, none are statistically significant.  The highest risks are for larynx cancer, but they are based on only two deaths in Shanks and one death in Shapiro.

What are the important take-home messages for cigar smokers with respect to risks for all causes of death and for smoking-related cancers?  FDA staff concluded that “cigar smoking carries many of the same health risks as cigarette smoking. Mortality risks from cigar smoking vary by level of exposure as measured by cigars per day and inhalation level [not discussed here] and can be as high as or exceed those of cigarette smoking.”

However, the data indicates that consumption of up to two cigars per day, while not completely safe, is neither associated with significantly increased risks for death from all causes, nor smoking-related cancers.        
In a subsequent post, I will present results for other diseases, including lung and cardiovascular disorders. 


Professor Twain said...

Thanks so much for this post. I am an occasional cigar smoker and a health researcher, although I have never published about tobacco control issues. I have seen the original papers that are cited in this review and understood the essence of the findings. Your blog post is very clear and straightforward and the referral to the manuscript is a great service. I have posted this link to a major online cigar board that is ready by many cigar lovers throughout the world.

The published research article shows a form of scientific cowardice that is troubling. The associations between moderate cigar smoking (which characterizes most cigar smokers) and health outcomes is nearly zero. Yet the authors fail to mention this very important finding. They hide behind the true but misleading statements that there is a main effect for cigar smoking on health, and a dose response relationship. Surely they couldn't have failed to note these findings, which have major health policy implications.

The timing on this is particularly key as FDA regulation of cigars is ramping up. For many cigar smoking is a relatively harmless activity, but it is being attacked like a major health risk. What's next, alcohol or sugar?

Roberto Sussman Livovsky said...

About 25 years ago I stopped smoking cigarettes and switched to moderate cigar and pipe smoking without inhaling. The health benefits were immense (much improved aerobic condition, no more month long bronchitis 3 times a year, etc). I appreciate very much reading your summary of epidemiological literature on cigar smoking, as well as your mention of the unfortunate and deliberate attempt of busybody regulators to spread fear mongering lies that contradict the epidemiological studies. While moderate cigar/pipe smoking without inhalation is not risk free (nothing is), it is a lot less risky than cigarette smoking (even the “low tar” cigarettes). My decision to replace cigarettes with cigars/pipes was my humble (and perhaps instinctive) effort for achieve a personal "Tobacco Harm Reduction". However, in all online and blog discussions on THR only smokeless tobacco and e-cigs are considered as safer alternatives to cigarettes. Cigar/pipe smoking without inhalation is never mentioned as a THR option. While smokeless tobacco and e-cigs may be safer than cigars/pipes, smoking the latter is still a valid THR option that should be (at least) mentioned.