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Coffee’s Relationship to Human
Cancer: Did IARC’S 2016 Evaluation
Get It Right?
James R. Coughlin, Ph.D. CFS
President, Coughlin & Associates:
Food/Nutritional/Chemical Toxicology & Safety
Aliso Viejo, California USA
www.linkedin.com/in/jamescoughlin
26th International Conference
on Coffee ScienceKunming, China
November 14, 2016
IARC (Lyon) Evaluated Coffee in May 2016, but…
Did They Get It Right?
I Don’t Believe They Did!!!
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Presentation Outline
What is IARC?
– History and Working Procedures
– Recent activities, 2015-2016
IARC and Coffee:
– First Evaluation 1990-1991; Second Evaluation 2016
Key IARC Coffee Findings in May 2016
Did IARC Get it Right?
Controversies over Recent IARC Classifications
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What is IARC?
International Agency for Research on Cancer founded in 1965,
headquartered in Lyon, France, operates under auspices of the World
Health Organization, and goal to promote international collaboration in
cancer research.
Since 1972, the “IARC Monographs on the Evaluation of Carcinogenic
Risks to Humans” Programme has evaluated the weight of the evidence
that an agent, a chemical compound, a complex mixture (including an
individual food), an occupational exposure, a physical or biological
agent or a lifestyle factor, can influence the risk of cancer in humans.
IARC convenes groups of scientists from around the globe in Lyon three
times a year, classifies the evaluated substances into 4 Categories [see
upcoming slide], and publishes the IARC Monographs Series.
IARC evaluates only HAZARD, not RISK, in spite of “Risk”
in the title.4
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How does IARC classify agents/substances with
respect to their cancer risk?
IARC classifies compounds into 4 Groups based on the available
scientific evidence for increasing cancer risk in animals and humans.
The four classifications correspond to decreasing available evidence
for cancer risk.
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Group 1 Carcinogenic to humans
Group 2A Probably carcinogenic to humans
Group 2B Possibly carcinogenic to humans
Group 3 Not classifiable as to its carcinogenicity to humans
Group 4 Probably not carcinogenic to humans
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IARC vs. “Agriculture and Foods” (2015-2016) -
Monograph Meetings
March 2015 – Glyphosate (“Roundup” herbicide for GMOs)
Group 2A, “Probable Human Carcinogen”
“Sufficient evidence” in animals, “Limited” epi evidence (non-Hodgkin
lymphoma) + Mechanisms (genotoxicity & oxidative stress)
Monsanto filed lawsuit to prevent California Prop 65 listing in Jan 2016
June 2015 – 2,4-Dichlorophenoxyacetic acid (2,4-D) (pesticide):
Group 2B, “Possibly Carcinogenic”
First agency in the world to call the animal studies even “Limited
evidence”; but oxidative stress mechanism raised the call above the
Group 3 “not classifiable” category
October 2015 – Red and Processed Meat: [see following slide]
Coffee – Monograph meeting May 24-31, 201611
IARC: Red & Processed Meat Decisions (Oct 2015)
22 invited scientists on Working Group; 8 global meat industry
Observers (were silenced!); 8 days of deliberations; conclusions
published two week later in Lancet Oncology
RED MEAT: [No Sufficient Evidence = No Calif. Prop 65 listing]
Group 2A, “Probable Human Carcinogen”
Limited Evidence in humans, colorectal cancer only
Inadequate Evidence in animals
Mechanistic considerations raised the classification
PROCESSED MEAT: [Will eventually be listed by Calif. Prop 65]
Group 1, “Human Carcinogen”
Sufficient Evidence in humans, colorectal cancer only [Relative Risk
=1.18; barely statistically significant, translates to 18% increase in
risk]
Inadequate Evidence in animals
Mechanistic considerations raised the classification.
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“Nitrite in Combination with Amines or Amides” –
Proposition 65 Carcinogen Listing Challenge
IARC Monograph No. 94 (2010) on “Ingested Nitrite and Nitrate”
classified as Group 2A “probably carcinogenic”
American Meat Institute and U.S.-based Grocery Manufacturers
Association submitted comments objecting to this “Authoritative
Bodies” listing in May 2014
After consideration of our comments, the state determined that the
regulatory criteria for automatic listing had not been met
But the state notified us in May 2015 that they will ask the Carcinogen
Identification Committee (CIC) to consider this for listing
The CIC will decide this tomorrow; update – the CIC voted unanimously
not to list, agreeing with our industry comments.
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IARC: Positive Vs. Negative Health Studies
IARC gives greater weight to positive (adverse) results than to
negative results, even when the latter are from higher-caliber
studies.
IARC only needs evidence for one human organ site (e.g.,
meat/colorectal) or one animal cancer bioassay (e.g., 4-MEI in
coffee) to classify an agent or substance as carcinogenic.
This explains why, of the nearly 1,000 substances & agents IARC
has evaluated, only one has been categorized as Group 4,
“probably not carcinogenic to humans.”
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IARC & COFFEE
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Key Concerns Going Into Coffee Meeting
Bladder cancer – will IARC finally recognize that they got it wrong
in 1991? There are many newer & better epi studies and a greater
recognition of smoking as the confounder that was not accounted
for.
Childhood leukemia and childhood brain cancer – Dr. Elizabeth
Milne, Australian on the WG, has published several human studies
of mothers’ coffee consumption
Talc in baby powder [Group 2B in Monograph No. 93, 2010] as
the model for concern, 2016 lawsuits in U.S.
Will Mechanisms be “tortured” to raise the classification?
Animal carcinogens & mutagens
Oxidative stress in animals and humans
Cytotoxic compounds
Genetic polymorphisms
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Where Should IARC Have Come Out?
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Coffee and Cancer Risk
This all started with bladder cancer concerns in the late 1970’s,
pancreas cancer in 1981, and all other organs followed. Animal
cancer studies showed no increases in tumors and some protective
effects were observed.
Coffee was shown to contain dozens of animal carcinogens, many
produced by the “Maillard Browning Reaction” in the presence of
heat, including IARC carcinogens acrylamide, furan, benzo[a]pyrene
& 4-Methylimidazole
Nearly 600 human epidemiology studies have been published since
the 1970’s on most human organs
Fortunately, after 4 decades of human and animal research, most
health authorities across the globe now agree that coffee drinking is
NOT a cancer risk, but actually reduces the risk of several human
cancers!
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“FOR MOST CANCER SITES, THERE IS A SIGNIFICANT AMOUNT OF
EVIDENCE SHOWING NO DETRIMENTAL EFFECT OF CONSUMPTION
OF UP TO 6 CUPS OF COFFEE/DAY IN RELATION TO CANCER
OCCURRENCE. IN FACT, SOME OF THE EVIDENCE…SUGGESTS
THAT COFFEE MIGHT PREVENT SOME CANCERS.”
[REVIEW BASED ON OVER 500 PUBLICATIONS]
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“Epidemiologic Evidence on Coffee and Cancer”
Lenore Arab (U. of California, Los Angeles)
Liver and endometrial cancers - a strong and consistent protective
association
Colorectal cancer - the association is borderline protective
Breast, pancreatic, kidney, ovarian, prostate, gastric cancer - no
association
Bladder cancer - very weak increase in risk for heavy coffee consumption
in some studies, but this may be an indication of confounding by smoking
Childhood leukemia - ambiguous risk with mother’s consumption of
coffee at high levels of daily consumption, needs further study.
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Using a Benefit-Risk Approach for
Coffee…
The “Holistic” Approach
~
“Coffee - Cancer Paradox”
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“Benefit-Risk” Evaluation of Coffee Consumption
~ What IARC Does NOT Do ~
Coffee has > 2,000 chemical components, mostly flavor/aroma
compounds, produced by roasting in the “Maillard Browning
Reaction,” but also trace levels of dozens of animal carcinogens
[acrylamide, furan, 4-MEI, caffeic acid, PAHs, aldehydes &
dicarbonyls, Ochratoxin A, metals, etc.]
Coffee also contains many health-protective chemicals, including
polyphenolic antioxidants, both naturally occurring (the chlorogenic
acids) and heat-produced (the brown polymeric melanoidins)
Public health & regulatory authorities should weigh the health
effects of all coffee components when deciding about safe
consumption levels
Dr. Ernesto Illy first called coffee’s “benefit-risk” evaluation the
“Holistic Approach” - looking at coffee as a whole food!
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The “Coffee / Cancer Paradox”
But global health and regulatory authorities now agree that coffee
drinking is NOT causing any increased risk of human cancer
In fact, human studies show significant risk reductions for numerous
cancers in spite of the presence of many animal carcinogens
How can this be?
Naturally occurring antioxidants (the chlorogenic acids)
Heat-formed antioxidants (the brown melanoidin polymers)
Chemicals that induce detoxification enzymes
I have termed this the “Coffee-Cancer Paradox” – and it results from
doing the “Benefit-Risk” evaluation using the “Holistic Approach”
So, the Paradox is – Coffee contains many animal
carcinogens at trace levels but actually reduces some
tumor risks without raising others.
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IARC Controversies are Raging in the Media,
in Industry and within and amongst Public
Health & Regulatory Bodies!
~ ~ ~
Mainly from Agriculture and Foods
Classifications
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Personal Thoughts ~ IARC Got COFFEE Wrong! ~
IARC needs only one human organ to conclude carcinogenic effects
and to arrive at a Group 2B “possibly carcinogenic” or worse. They
have done this hundreds of times…using just one human organ or
one animal cancer bioassay (e.g., U.S. National Toxicology Program).
But for coffee, they did not have even one human organ to pin
positive cancer evidence on, but then declared “We just can’t
classify or decide.”
Even worse, the IARC webpage, “Debunking the Myths…”
“Does the IARC classification mean that coffee is safe in terms
of a potential link to cancer?
No. An evaluation of not classifiable as to its carcinogenicity to
humans (Group 3) does not mean that a substance has been
proven to be safe.”
For IARC to conclude “NO” on “Is coffee safe?” is a complete
misrepresentation of decades of scientific studies; and calling coffee
Group 3 “not classifiable” represents poor scientific judgment.
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Personal Thoughts ~ IARC Got COFFEE Wrong! ~
However, I and the global coffee industry will be happy to take this
“partial victory”…since coffee was in fact downgraded from Group 2B
“possibly carcinogenic to humans” to Group 3, correctly eliminating
the bladder cancer controversy from 1991
But IARC has been on the rampage against agriculture & foods for
the last year and a half, and there are more evaluations to
come [aspartame, sucralose, dietary iron, beta-carotene]
And most of what IARC does is loaded with Biases & Conflicts of
Interest on their Working Groups, while they accuse industry-
sponsored scientific researchers and industry scientists as being the
only ones with biases and conflicts
And a supposedly systematic peer review of each substance is
actually designed to “torture” the hazard/risk side of the equation
while always ignoring the benefits side.
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~ Summary & Conclusions ~
IARC was not able to associate even one human organ to an increased risk of
cancer due to coffee consumption.
Their correct evaluation on breast, prostate and pancreas cancer should have been
sufficient to give coffee a Group 4, “probably not carcinogenic to humans.”
For liver and uterine endometrium cancers, where they correctly concluded
“reduced risk” of cancer, IARC would need to establish a new category of Group 5,
“probably reduces the carcinogenicity to humans.”
With three organs showing no carcinogenic effects and two organs showing
reduced risk of cancer, why did they not conclude something more favorable than
Group 3 “not classifiable”, especially when only one organ is used to justify Group
2B or worse?
In sum, while their overall cancer conclusions were scientifically valid and correct,
their final classification as Group 3 is totally unsupported by the vast scientific
evidence on coffee and cancer.
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Thank You!
Questions?
