Presentation to The Cross Party Oireachtas Group on Alcohol Harm in December 2014 by Dr Marie Laffoy.

1. Alcohol and Cancer
Focus on Breast Cancer
Presentation to
The Cross Party Oireachtas Group on Alcohol Harm
4th December 2014
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2. 1. Risk factors for cancer
The main life style risk factors for cancer are smoking, overweight / obesity, physical
inactivity, alcohol and UV radiation.
Alcohol is a Group 1 carcinogen. By this, we mean that the International Agency for
Research on Cancer (IARC) has proven that there is a causal link between
alcohol and cancer of the mouth, pharynx, larynx, oesophagus, liver, large
bowel and female breast. There is no safe lower limit, at which alcohol has
no effect on cancer risk. However, a person’s risk of getting cancer depends
on the amount they drink. All types of alcohol have the same effect. There is
a long lag time from consumption to getting cancer 1,2.
2. Low-Risk Drinking Guidelines
The Department of Health has issued ‘low-risk’ drinking guidelines3:
· 11 standard drinks a week for a woman
· 17 standard drinks for a man.
A standard drink is ½ pint beer, a single measure of spirits or a small glass of wine.
3. How does alcohol cause cancer?
The main mechanism of action is that alcohol is broken down in the body to
acetaldehyde, which is proven to cause cancer. Alcohol also increases circulating
oestrogen levels, which is linked to breast cancer.
The cancer risk from alcohol consumption combined with tobacco smoking is
multiplicative and is vastly greater than either smoking or drinking alone. This
combination greatly increases the risk of mouth, pharynx, larynx and oesophageal
cancers. Up to 90% of larynx cancers can be explained by smoking and drinking.
Overall 50% of head and neck cancers are due to alcohol 4.
4. Alcohol Consumption in Ireland
The volume of alcohol consumption in Ireland is higher than European average,
approximately 11 litres of pure alcohol per person per year.
The Health Research Board (2013) published research on people’s self-reported
alcohol consumption5. Key findings were:
· 75% of the alcohol consumed was done so as part of a binge drinking session
· Self-defined ‘light or moderate drinkers’ actually drink 60g or more of alcohol
on a typical drinking occasion (equivalent to binge drinking) and do not realise
that they consume alcohol in an unhealthy manner
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3. · As a nation, we greatly underestimate the amount we drink and we drink in a
harmful way.
5. Alcohol and Breast Cancer
Over 100 research studies have examined the association between alcohol
consumption and breast cancer. There is clear and consistent evidence of the
association. Risk increases with increasing alcohol intake. For every 10 grams of
alcohol consumed per day (one standard drink) there is a 7% increase in the risk of
breast cancer.
A meta-analysis of 53 studies (58,000 women with breast cancer) showed that
women who drink 45 g pure alcohol / day had a 1.5 times the risk of developing
breast cancer compared to non-drinkers6. Table 1 shows how risk increases as levels
of consumption increase.
Table 1 Relative risk of breast cancer by alcohol consumption levels
Amount consumed/day Relative Risk
Abstainer 1
0.25-19.9g (0-2 drinks) 1.15
20-39.9g (2-4 drinks) 1.32
40+g >4 drinks 1.46
The Million Women Study (28,000 women with breast cancer) found a slightly higher
estimate of breast cancer risk i.e. every 10 grams of alcohol / day was associated
with a 12% increase in the risk of breast cancer 7.
The Nurses Health Study, a prospective observational study of over 100,000 nurses
aged 34-59years, gathered data on alcohol consumption since 1980 and updated it
every four years. The nurses were followed up to 2008. Results showed that the risk
of ER+PR+ breast cancer increased at consumption more than 5g/day [½ a standard
drink/ day]8.
A prospective study of women aged 18-22 years, followed up for 10 years, in the
Nurses Health Study, found a strong positive dose response relationship between
developing proliferative benign breast disease and alcohol consumption. Compared
to non-drinkers, those who drank up to 5g per day had an 11% increased risk. Those
who drank 3-7 drinks / week increased their risk by 36%. Proliferative benign breast
disease has a two-fold increased risk of breast cancer 9.
6. How much can risk be reduced?
In a study of eight European countries, Schutze examined the fractions of cancer that
are attributable to alcohol consumption and determined how much of the cancer
risk is due to drinking over the recommended upper limit 10. This research involved
109,118 men and 254,870 women mostly between 35-70 years. For breast cancer,
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4. drinking over the recommended limit accounted for 80% of the excess risk. [The
recommended limit was set at 12g/d – equivalent 8.4 standard drinks / week].
7. What does this mean for Ireland?
Research conducted by the NCCP in 2013 found that alcohol is associated with
approximately 900 new cancer cases per year and 500 cancer deaths 11. The
research examined Cancer Registry incidence data and CSO mortality data
for 2001-2010. As expected, over 50% of head and neck cancers were
associated with alcohol consumption; 12% of breast cancers were
associated with alcohol consumption (approximately 300 new cases per
year). This is higher than the European study findings (which found that, on
average, 5% of breast cancers were associated with alcohol, range2-8%)10.
8. Conclusions
Alcohol causes cancer. The more we drink the higher our risk of cancer. The cancers
caused by alcohol can take many years to develop, so the effect of drinking
habits today will be seen well into the future.
Drinking over the Department of Health recommended limits accounts for much of
the increased risk of alcohol related cancers in Ireland. At least half of
alcohol related cancers could be avoided by drinking within recommended
levels.
While the highest risk is for head and neck cancer, the greatest impact in Ireland
relates to breast and bowel cancer, simply because these are common
cancers.
In relation to alcohol and breast cancer, a sensible life-long approach to
consumption is needed. The best advice is ‘less is best’.
There are many risk factors for breast cancer, see appendix. Importantly alcohol is an
avoidable risk factor. All women need to be aware of the modest but not
insignificant risk from alcohol. They can then consider the benefit of reducing their
alcohol intake, particularly in light of other risk factors they may have for breast
cancer.
Women with higher risk, including women with a personal history or a strong family
history of breast cancer might consider the benefit of reducing their alcohol
consumption even further below the DOH recommended levels.
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5. References
1. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans.
Alcohol consumption and ethyl carbamate . IARC Monographs on the
Evaluation of Carcinogenic Risks in Humans 2010;96:3-1383.
2. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans.
Personal habits and indoor combustions. Volume 100 E. A review of human
carcinogens. IARC Monographs on the Evaluation of Carcinogenic Risks in
Humans 2012;100(Pt E):373-472.
3. Steering group report on a National Substance Misuse Strategy. February
2012. Department of Health. Dublin. www.dohc.ie
4. Helmut K Seitz, Felix Stickel; Molecular mechanism of alcohol-mediated
carcinogenesis . Nature Reviews Cancer 599-612 August 2007
5. Long J, Mongan D (2014) Alcohol consumption in Ireland 2013: analysis of a
national alcohol diary survey. Dublin. Health Research
Board.www.drugsandalcohol.ie/22138
6. Hamajima N, Hirose K, Tajima K, et al. Alcohol, tobacco and breast cancer--
collaborative reanalysis of individual data from 53 epidemiological studies,
including 58,515 women with breast cancer and 95,067 women without the
disease. British Journal of Cancer 2002;87(11):1234-1245.
7. Allen NE, Beral V, Casabonne D, et al. Moderate alcohol intake and cancer
incidence in women. Journal of the National Cancer Institute
2009;101(5):296-305.
8. Lew J, Freedman N, Leitzmann M, Brinton L, Hoover R, Hollenbeck A,
Schatzkin A, Park Y. Alcohol and Risk of Breast Cancer by Histologic Type and
Hormone Receptor Status in Postmenopausal Women Am J Epidemiol. Aug 1,
2009; 170(3): 308–317. doi: 10.1093/aje/kwp120
9. Liu Y, Tamimi R, Berkry C, Intakes of Alcohol and Folate During Adolescence
and Risk of Proliferative Benign Breast Disease. Paediatics. (doi:
10.1542/peds.2011-2601
10. Schutze M. Alcohol attributable burden of incidence of cancer in eight
European countries based on results from prospective cohort study. BMJ
2011; 342:d1584
11. Laffoy M, Mc Carthy T, Mullen L, Byrne D, M Martin J. Incidence and
Mortality due to Alcohol in Ireland: An analysis of 10-year data, Ir med J;
2013; 106 (10) 294-297
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6. Appendix Risk factors for breast cancer
A risk factor is anything that affects a person’s chance of getting a disease. Cancers
have many different risk factors e.g. smoking is the main risk factor for lung cancer.
Risk factors for breast cancer are described as being either non-modifiable or
modifiable.
1. Non-modifiable risk factors are those that cannot be changed, for example:
· Gender: being a woman is the greatest risk factor for breast cancer
· Ageing increases risk; 70% of breast cancers are in women over the
age of 50
· Family history of breast cancer (including genetic mutations e.g.
BRCA1 and BRCA 2) accounts for of 5-10% of breast cancer
· Personal history: women with a personal history of breast cancer are
at increased risk of a subsequent breast cancer
· Some proliferative benign breast conditions can increase risk
· Girls who had radiation therapy to the chest for another cancer (e.g.
lymphoma) are at increased risk of breast cancer in later years.
2. Modifiable risk factors are those which can be changed. These include:
· Nulliparity: Women who have no children or who had their first child
after age 30 have a slightly higher breast cancer risk. But having many
pregnancies and becoming pregnant at a young age reduce breast cancer risk
· Breastfeeding lowers breast cancer risk, especially if continued for over
one year
· Prolonged use of combined hormone replacement therapy (HRT) after
menopause increases risk. But risk returns to that of the general population
within 5 years of stopping HRT.
· Alcohol is a linked to an increased risk of developing breast cancer. Risk
increases with the amount of alcohol consumed. Compared with non-drinkers,
women who consume one alcoholic drink a day have a small increase in risk.
Women who have 2-5 drinks daily have about 1.5 times the risk of women who
do not drink alcohol. Excessive alcohol consumption increases the risk of other
cancers, especially head and neck cancer
· Being overweight or obese after the menopause increases risk. Before
menopause the ovaries produce most of the body’s oestrogen. But after
menopause most of a woman's oestrogen comes from fat.
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7. · Physical activity reduces breast cancer risk. Results of the Women's
Health Initiative shows that 1.5 - 2.5 hours per week of brisk walking reduced a
woman's risk by 18%.
· Long-term heavy smoking is linked to a higher risk of breast cancer,
especially in women who started smoking when they were young. In 2009, the
International Agency for Research on Cancer (IARC) concluded that there is
limited evidence that tobacco smoking causes breast cancer.
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