The recent paper from the UK (Br J of Cancer 2002;87:1234-1245)
is a very well done analysis, and confirms the results we reported
in 2001 (Ellison RC, Zhang Y, McLennan C, Rothman KJ. Exploring
the relation of alcohol consumption to risk of breast cancer.
Am J Epidemiol 2001;154:740-747). In other words, there is probably
a very small increase in the risk of breast cancer associated
with moderate drinking.
The best estimate in our analyses (based on more recent prospective
studies in the US) was that women averaging one typical drink
per day (estimated to contain 12 grams of alcohol) had a risk
ratio by comparison with non drinkers of 1.06; this means the
risk of breast cancer was only 6% higher than that of non-drinkers.
In the recent UK study, it appears that women consuming the equivalent
on one drink (5-14 grams) per day had a risk of 1.01 (in comparison
with a risk of 1.00 for a never drinker) if a "never-smoker,"
1.05 if an "ever-smoker," and 1.03 overall. Thus, they estimate
an overall increase in risk of only 3% from one drink per day
(using the definition of a drink as 5-14 grams/day, which is actually
up to almost two drinks by British standards). While this degree
of increase is beyond the limits of epidemiologic studies to be
very sure about (in that it could still be confounding, and not
truly the cause of the increased risk), it has been found so consistently
by studies around the world that I think that it is true that
there is a very small increase in risk for women who consume even
as little as one drink per day.
It is unfortunate that the authors of the UK paper decided in
the abstract to ignore the fact that one drink per day hadminimal
effect on breast cancer risk and to refer only to the 32% increase
in breast cancer risk for women drinking 35-44 g of alcohol per
day and the 46% increase for women drinking more. This is much
more than anyone recommends, and applies only to a very small
percentage of the population. Further,it has been shown that adequate
intake of thevitamin folate, protects women against any increase
in breast cancer risk from moderate drinking (Zhang S, Hunter
DJ, Hankinson SE, Giovannucci EL, Rosner BA, Colditz GA, Speizer
FE, Willett WC. A prospective study of folate intake and the risk
of breast cancer. JAMA 1999;281:1632-1637).
As I have stated (Ellison RC. Balancing the risks and benefits
of moderate drinking. Ann N Y Acad Sci 2002;957:1-7) - as have
others, women should remember that the protective effects of alcohol
on cardiovascular disease (heart attack and stroke) are very large,
and that cardiovascular disease is associated with ten times the
number of deaths among women as breast cancer, because ofsuch
protection, women who are light-to-moderate drinkers tend to live
longer than non-drinkers.
R. Curtis Ellison, MD Professor of Medicine & Public Health Boston
University School of Medicine 715 Albany Street, Room B-612 Boston,
MA 02118 Tel. (617) 638-8080; Fax. (617) 638-8076