alcohol intake in NHS is fairly similar to that of US women.41 Our study population was predominantly White, but the limited available data suggest that the associations between alcohol and breast cancer does not differ by ethnicity.42 The referent group was women who completely abstained from alcohol. Although this may represent a unique group, there was a linear association with increasing alcohol consumption, rather than an immediate jump from the referent group. Finally, PAR's can provide a sense of the potential public health impact of alcohol, but they are dependent upon the distribution of alcohol consumption in the population and also assume causality and this is an observational study. Also, PAR's do not account for the overall disease burden and with an estimated 172,000 new cases of invasive breast cancer in the US, a PAR of 10% would translate to 17,200 cases prevented annually.43
