Can Alcohol Really be Directly Linked with Seven Cancers?

A new study has suggested that even small amounts of alcohol consumed on a daily basis can have a significant impact on cancer rates.

The study comes from a review which summarises data from a range of previous studies in order to evaluate evidence regarding alcohol causing cancer.

Researchers found that existing evidence does indeed support a link between alcohol consumption and cancer at seven locations in the human anatomy, including the throat, gullet, liver, colon, rectum and female breast.

The review aimed to summarise data from published biological and epidemiological research, and meta-analyses that have pooled data, to evaluate the strength of evidence that alcohol causes cancer.

Correlations are believed to be strongest for those drinking heavily, but the study also indicated that even low levels of drinking can contribute to a significant proportion of cancer cases.

There is seemingly no safe level of drinking according to the study.

The author concluded that “there is strong evidence that alcohol causes cancer at seven sites, and probably others. The measured associations exhibit gradients of effect that are biologically plausible, and there is some evidence of reversibility of risk in laryngeal, pharyngeal and liver cancers when consumption ceases. The highest risks are associated with the heaviest drinking, but a considerable burden is experienced by drinkers with low to moderate consumption, due to the distribution of drinking in the population.”

However, despite the conclusions of researchers, it is important to be aware that the review did not reveal its methodology.

Conclusions must be considered largely the opinion of the single author behind the review, with more of a correlation than any causality having been proven.

The study was carried out by one researcher from the University of Otago, New Zealand, and was published in the peer-reviewed scientific journal Addiction.

Media coverage of the study has generally been fairly balanced and accurate, although the tone of reporting tended towards the indication that this is a new discovery, when it is in fact based on previous research.

Alcohol has been considered potentially carcinogenic for some time, but utilising observational studies to find links between the substance and cancer is still considered uncertain and somewhat controversial.

An obvious weakness of the study, apart from the lack of methods included, is that the author fails to describe how research was identified, as would occur in a systematic review.

It is also notable that the correlation was comparatively weaker for colorectal, liver and breast cancer.

While the research is certainly interesting, it is far too early to draw broad-based conclusions, and the jury is still very much doubt on the carcinogenic properties of alcohol.

Indeed, the author acknowledges the limitations of these observational findings, stating that “the limitations of cohort studies mean that the true effects may be somewhat weaker or stronger than estimated currently, but are unlikely to be qualitatively different.”


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