Tag Archives: cancer

No Confusion: Alcohol Causes Seven Cancers

There is “strong evidence” that alcohol causes seven cancers, and other evidence indicates that it “probably” causes more, according to a new literature review published online July 21 in Addiction.

Epidemiologic evidence supports a causal association of alcohol consumption and cancers of the oropharynx, larynx, esophagus, liver, colon, rectum, and female breast, says Jennie Connor, MB, ChB, MPH, from the Department of Preventive and Social Medicine, University of Otago, in Dunegin, New Zealand.

In short, alcohol causes cancer.

This is not news, says Dr Connor. The International Agency for Research on Cancer (IARC) and other agencies have long identified alcohol consumption as being causally associated with these seven cancers.

So why did Dr Connor, who is an epidemiologist and physician, write a new review? Because she wants to “clarify the strength of the evidence” in an “accessible way.”

There is “confusion” about the statement, “Alcohol causes cancer,” explains Dr Connor.

Public and scientific discussion about alcohol and cancer has muted the truth about causality, she suggests.

“In the public and the media, statements made by the world’s experts are often given the same weight as messages from alcohol companies and their scientists. Overall messages become unclear. For these reasons, the journal [Addiction] has tagged this piece [her review] as ‘For Debate,’ ” she told Medscape Medical News.

The use of causal language in scientific and public discussions is “patchy,” she writes.

For example, articles and newspaper stories often use expressions such as “alcohol-related cancer” and “alcohol-attributable cancer”; they refer to a “link” between alcohol and cancer and to the effect of alcohol on “the risk of cancer.”

These wordings “incorporate an implicit causal association, but are easily interpreted as something less than cancer being caused by drinking,” observes Dr Connor.

“Stop drinking alcohol” is a catch phrase that could be ― but is not ― akin to “stop smoking,” she also suggests.

“Currently, alcohol’s causal role is perceived to be more complex than tobacco’s, and the solution suggested by the smoking analogy — that we should all reduce and eventually give up drinking alcohol — is widely unacceptable,” writes Dr Connor.

The newly published review “reinforces the need for the public to be made aware of the causal link between alcohol and cancer,” said Colin Shevills, from the Alcohol Health Alliance UK, in a press statement.

“Research shows that only around 1 in 10 people [in the UK] are currently aware of the alcohol-cancer link,” he said.

“People have the right to know about the impact of alcohol on their health, including its link with cancer, so that they can make informed choices about how much they drink,” added Shevills.

The lack of clarity about alcohol causing cancer, Dr Connor believes, is related to alcohol industry propaganda as well as the fact that the “epidemiological basis for causal inference is an iterative process that is never completed fully.”

What the Epidemiology Says

Dr Connor writes that the strength of the association of alcohol as a cause of cancer varies by bodily site. The evidence is “particularly strong” for cancer of the mouth, pharynx, and esophagus (relative risk, ~4-7 for ≥50 g/day of alcohol compared with no drinking) but is less so for colorectal cancer and liver and breast cancer (relative risk, ~1.5 for ≥50 g/day).

“For cancers of the mouth, pharynx, larynx and oesophagus there is a well-recognized interaction of alcohol with smoking, resulting a multiplicative effect on risk,” adds Dr Connor.

Other cancers are also likely caused by alcohol. Dr Connor writes that there is “accumulating research” supporting a causal contribution of alcohol to cancer of the pancreas, prostate, and skin (melanoma).

The exact mechanisms as to how alcohol, either alone or in combination with smoking, cause cancer “are not fully understood,” although there is some supporting “biological evidence,” she says.

One British expert had an opinion about alcohol’s carcinogenicity.

In a statement about the new review, Prof Dorothy Bennett, director of the Molecular and Clinical Sciences Research Institute at St. George’s, University of London, said: “Alcohol enters cells very easily, and is then converted into acetaldehyde, which can damage DNA and is a known carcinogen.”

In the new review, Dr Connor describes various hallmarks of causality that have been found in epidemiologic studies of alcohol and these seven cancers, such as a dose-response relationship and the fact that the risk for some of these cancers (esophageal, head and neck, and liver) attenuates when drinking ceases.

Current estimates suggest that alcohol-attributable cancers at the seven cancer sites make up 5.8% of all cancer deaths worldwide, she states.

The alcohol industry has a lot at stake, she says, which in turn leads to “misinformation” that “undermines research findings and contradicts evidence-based public health messages.”

A recent example comes from New Zealand, where a symposium on alcohol and cancer was covered by national media. An opinion piece by an industry-funded scientist in the capital’s daily newspaper disputed the evidence reported from the conference. That essay was entitled: “To Say Moderate Alcohol Use Causes Cancer Is Wrong.”

The essay included the statement: “While chronic abusive alcohol consumption is associated with a plethora of health problems including cancer, attributing cancer to social moderate drinking is simply incorrect and is not supported by the body of scientific literature.”

But there is no safe level of drinking with respect to cancer, says Dr Connor, citing research about low to moderate levels of alcohol, which has been covered by Medscape Medical News.

This was also the conclusion of the 2014 World Cancer Report, issued by the World Health Organization’s IARC.

The promotion of health benefits from drinking at moderate levels is “seen increasingly as disingenuous or irrelevant in comparison to the increase in risk of a range of cancers,” writes Dr Connor.

Public health campaigns “with clear messages” are needed to spread the word about alcohol’s carcinogenicity, she told Medscape Medical News.

“I think that the UK is leading the way. Alcohol consumption as a public health issue has had high exposure in the UK over quite a number of years,” said Dr Connor, who provided links to two awareness campaigns, the Balance campaign, and the Balance Northeast campaign.

Earlier this year, the United Kingdom issued new guidelines on alcohol drinking, recommending that men drink no more than women and warning that any amount of alcohol increases the risk of developing a range of cancers.

Organizations in New Zealand are also taking action. The New Zealand Medical Association, the Cancer Society of New Zealand, and the National Heart Foundation have all adopted evidence-based position statements that “debunk” cardiovascular benefits as a motivation to drink and that highlight cancer risks, Dr Connor said.

Dr Connor has disclosed no relevant financial relationships.

Addiction. Published online July 21, 2016. Full text
Medscape Medical News © 2016 WebMD, LLC
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Cite this article: No Confusion: Alcohol Causes Seven Cancers. Medscape. Jul 27, 2016.

Exercise Cuts the Risk for 13 Cancers

Higher levels of leisure-time physical activity are associated with a significantly lower risk of developing a number of cancers, the results of a pooled analysis of data from more than a million Europeans and Americans reveal.

The findings, published online May 16 in JAMA Internal Medicine, indicate that higher levels of physical activity reduced the risk of developing cancer in 13 of the 26 cancers reviewed.

For that group of 13 cancers, the risk reduction ranged from 10% to 42%.

The affected cancers were esophageal adenocarcinoma (hazard ratio [HR], 0.58), liver cancer (HR, 0.73), lung cancer (HR, 0.74), kidney cancer (HR, 0.77), gastric cardia cancer (HR, 0.78), endometrial cancer (HR, 0.79), myeloid leukemia (HR, 0.80), myeloma (HR, 0.83), colon cancer (HR, 0.84), head and neck cancer (HR, 0.85), rectal cancer (HR, 0.87), bladder cancer (HR, 0.87), and breast cancer (HR, 0.90).

The cancers with risk not positively affected by physical activity included those of the prostate and melanoma.

“These findings support promoting activity as a key component of population-wide cancer prevention and control efforts,” say the researchers.

In an accompanying editorial, Marilie D. Gammon, PhD, Gillings School of Public Health, University of North Carolina at Chapel Hill, described the findings as “exciting,” because they “underscore the importance of leisure-time physical activity as a potential risk-reduction strategy to decrease the cancer burden in the United States and abroad.”

She emphasizes the need for further research into the underlying mechanisms for the association between physical activity and cancer and into the critical timing of exposure to exercise, as well as the types and amounts of activity that have the most impact.

Lead researcher Steven C. Moore, PhD, MPH, National Cancer Institute, Bethesda, Maryland, told Medscape Medical News that three mechanisms have been proposed to relate physical activity to lower cancer risk.

The first, he explained, is via sex hormones. Previous studies have shown, for example, that estrogens occur in lower levels in physically active women. “The second hypothesis is related to insulin, which is that active people have lower levels of insulin, and insulin itself maybe a cancer risk factor,” he said.

The third is connected to inflammation, with studies indicating that exercise is linked to lower levels of inflammatory markers, and that inflammation “is a general cancer risk factor.”

Although it appears from the current findings that the relationship between physical activity and cancer risk is strongest for gastroesophageal and hematologic cancers, it was not possible to determine which of the hypotheses most lends itself to explaining the association.

Dr Moore said: “It’s hard to pin it down exactly, because in the ideal study, you would want to have physical activity as well as those inflammatory factors measured and the cancer outcome, and nobody’s done that study.”

The findings nevertheless strengthen recommendations on minimum activity levels, because the message that exercise reduces cancer risk can be added to that for cardiovascular disease.

Dr Moore noted: “In terms of getting people to be active, it depends on the number of communities and the number of constituencies that are invested in pushing it as a public health message.”

For him, the study “at least in part aligns the evidence for cancer with the evidence for heart disease.”

Dr Moore said: “In other words, there’s enough evidence now to suggest that physical activity may be an important part of cancer prevention and control messages, so that it can be pushed within that research community, and not just within that research community but perhaps also that advocacy community.”

For the analysis, the researchers pooled data from 12 prospective cohorts from Europe and the United States that included self-reported physical activity, yielding a total of 1.44 million individuals (median age, 59 years).

Because different measures of physical activity were used across the studies, the team converted activity to metabolic equivalents (METs), with exercise of moderate intensity defined as 3 or more METs. The median activity level was the equivalent of 150 minutes of moderate-intensity activity per week, or 75 minutes of vigorous intensity, or the equivalent combination.

Higher activity levels of leisure-time physical activity were associated with younger age, more education, lower body mass index (BMI), and lower likelihood of being a current smoker.

During a median follow-up of 11 years, there were 186,932 incident cases of cancer.

The researchers found that higher levels of physical activity were associated with an increased risk for prostate cancer (hazard ratio [HR], 1.05) and malignant melanoma (HR, 1.27). Further analysis showed that the latter was statistically significant only in US regions where there are higher levels of solar ultraviolet radiation (HR, 1.26).

There were suggestions of associations between increased physical activity and reduced risk for gallbladder cancer, small intestine cancer, and non-Hodgkin lymphoma.

It was estimated that physical activity was associated with an overall 7% reduction in the risk of developing cancer (HR, 0.93).

Although BMI reduced the association for several cancers, 10 of the inverse associations remained significant after adjustment. Smoking modified the association only for lung cancer.

Editorialist Dr Gammon told Medscape Medical News that the pooled analysis has strengthened the evidence for an association between physical activity and some of the rarer cancers. “It’s really nice to be able to put it all together, because each of the individual studies were underpowered,” she said.

She believes that the intensity and duration of physical activity needed to lower cancer risk is likely to be tumor specific. “For instance, it was so much easier for us to figure out that physical activity was related to colon cancer, but it was much, much harder to do it with breast, and I’m thinking it’s possible that it could be related to dose and intensity.”

She added: “I think we’re going to need to do more individual type studies to try to really nail that down better, but right now, I would say the best evidence is what the CDC is recommending.”

Dr Gammon concluded that it is “really hopeful” to have the possibility of “such a good strategy to be able to reduce the risk of developing cancers, because some of the cancers on that list are very rare and very deadly.”

The study was supported by the Intramural Research Program of the National Institutes of Health. The work reflected in the editorial was supported in part by grants from the National Institutes of Health. The authorsand editorialists have disclosed no relevant financial relationships.

JAMA Intern Med. Published online May 16, 2016.