Alcohol and oral cancer

alcohol and oral cancer
Photo: Andriy Popov –  123RF

With people consuming more alcohol during the pandemic, our drinking habits could be setting us up a for a future spike in oral cancer cases—though there’s good reason to be optimistic about faster and better tools for early diagnosis. Kathy Graham reports

COVID-19 with its lockdowns and restrictions has had an upside: we’re cooking and gardening more. But it also has a downside: we’re drinking more.

According to a recent FARE (Foundation for Alcohol Research and Education) survey, one in seven Australian drinkers are concerned about the amount of alcohol they or someone in their household is drinking, 11 per cent are drinking to cope with stress and 14 per cent are drinking daily.

In addition, consumer spending data indicates we’ve been buying more booze since the beginning of COVID-19 lockdowns, particularly online.

The trend has raised the red flag for a possible future spike in oral cancer. “Strong evidence shows that long-term high levels of alcohol consumption alone increases the risk of oral cancer by about four-fold,” says Michael McCullough, Professor of Oral Medicine at the Melbourne Dental School, adding that four people each day are diagnosed with the disease. Yet the problem is few make this connection, he warns. One reason is that oral cancer has previously been mainly associated with long-term heavy smokers. “It was recognised alcohol was a part of that risk but over the last several decades we’ve noticed there’s less people smoking, but the oral cancer rate appears to be increasing.”

Just how alcohol causes cancer isn’t fully understood but one mechanism may involve oral bacteria. Bacteria metabolise alcohol in the mouth and some do this better than others. 

While there’s no doubt that excessive amounts of alcohol over an extended period increases the likelihood of developing oral cancer, even smaller amounts may be harmful, says Professor McCullough.  Why? Most alcohol is broken down, or metabolised, in your liver cells by the enzyme alcohol dehydrogenase, to a known carcinogen, acetaldehyde.

“Most of this occurs in the liver,” says Professor McCullough, “but about 30 per cent occurs outside the liver, particularly in the mouth a couple of minutes after drinking alcohol. In some people this can occur so rapidly that they have really very, very high levels of acetaldehyde for that first couple of minutes, in their mouth. For them, alcohol could be much more deleterious, and have a greater impact on the mucosa of their mouth than in others.”

Given this, the ability to assess an individual’s potential risk of developing oral cancer related to oral alcohol metabolism could help enormously. Dr McCullough envisages taking a saliva sample before and just after the patient rinses their mouth with alcohol then comparing acetaldehyde levels. His hope is to “put such a tool in the hands of dentists who can talk to their patients about that risk and the possible need to reassess their alcohol consumption”.

Until then, early diagnosis of oral cancer is key to diminish the morbidity and mortality of this horrific disease.

“We know that if we recognise oral cancers earlier, then they’re easier to deal with,” Professor McCullough says. “The five-year survival for oral cancer has been about 50 to 60 per cent, not changing very much over the last 30 years. Fundamentally, it’s due to late recognition and it’s much better if recognised early. 

The five-year survival for oral cancer has been about 50 to 60 per cent, not changing very much over the last 30 years. Fundamentally, it’s due to late recognition and it’s much better if recognised early.

Professor Michael McCullough, Melbourne Dental School

“Irrespective of what level of COVID lockdowns prevail across Australia, anyone should be examined by a dentist if they’re concerned about changes in their mouth that have been persisting.”

Professor McCullough believes that generally oral health professionals are very good at recognising abnormalities. Indeed, a pilot program in community dental agencies and private dental practices across Victoria last year, led by the Dental Health Services Victoria (DHSV), showed oral health professionals were having more conversations with patients about oral cancer risk with more oral mucosal examinations.

A further challenge is the limited tools to detect and monitor potential oral cancers and skin lesions over time, forcing clinicians to remove suspicious lesions by scalpel biopsy and assess pathology, sometimes repeatedly.

Hence another research project at the Melbourne Dental School and DHSV aims to identify patients more likely to develop oral cancer, without invasive biopsies.

The project uses OptiScan’s state-of-the-art confocal laser endomicroscope (CLE). The hand-held microscope uses a laser light and confocal optics to painlessly perform ‘digital biopsies’.

With the microscope, tissue can be viewed in 3D with 1000-times magnification. This could allow clinicians and surgeons to diagnose cancerous tissue in real time, reducing or eliminating the need to have one or more biopsies taken and sent to a laboratory for analysis.

“We’re quite excited about the intra-oral confocal microscope. They’ve developed a state-of-the-art machine and we intend to assess different mouthwashes that make the nuclei glow, fluoresce, because we’re actually looking at the fluorescent changes,” Professor McCullough says.

Alongside trialling the CLE, the project also aims to develop software to comprehensively record an annotated map of the patient’s mouth. This will make it possible to compare a patient’s ‘mouth map’ with subsequent versions, to assess any changes over time.

If information is power, then Professor McCullough is glad to be having this conversation. “The more we can talk about oral cancer, the better.

“If you have people who start developing a habit now, of high levels of alcohol consumption on a daily basis, and that persists over the next five to 10 years, then that becomes a real problem. We’re not going to know that for another five or 10 years, which is why it’s good to be talking about his now.”  

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