From bad teeth to cancer

An investigation reveals a worrying relationship between dental problems and cancer, which goes through tobacco and alcohol.

Teeth and oral prostheses in poor condition increase the risk of cancer in smokers and drinkers. This has been determined by a research conducted from the Faculty of Dentistry of the National University of Córdoba (UNC) in Argentina, which analyzed data collected over a decade. The conclusion fills a gap in the bibliography in this field of health and for this reason the empirical demonstration provided by the team directed from the Department of Stomatology at the Faculty of Dentistry acquires unusual relevance.

Until now it was known that the intake of alcohol and tobacco favored the development of oral cancer, but it had never been proven that chronic mechanical irritation potentiated the action of these factors to such an extent that, in certain cases, the risk doubled.

Chronic mechanical irritation or trauma, caused by poorly placed, maladjusted prostheses or teeth in poor condition – which scrape or hurt the mouth for months or years – is significantly associated with oral cancer. And the risk is higher when the person uses tobacco or alcohol, even in moderate amounts.

That is the finding made by the team headed by Eduardo David Piemonte, from UNC. In addition to the UNC, the German Hospital of Buenos Aires in Argentina, the National Institute for Cancer Studies of Taiwan and the Faculty of Dentistry of King’s College London in the United Kingdom have also collaborated in the team. One of the co-authors of the study, Saman Warnakulasuriya from Sri Lanka, is director of the Department of Oral Cancer at the World Health Organization. The group from the Faculty of Dentistry approached Saman in 2013, during an international congress. At that time, the WHO official was already aware of his work, but disagreed about the results due to the paucity of evidence. Some time later, with the evidence obtained, he decided to join the team.

Oral cancer is among the twenty most frequent worldwide, with squamous cell carcinoma being the most common. The advantage over other oncological pathologies is that this variant can be diagnosed with the naked eye. That is why periodic dental check-ups are so important. In fact, the Faculty of Dentistry offers the possibility of free consultations to any interested person.

For this field of health, the discovery made by Piemonte and his colleagues contributes to the study of the causes of the disease from an original perspective, because it provides empirical evidence on a subject on which there was insufficient scientific bibliography.

Until now, it was known that the intake of alcohol and tobacco favored the development of oral cancer. But chronic mechanical irritation had never been shown to potentiate the action of these factors, thus, in certain cases, the risk is doubled.

For this research, the data was collected between 2009 and 2019. The sample consisted of two groups of 106 cases each: the first, made up of patients with oral cancer, and the second, of healthy people (control group).

In all cases, they were over 18 years old –with an average age of 63 years–, identified as male or female, who were treated at the UNC School of Dentistry, or at the German Hospital Oral Medicine Service. from Buenos Aires.

Tobacco use was reported in 44.3% of cancer patients and in 48.1% of the control group. The alcohol, meanwhile, in 50% of the cases that are in the first group and in 34% of those that are located in the second.

In the group of people diagnosed with cancer, 73.6% showed evidence of chronic mechanical irritation. Ill-fitting dentures and broken teeth that scrape the tongue are the most common traumas. In the control group, meanwhile, only 32.1% presented this condition.

How factors are potentiated

The combination of chronic mechanical irritation and alcohol increases the risk of developing the disease by 53%. “Our study shows that chronic irritation is significantly associated with oral cancer. The data also show that a higher risk is correlated with the interaction not only between tobacco and alcohol, but also between these two factors and oral trauma,” Eduardo Piemonte, director of the study, told Argentina Investiga.

“This means that the factors make synergy. You don’t have to smoke excessively to get oral cancer. Doing it moderately with a bad oral condition already enables that possibility. In contrast, good oral health could reduce the risk of contracting this disease”, says the researcher.

One piece of information that caught the attention of the research team was that chronic irritation also served as a risk factor, even in the absence of tobacco and alcohol. But this does not mean that it is carcinogenic by itself.

“Human beings are exposed to various carcinogenic factors, some of which have not yet been identified. And, within this framework, chronic mechanical irritation could play a role in a multifactorial model, even in the absence of both drugs”, adds Laura Cecilia Werner, from the German Hospital in Buenos Aires and co-author of the study.

“In other countries, trauma or chronic mechanical irritation, which our team exposes as a very important causative agent, is denied. We are one of the few research groups in the world that considers irritation as a factor that can increase the risk of cancer and that has achieved an empirical demonstration of this”, concludes René Panico, head of the Chair of Stomatology at the Faculty of Dentistry.

Research has led to the conclusion that having poor teeth and dentures increases the risk of cancer if you smoke or drink alcohol regularly. (Photo: UNC / Argentina Investiga)

A sum of factors

The research team has different lines of work, all linked to oral cancer. Years ago, they demonstrated the effect of the accumulation of risk factors in the development of oral cancer. “Usually we hear that tobacco and alcohol consumption are causes of oral cancer, but we observed that only half of those we attended in the office met this condition, so we had to reconsider the analysis of the causes”, points out Piemonte.

Carcinogenesis is a multicausal process. This implies that the disease is generally produced by a set of “not sufficient” and “not necessary” causes.

“Not enough” means that any cause needs at least one other factor to trigger a pathology. And “not necessary” implies that the presence of a reason is not always associated with the appearance of a certain disease. “Oral squamous cell carcinoma meets these rules,” says Jerónimo Lazos, a member of the group.

“We observed that only smoking was not enough to develop oral cancer. We then recorded how many factors we detected in each patient and found that rather than an individual reason, it was an accumulation of factors. For example: if a patient smokes, drinks alcohol and is also of advanced age, all this increases the risk ”, she completes.

Another risk factor in certain regions of the center and southeast of the province of Córdoba is the consumption of water contaminated with arsenic, especially that obtained from wells in rural areas, because this contaminant is found in the first water table. “Those who have drunk it for more than ten years are at risk of suffering from any type of cancer, including oral cancer,” says Gerardo Gilligan, another member of the team.

To reach these results, the team carried out a study between 2009 and 2013, which included 53 patients with oral cancer and 100 healthy patients (control cases). The research was approved by the Council for the Ethical Evaluation of Health Research, under the Ministry of Health of the Province of Córdoba.

The factors analyzed were alcohol, tobacco, and arsenic water consumption for more than ten years, chronic oral lesions, HPV infections, family history of cancer, and unbalanced diets with a high percentage of red meat.

A smoker was considered to be someone who smoked occasionally or regularly for more than a year, with an average of one cigarette per day. And a drinker was considered to be someone who drank alcohol regularly for more than a year.

Regarding the number of factors present, the range was from 0 to 7 in the same patient, with an average of 2.72 factors for the total in the population. The group of cancer patients averaged 4.32 cumulative factors, while the average for the control group was 1.87.

The study is titled “Chronic mechanical irritation enhances the effect of tobacco and alcohol on the risk of oral squamous cell carcinoma: a case-control study in Argentina”. And it has been published in the academic journal Clinical Oral Investigations. (Source: Soledad Huespe / UNC / Argentina Investiga)